Dissertations / Theses on the topic 'Biomarker, latent tuberculosis infection'

Adaptive Immunantworten gegen Mycobacterium tuberculosis (M. tuberculosis) sind von entscheidender Bedeutung für die effektive Eindämmung des Erregers sowie den Schutz vor einer erneuten, sekundären Tuberkulose (TB). Obwohl Schlüsselfaktoren wie die Th1 Zytokine IFN-gamma und TNF-alpha bekannt sind, blieben Bemühungen zur Identifizierung eindeutiger immunologischer Parameter, welche ausschlaggebend für den Krankheitsverlauf sind, bislang erfolglos. Ein besseres Verständnis der zugrunde liegenden Immunprozesse sowie die Identifikation projektiver Biomarker für TB sind zentrale Ziele dieser Arbeit. Zur Bearbeitung dieser Fragestellungen wurden adaptive Immunantworten gegen M. tuberculosis in gesunden Probanden mit LTBI und Patienten mit aktiver TB analysiert. Hierfür wurde die Erkennung unterschiedlicher Proteine des Erregers durch die Messung IFN-gamma exprimierender CD4+ CD45RO+ Gedächtnis T Zellen untersucht. Eine Besonderheit war die Einbeziehung sogenannter Latenz-assoziierter Proteine, welche in Zusammenhang mit Dormanz und Reaktivierung des Bakteriums stehen. 7 Tage in vitro Inkubation in Verbindung mit einer zweimaligen Restimulation belegten eine spezifische Erkennung durch CD4+ CD45RO+ T Zellen für die Mehrheit der getesteten Proteine bei Spendern mit LTBI. Der darauf folgende Vergleich zwischen Patienten mit aktiver TB und Personen mit LTBI zeigte signifikant höhere T Zell Antworten für 7 der 35 M. tuberculosis Proteine während LTBI. Bemerkenswerterweise konnten spezifische T Zellen für eines der Protein, nämlich Rv3407, ausschließlich während LTBI gemessen werden und nicht bei Patienten mit aktiver TB. Diskriminanz Analysen zeigten, dass eine Unterscheidung zwischen LTBI und TB Patienten basierend auf T Zell Antwort gegen ausgewählte Latenz-assoziierte Antigene mit einer Genauigkeit von 82% möglich ist. Erneut erwies sich Rv3407 als der mit Abstand bedeutendste Faktor innerhalb der ausgewählten M. tuberculosis Proteine.<br>Adaptive immune responses to Mycobacterium tuberculosis (M. tuberculosis) are crucial for an efficient containment of the pathogen and protection against secondary tuberculosis (TB). Although key mediators like the Th1 cytokines IFN-gamma and TNF-alpha released by M. tuberculosis-specific T cells are known, the immunological correlates determining the outcome of infection remain elusive. A better understanding of the underlying immune processes and the identification of protective biomarkers for TB are central aims of this thesis. To address these topics adaptive immune responses to M. tuberculosis were analyzed in healthy LTBI and patients with active pulmonary TB. The recognition of M. tuberculosis derived antigens was studied by measuring the expression of IFN-gamma in CD4+ CD45RO+ memory T cells. A special hallmark was the inclusion of latency proteins associated with dormancy, reactivation and resuscitation of the pathogen. Seven days in vitro incubation of PBMC and two rounds of restimulation followed by FACS analysis revealed T cell mediated recognition of the majority of tested latency-associated proteins in donors with LTBI. Comparison between active TB and LTBI documented significantly higher T-cell responses against 7 of 35 tested M. tuberculosis latency-associated antigens in LTBI. Notably, T cells specific for one M. tuberculosis antigen, namely Rv3407, were exclusively detected in the subgroup of LTBI. Discrimination analysis revealed that the T-cell response against selected antigens with our novel assay is capable of distinguishing TB patients and LTBI with 82% accuracy using cross-validation. Again Rv3407 was by far the most influential component present in this cluster. Peptide pool stimulation in a similar fashion identified single distinct candidate epitopes within Rv3407 in four LTBI.

In 2013 Burma, the country of origin for many refugees of whom have resettled in the U.S. was in the top three countries for notification of suspected Latent Tuberculosis Infection (LTBI). Approximately 5%-10% of individuals diagnosed with LTBI are at risk of developing active tuberculosis (TB) disease; the highest risk occurs within two years following the diagnosis. Burmese refugees face a high potential of developing LTBI during resettlement in the U.S. and are at high risk for subsequent TB. Currently, we have limited knowledge of the Burmese Chin refugees' explanatory model (EM) of LTBI. Understanding the EM of these refugees is important because one's EM facilitates the recognition and response to illness, including early diagnosis and treatment. In the context of LTBI, this relates to the potential prevention of active TB disease. The purpose of this ethnographic study was to discover the Burmese Chin refugees' EM of LTBI and to describe the barriers experienced in receiving LTBI treatment. Kleinman's EM provided a conceptual framework to guide this study. A Burmese refugee gatekeeper assisted with community immersion and participant recruitment. Purposive and snowball sampling were used to recruit participants. Data were collected through participant observation and semi-structured interviews. Three data analysis strategies for ethnography that were used included domain, taxonomic, and componential analyses. Domain analysis began after open, inductive coding of the data. Data saturation was reached and the research questions were answered with eight participants. Data from 15 key informant interviews were abstracted into three domains: EM of LTBI, Fear and Stigmatization, and Barriers to Receiving LTBI Treatment. The over-arching theme, LTBI: My Shadowbox was derived from these three domains, 11 categories, and 25 subcategories through iterative and inductive data analysis. The analysis revealed the participants' language, behavior patterns, beliefs, values and health seeking experiences of LTBI in the U.S. The findings from this study will help to inform culturally tailored interventions to reduce LTBI and TB health disparities among Burmese Chin refugees and potentially other Burmese refugee subgroups in the U.S. Knowledge of the Burmese Chin refugees' EM of LTBI can inform health policy for reducing LTBI treatment barriers.

The decision to give preventive treatment to a person with latent tuberculosis infection (LTBI) is a complex one in which morbidity and mortality from potential progression to active tuberculosis (TB) is weighed against the morbidity and mortality associated with potential adverse effects of treatment. Without objective evidence and careful, model-based evaluation of the evidence, it is likely the risks and benefits of the two alternative strategies (treatment or no treatment) will be inaccurately assessed. It is therefore apparent that medical practitioners need assistance when making decisions about treatment of LTBI. A number of decision analyses in the past that are summarised in a systematic review in this thesis have attempted to address this issue. However, the review identified the need for a more individualised decision analysis tool. Further, the systematic review highlighted the importance of using robust estimates of key variables in any decision analysis model on LTBI treatment and it showed that the inclusion of health-related quality of life adjustments has the potential to change the decision for or against treatment of LTBI. Thus, a systematic review of quality of life in TB-related health states was conducted. A new clinical decision aid is presented that has the potential to improve physicians’ capacity to make better and more consistent decisions on treatment for LTBI by taking patients’ individual clinical characteristics into account. It showed that treatment is beneficial in the majority of scenarios for patients with evidence of LTBI. Other aspects of preventive TB treatment that were examined in this thesis include the completion rate of treatment of LTBI, the risk of developing TB among contacts of patients with TB and the prevalence of LTBI and treatment of LTBI among this group.

<p> Approximately one-third of the world's population is infected with the bacteria that cause Tuberculosis (TB) and nearly nine million people around the world become sick with TB disease annually. A total of 10,521 TB cases were reported in the United States in 2011 with foreign-born and racial/ethnic minorities disproportionately affected. Treating Latent Tuberculosis infection (LTBI) is imperative in decreasing the incidence of TB disease as well as preventing strains of TB that are more difficult to treat. Past research studies have reported conflicting results regarding barriers to LTBI preventive therapy, success of shorter therapies, and how to best encourage compliance with LTBI preventive therapy. This study was guided by the Health Belief Model (HBM) using a comparative descriptive design to examine characteristics of subjects started on LTBI preventive therapy in 2010 and 2011 in a county in which adherence rates dropped from 76.9% in 2010 to 45.4% in 2011. The subjects included all persons identified with LTBI according to North Carolina TB Program guidelines that initiated preventive therapy in the years of 2010 and 2011, with a total of 13 subjects in 2010 and 11 in 2011. A record review was performed to gather information for analysis. Hispanic ethnicity was moderately associated with not completing LTBI preventive therapy. Significant differences between the study groups were reason for not completing therapy and risk factors for progression to TB disease, but neither was significantly associated with preventive therapy completion.</p>

The current, most widely used method to screen for latent tuberculosis infection is the Mantoux tuberculin skin test, where tuberculin is injected into a patient's arm and may result in a cutaneous induration forming at the site of injection. A diameter measurement of the resultant induration, recorded using a ruler and ball point pen, is currently used to indicate the presence of latent tuberculosis infection. Limitations associated with the tuberculin skin test procedure are the crudeness of the induration measurement method, the follow-up clinical visit required from patients to have their induration measured, and the need for trained clinicians who can perform the induration measurement. These limitations motivated research into a mobile phone-based screening system which can be used to obtain a more accurate measurement of the induration without the need for a second visit to the clinic by patients. The prototype screening tool consists of a user interface for capturing induration images and a backend processing system that produces a threedimensional reconstruction of the induration for measurement. Recommendations from previous studies on the prototype screening tool, which involved evaluation of the mobile application using mock induration images, included improving the accuracy of measuring the induration and evaluating the tool on real induration images. The aim of this study was to evaluate the existing backend system and explore an alternative assessment approach for assessing the induration. This was achieved through the following objectives: (1) applying the current backend system to real induration images, (2) examining the need for three-dimensional reconstruction for delineation of the induration for measurement and (3) exploring an alternative method for the assessment of induration images using deep learning. Results for the first objective showed the three-dimensional reconstruction to be unsuccessful on real images. This was due to the homogeneity between the indurations and the surrounding skin, rendering the algorithm ineffective in delineating the indurations to obtain the diameter measurement required for diagnosis. The second objective involved determining whether the image orientation or induration height affected the diagnostic measurement. It was found that real indurations are much flatter and more subtle compared to the mock indurations used in the previous studies. This motivated an alternative image assessment approach using deep learning. However, deep learning approaches require large databases of annotated images to prevent overfitting on training data. The last objective therefore involved the design and implementation of a generative adversarial network for generation of synthetic images from a limited number of real images, which allowed the generation of an unlimited number of realistic-looking synthetic images from 150 real induration images.

More than 10 million people in the United States are known to have latent tuberculosis infection (LTBI), and more than 300,000 begin treatment for LTBI annually. However, many fail to adhere to therapy for numerous reasons. The purpose of this project was to evaluate the impact of a new guideline, Targeted Tuberculin Testing and the Treatment of Latent Tuberculosis, at inner-city tuberculosis (TB) control clinic in the United States. The practice-focused question for the project asked if the implementation of the clinical guideline using a shorter regimen improved LTBI treatment adherence. The health beliefs model was the framework used to guide the project. I analyzed data from deidentified LTBI treatment adherence records of 12 patients before the change to the shorter treatment regimens and 12 patient records 1 year after the change. Results after implementation of the new treatment guideline showed no improvement in adherence. Before the guideline implementation, 75% (n=9) of individuals had adhered to traditional therapy whereas, after the shortened course was implemented, only 66.7% (n=8) of the random sample adhered to treatment. It is important to evaluate new methods of treatment and determine success early to promote health and reduce complications of ineffective treatment of TB. These results can support positive social change by raising awareness of the need to evaluate new treatment effectiveness early. Such knowledge can help providers and clinicians examine the barriers to adherence to the medications used for treating TB and implement appropriate measures to overcome the obstacles.

Introduction: Despite management advances worldwide, tuberculosis still remains a serious uncontrolled disease. The absence of either a ‘gold’ standard diagnostic test, or a conventional rapid ‘reference’ laboratory test for asymptomatic Mycobacterium tuberculosis (MTB) carriers complicates disease control. Through mandatory screening of high-risk groups, early diagnosis of latent tuberculosis infection (LTBI) cases allows recognition and better control of the tuberculosis pandemic. Materials and Methods: The current tuberculosis screening guidelines as recommended by the World Health Organization, chest X-ray and tuberculin skin test were assessed and revealed rises in TB morbidity and fatality trends in the Kuwait population (low incidence country). In order to evaluate options for LTBI diagnosis, the current work implemented a 4-month prospective, observational, repeated-measure and randomly implemented survey on 180 new immigrants to Kuwait using a structured risk factor questionnaire whilst, simultaneously evaluating the performance of the two standard diagnostics (chest X-ray and tuberculin skin test) with the new biomarker interferon gamma release assays (T-SPOT .TB test and QuantiFERON Gold In-Tube test (QNF-GIT)); which detect the release of interferon gamma (INF-γ) released from sensitization to specific MTB antigens. Results: Associations between various epidemiological risk factors - such as socio-demographic status, smoking and environmental exposure-contact - were associated in the laboratory diagnosed LTBI participants. Positive identification of LTBI prevalence detected by two radiologists was 10.1% having ‘moderate’ inter-reader agreement (Kappa = 0.505), compared to no positives being detected by three pulmonologists. TST results were negative (less than 10-mm ‘cut-off’) even in the 86.1% Bacillus Calmette-Guérin vaccinated expatriates. Estimated LTBI using QNFGIT was 28.3% compared to 41.1% positive T-SPOT .TB test. Both interferon gamma assays revealed concordant ‘abnormal’ results in 26.1% with ‘good’ agreement (kappa = 0.627). Conclusion: Detection of latent tuberculosis infection can be facilitated by introducing evidence-based diagnostic classification depending on history taking of epidemiological-related risk factors and chest X-ray plus either interferon gamma assays.

Background: Migrant farmworkers are among the highest-risk populations for latent TB infection (LTBI) in the United States with numerous barriers to healthcare access and increased vulnerability to infectious diseases. LTBI is usually diagnosed on the border using the tuberculin skin test (TST). QuantiFERON-TB Gold In-Tube (QFT-GIT) also measures immune response against specific Mycobacterium tuberculosis antigens. The objective of this study is to assess the comparability of TST and QFT-GIT to detect LTBI among migrant farmworkers on the border, as well as to examine the effects of various demographic and clinical factors on test positivity. Methods: Participants were recruited using mobile clinics on the San Luis US-Mexico border and tested with QFT-GIT and TST. Demographic profiles and clinical histories were collected. Kappa coefficients assessed agreement between TST and QFT-GIT using various assay cutoffs. Logistic regression examined factors associated with positive TST or QFT-GIT results. Results: Of 109 participants, 59 of 108 (55 %) were either TST (24/71, 34 %) or QFT-GIT (52/106, 50 %) positive. Concordance between TST and QFT-GIT was fair (71 % agreement,kappa= 0.38, 95 % CI: 0.15, 0.61). Factors associated with LTBI positivity included smoking (OR = 1.26, 95 % CI-1.01-1.58) and diabetes/high blood sugar (OR = 0.70, 95 % CI = 0.51-0.98). Discussion: Test concordance between the two tests was fair, with numerous discordant results observed. Greater proportion of positives detected using QFT-GIT may help avoid LTBI under-diagnosis. Assessment of LTBI status on the border provides evidence whether QFT-GIT should replace the TST in routine practice, as well as identifies risk factors for LTBI among migrant populations.

Preventative interventions often demand that resources be consumed in the present in exchange for future benefits. Understanding these trade-offs, in a context of resource constraints, is essential for policy makers. Cost-effectiveness analysis is one tool to inform decision-making. Targeted testing and treatment (TTT) for latent tuberculosis infection (LTBI) consists in identifying people at high risk for LTBI for preventive treatment to decrease the risk that they will develop active tuberculosis disease (ATBD). The state of Tennessee began conducting TTT statewide in 2001. This study uses a decision tree to evaluate the cost and outcomes of TTT for LTBI in Tennessee, compared to passive ATBD case finding (PACF). Key event probabilities were obtained from the Tennessee TTT program and from the literature. Outcomes are measured in terms of Quality Adjusted Life Years (QALY). The cost-effectiveness threshold was set at $100,000/QALY saved. One-way sensitivity analyses around factors related to study design (exclusion of patient costs, secondary transmission, discount rate and analytical horizon), the program’s environment (prevalence of LTBI and drug resistance, ATBD treatment costs) and program performance (program maturity, treatment initiation and completion rate, testing in low-risk group, test characteristics, screening costs) were conducted, as was probabilistic sensitivity analysis (PSA) which takes into account the uncertainty in multiple parameters simultaneously. The base case, with a 25-year time horizon and 3% discount rate, shows that TTT prevents 47 ATBD cases, and saves 31 QALYs per 100,000 patients screened for LTBI at a societal cost of $12,579 (2011 US$) per QALY saved. Sensitivity analyses identified value thresholds that would trigger a change in preferred policy. PSA shows that the likelihood that TTT would be cost-effective is low. Decision makers interested in implementing TTT should carefully assess the characteristics of the local TB epidemic and expected program performance to determine whether TTT is preferable over PACF from a cost-effectiveness viewpoint.

BACKGROUND Latent tuberculosis infection (LTBI) management is a crucial component of tuberculosis prevention in high-risk individuals. A global approach including diagnosis and treatment completion ensures good outcomes.T-cell-based interferon-gamma release assays (IGRAs) were first developed a decade ago, at which time they represented a promising alternative to the tuberculin skin test (TST); however, they too are limited by their poor ability to predict future active TB, being only slightly better than TST at best. Since the implementation of IGRAs, several cross-sectional studies showed the comparison of TST and IGRAs results in populations at risk for developing active tuberculosis, with still not enough evidence based on longitudinal cohorts and properly designed clinical trials to date. HYPOTHESIS 1. In immunosuppressed individuals: The addition of an IGRA test might benefit the diagnostic strategy in order to maximize TST sensitivity. 2. In recently infected individuals (contact tracing studies): Implementing the use of IGRAs could narrow the proportion of preventive therapy in individuals at risk of developing active tuberculosis, without increasing its risk. OBJETIVES 1. Immunosuppressed individuals: 1.1 To assess whether a comprehensive latent tuberculosis screening and treatment program includind an IGRA can prevent anti-TNF–associated tuberculosis.
 1.2. To assess the usefulness of QFT-GIT in predicting the development of active tuberculosis in comparison to the TST in patients undergoing liver transplant and hematopoietic stem cell transplant. 2. Contact tracing studies 2.1 To ascertain whether using IGRA, either in place of TST or to confirm a positive TST, might reduce the number of people considered for preventive treatment, without leading to a significant increase in the risk of subsequent active tuberculosis.
 2.2 To determine whether the use of QFT-GIT as a confirmatory test of the TST to target preventive therapy in tuberculosis contacts might reduce the number of individuals receiving treatment without an increased risk of subsequent active tuberculosis, as compared to a TST-based strategy. METHODS The clinical studies included in this thesis comprise three longitudinal cohort studies, a systematic review and a clinical trial. The three observational studies are retrospective analyses of prospectively gathered data, recorded as part of the clinical assistance in the Tuberculosis Unit at Bellvitge University Hospital. The research ethics committee approved them all. The statistical analyses were made with the SPSS (Statistical Package for the Social Sciences) software (version 17 and 22). The level of significance was fixed at α = 5%, and confidence intervals (CIs) for differences in proportions were estimated using OpenEpi software version 2.3.1.122. RESULTS 1. Immunosuppressed individuals: 1.1 First, although anti-TNF–associated tuberculosis can be greatly reduced, a certain risk remains during the first year of treatment. Second, the 2-step TST approach for LTBI screening prior to anti-TNF therapy is no longer justified. Third, systematic periodic retesting for LTBI in patients with negative test results prior to anti-TNF therapy is not required. 1.2 The rate of post-transplant TB among QFT- GT-positive patients was both low and comparable to that of the TST in this cohort of liver transplant and Hematopoietic Stem Cell Transplant recipients. 2. Contact tracing studies In low-incidence settings of TB, using QFT-GIT to confirm positive TST reactors allows a significant reduction of TB infection diagnoses and preventive therapy prescriptions without increasing the risk of active disease.<br>ANTECEDENTES: Desde la implementación de los IGRAs (Interferon Gamma Release Assays) se ha generado poca evidencia científica fundamentada en ensayos clínicos o en el seguimiento longitudinal de cohortes. HIPÓTESIS: 1. La implementación de los IGRAs en el cribado de infección tuberculosa latente (ITL) en pacientes inmunodeprimidos puede mejorar la rentabilidad diagnóstica. 2. Los IGRAs pueden optimizar la selección de pacientes candidatos a recibir tratamiento de ITL en el estudio de contactos (EC), reduciendo su número, sin aumentar el riesgo de tuberculosis activa (TB). OBJETIVOS: 1. Demostrar la eficacia de un protocolo sistemático de prevención de TB que incluye un IGRA en los candidatos a anti-TNF. 2. Calcular los valores predictivos (VP) para el desarrollo de TB de la prueba de la tuberculina (PT) y un IGRA en pacientes candidatos a trasplante hepático (TH) o de progenitores hematopoyéticos (PH). 3. Demostrar que basar la indicación del tratamiento para ITL en el resultado de un IGRA disminuye la proporción de candidatos a tratamiento en comparación con PT, sin que por ello aumente el riesgo de TB. MÉTODOS: La tesis responde a los objetivos mediante un ensayo clínico multicéntrico y tres estudios prospectivos aprobados por el Comité de Ética del Hospital de Bellvitge, así como una revisión sistemática. RESULTADOS: 1. En candidatos a agentes anti-TNF se ha demostrado la eficacia del protocolo sistemático para la prevención de TB. El cese de PT en dos tiempos ha supuesto una disminución significativa en la proporción de diagnósticos y tratamientos de ITL sin aumentar del riesgo de TB ulterior. No es necesario repetir el cribado sistemáticamente tras un resultado negativo inicial. 2. En los candidatos a TH y de PH, el VP positivo para el desarrollo de TB del IGRA ha sido comparable a PT, siendo bajo, y por tanto no útil para predecir el desarrollo de TB. El VP negativo ha sido elevado en ambas pruebas. 3. La estrategia diagnóstica que confirma con un IGRA los resultados positivos de la PT ha demostrado ser no inferior a la estrategia basada únicamente en PT para la prevención de tuberculosis en el EC, permitiendo reducir significativamente el número de candidatos a tratamiento preventivo.

Background: The incidence of tuberculosis (TB) among Inuit is over 400 times that of Canadian-born non-indigenous people. To address this, more patients will need to complete preventative treatment. Methods: First, data were extracted retrospectively for all patients with a tuberculin skin test (TST) implanted in Iqaluit, Nunavut between January 2012 and March 2016 and used to identify sources of loss from the latent TB infection (LTBI) cascade of care. Associations between demographic and clinical factors and treatment non-initiation and treatment non-completion were identified using regression models. Second, using a slightly expanded version of the retrospective dataset plus other sources, a Markov model was utilized to assess the cost-effectiveness of a novel shortened regimen for LTBI (12 weeks of once weekly isoniazid and rifapentine (3HP)) compared to the current standard of care (9 months of isoniazid monotherapy (9H)). Results: Treatment non-initiation and non-completion were the largest sources of loss of TST positive patients from the cascade of care. LTBI testing via employment screening was associated with treatment non-initiation while older age was associated with both treatment noninitiation and non-completion. In cost-effectiveness analysis, 3HP was dominant over 9H: costs were lower ($835 vs $1229 per person) and health outcomes slightly improved (20.14 vs 20.13 QALYs gained per person treated), largely due to an improved treatment completion with 3HP. Conclusions: Interventions to increase LTBI treatment initiation and completion in Iqaluit are needed. This could include the use of 3HP instead of 9H for LTBI treatment which may improve treatment completion and result in cost savings and slightly improved health outcomes.

Latent tuberculosis infection (LTBI), a product of exposure to Mycobacterium tuberculosis (Mtb), can lead to tuberculosis (TB) and further cause death if untreated. Fortunately, TB can be prevented with LTBI treatment. Targeting newly arrived visa holders for LTBI screening and treatment is an effective strategy for decreasing future TB burden. However, LTBI treatment completion rates are low, and researches had primarily focused on the nonrural U.S. setting. This study, using a retrospective cohort design under the epidemiological disease triangle framework evaluated (a) the treatment completion rates for 2 cohorts of visa holders (i.e., immigrants, N = 31 and refugees, N = 109) with LTBI residing in the rural setting using Pearson's chi-square analysis, (b) mean times on LTBI treatment using Kaplan-Meier survival analysis, and (c) predictors of time on treatment using Cox proportional hazard regression. Study findings revealed immigrants had higher treatment noncompletion rates over refugees (25.6% and 19.3%). The potential risk factors for noncompletion were being older than 24 years of age (HR = 0.18, p = 0.01). There were also significant interactions for the time on treatment between (a) being < 25 years old and visa type (HR = 0.23, p = 0.04), (b) being < 25 years and traveling longer (miles) to treatment facility (HR = 0.25, p = 0.03), or (c) being < 25 years and Mtb blood-test positive (HR = 0.35, p = 0.05). These findings suggest interventions targeting visa holders older than 24 years may increase the rate of treatment completion and decrease the future TB cases. Therefore, the study promotes social change by providing actionable, rural-population-specific information for the prioritization of visa holders at increased risk of experiencing LTBI treatment noncompletion.

Latent tuberculosis infection (LTBI) is a global health issue that affects approximately one quarter of the world’s population. It refers to a state of persistent immune response to Mycobacterium tuberculosis without clinical evidence of active tuberculosis (TB). Latent tuberculosis infected individuals are asymptomatic and not contagious to others, however 5-15% of all infected individuals are at risk of developing active tuberculosis and become contagious, severely ill, or worse, die from active TB. There are identified risk groups that are targeted for identification, diagnosis and treatment of latent tuberculosis infection. These are human immunodeficiency virus (HIV) patients, children and adolescents, household or close contacts of active TB cases, migrants, refugees, prisoners and health care workers. The standard treatment used for treating LTBI is the isoniazid monotherapy. It has a high proven efficacy rate but is linked to poor acceptance and low completion rates, basically due to its long treatment duration and poor tolerability. A newer treatment regimen is the rifapentine plus isoniazid combination therapy. It is an effective regimen against LTBI and has a shorter treatment duration. The aim of this literature study was to evaluate the efficacy of rifapentine plus isoniazid combination therapy compared with the isoniazid monotherapy as treatment of latent tuberculosis infection. This thesis was based on five randomized clinical trials collected from PubMed database. The studies should have entailed an efficacy comparison between isoniazid monotherapy and rifapentine plus isoniazid combination therapy for the treatment of patients with latent tuberculosis. The studies showed lower rates of active TB and death in the rifapentine plus isoniazid combination group in comparison with the isoniazid monotherapy. The studies also proved that rifapentine plus isoniazid combination therapy was noninferior to the standard isoniazid monotherapy. The completion rates were significantly higher in the combination therapy arm. The safety profile between the two treatment regimens was similar, but with an increased hepatotoxicity rates in the isoniazid-only arm. The rifapentine plus isoniazid combination therapy is as efficacious as the isoniazid monotherapy. This shorter regimen could be used as first hand therapy as well for latent tuberculosis patients with high-risk of developing active TB as it has shown good tolerability and higher completion rates that is important to successfully treat LTBI and help eliminate TB worldwide.<br>Latent tuberkulos är ett globalt hälsoproblem som drabbar ungefär en fjärdedel av världens befolkning. Den definieras som ett tillstånd av immunreaktion mot Mycobacterium tuberculosis utan kliniska tecken på aktiv tuberkulos (TB). De infekterade individerna är asymtomatiska och inte smittsamma för andra, men 5–15% av alla infekterade individer riskerar att utveckla aktiv tuberkulos och bli smittsamma, bli allvarligt sjuka, eller värre, dö av aktiv tuberkulos. Personer med latent tuberkulos som tillhör riskgrupperna prioriteras för identifiering, diagnos och behandling av latent tuberkulos. Dessa riskgrupper är humant immunbristvirus (HIV)-patienter, barn och ungdomar, nära kontakter till personer med aktiva TB-fall, migranter, flyktingar, fångar och vårdpersonal. Standardbehandlingen mot latent tuberkulos är isoniazid monoterapi. Den har en högt beprövad effektivitetsgrad men är kopplad till dålig acceptans och låga kompletteringsgrader, på grund av framförallt den långa behandlingstiden och dålig tolerans. En nyare form av behandling är rifapentin kombinerat med isoniazid. Den är en effektiv behandling mot latent tuberkulos med en kortare behandlingstid. Syftet med denna litteraturstudie var att utvärdera effekten av kombinationsterapi med rifapentin och isoniazid jämfört med isoniazid monoterapi för behandling av latent tuberkulos. Detta examensarbete baserades på fem randomiserade kliniska prövningar hämtade från PubMed-databasen. Samtliga fem studier innefattade effektivitetsjämförelse mellan isoniazid monoterapi och kombinationsterapi med rifapentin och isoniazid vid behandling av patienter med latent tuberkulos. Alla fem studier undersöktes visade lägre frekvens av aktiv TB och dödlighet i kombinationsterapi med rifapentin och isoniazid jämfört med isoniazid monoterapi. Resultatet bevisade också icke-underlägsenhet för kombinationsterapin jämfört med isoniazid monoterapin. Kompletteringsgraden var signifikant högre i kombinationsterapin. Säkerhetsprofilen mellan de två terapin var likartad, men med en ökad hepatotoxicitet i isoniazid monoterapi gruppen. Kombinationsterapi med rifapentin och isoniazid är lika effektiv som isoniazid monoterapi. Denna kortare behandling kan också användas som förstahandsbehandling för latent tuberkulos patienter med hög risk att utveckla till aktiv tuberkulos eftersom den har visat god tolerabilitet och högre kompletteringsgrad som är viktigt för att framgångsrikt behandla latent tuberkulos och hjälpa till att eliminera TB över hela världen.

A manutenção da infecção latente pelo M. tuberculosis (TBIL) pode ser atribuída à sua capacidade de sobreviver durante anos no organismo humano em um estado não replicativo (dormente). A proteína HspX do M. tuberculosis, induzida sob condições de hipóxia, está fortemente associada com a manutenção da viabilidade do bacilo na TBIL. O presente estudo tem como objetivo, verificar se a superexpressão da proteína HspX altera a expressão de genes envolvidos com a síntese de componentes da parede celular, replicação do DNA e divisão celular de bacilos, assim como, na expressão de genes envolvidos com a resposta imune inata em macrófagos infectados com esses bacilos. O gene hspX foi amplificado pela PCR a partir do DNA do M. tuberculosis H37Rv, clonado no vetor de expressão pFPCA1GFP, e a proteína HspX expressa em M. smegmatis mc2155. As bactérias, nas quais, a presença da proteína recombinante foi confirmada por Western Blot, foram utilizadas, para a análise de expressão gênica tanto em bactérias quanto em macrófagos infectados. O estudo de expressão gênica foi realizado utilizando a RT-qPCR. Quando comparado aos controles, as bactérias que expressavam a proteína HspX apresentaram uma redução na expressão de genes de replicação do DNA e divisão celular, que foi acompanhado por uma tendência a filamentação das células e uma redução no tamanho das colônias. Além disso, nos macrófagos infectados com a bactéria expressando a proteína HspX, houve um aumento tanto da expressão do mRNA quanto da secreção de IL-1b, citocina importante para estabilização do granuloma, e uma redução na expressão de IRGM, gene relacionado com o processo autofágico, importante mecanismo de defesa do hospedeiro contra bactérias intracelulares. Portanto, em conjunto, essas alterações de expressão gênica, em consequência da presença da proteína HspX sugerem uma contribuição, direta ou indireta, dessa proteína para a adaptação morfológica e metabólica da bactéria dormente durante a TBIL, e consequentemente, para a resposta imune inata dos macrófagos infectados favorecendo a viabilidade intracelular dessas bactérias.<br>The maintenance of Mycobacterium tuberculosis infection latent (TBIL) may be attributed to its ability to persist for years in the host in a non-replicative state (dormant). The HspX protein from M. tuberculosis, induced under hypoxic, is strongly associated with maintaining the bacillus viability in TBIL. This study aims to determine if HspX overexpression chances the expression of genes involved in the synthesis of cell wall components, DNA replication and cell division of bacilli, as well as, the expression of genes involved in innate immune response of macrophages infected. The gene hspX was amplified by PCR from DNA of M. tuberculosis H37Rv, and cloned into the expression vector pFPCA1GFP. The HspX was expressed in M. smegmatis mc2155 and the recombinant protein was confirmed by Western blot. The bacterias expressing HspX were used for gene expression analysis both in bacteria and in infected macrophages by RT-PCRq. In bacterias expressing HspX, it was observed a reduction in expression of genes involved in DNA replication and cell division, and with cells more filamentous and smaller colonies, compared with controls. In addition, in macrophages infected with bacillus expressing HspX, there was an increase in both mRNA expression and secretion of IL-1b, an important cytokine for granuloma stability, and a reduction in expression of IRGM, an autophagic gene, important for host defense mechanism against intracellular bacteria. Together, these results suggest a direct or indirect contribution of HspX protein for metabolic and morphological adaptation of dormant bacteria in TBIL, and for the innate immune response in infected macrophages, improving the bacteria intracellular viability.

Thesis (MScMed)--Stellenbosch University, 2008.<br>ENGLISH ABSTRACT: Setting This study was conducted in the Tygerberg area of Cape Town in South Africa. Background A third of the world’s population is latently infected with Mycobacterium tuberculosis, and correlates of protection against progression to active disease urgently need to be identified to facilitate the development of an effective vaccine against the disease. The production of IFN-γ is recognised as an immune correlate of protection from tuberculosis, but other immune regulators have been implicated in playing a significant role in protective immunity. The aims of this project were three-fold: (i) to identify promising TB vaccine candidates by screening a panel of novel MTB antigens, by stimulating whole blood cultures in vitro with the novel proteins and quantifying the level of IFN-γ production, (ii) to identify other cytokines and chemokines that may be immune correlates of protection using the Luminex fluorescent bead-based technique and (iii) to compare the performance of the two techniques. Methods Antigen Screening study Whole blood of 57 adult and adolescent participants defined as latently infected individuals was stimulated with a panel of 78 novel TB-specific, DosR- or RD1-encoded antigens. The 7-day culture supernatants were used in IFN-γ ELISA to quantify the level of IFN-γ production. Luminex Assay study Whole blood culture supernatants of 15 HIV negative, TST positive adults were used in the Luminex LINCO 21-plex cytokine assay. This was done to determine which of 21 cytokines, that may be LTBI-associated cytokines, were produced after stimulation with 9 TB-specific recombinant antigens, and to quantify their level of expression. Results In the antigen screening study, it was found the majority of the 78 proteins tested were able to induce a positive IFN-γ response. The classic TB antigens were used as controls, and the frequency of responses was highest after stimulation with ESAT-6 and TesatCFP10 (80 – 85% of responders). Ten latency antigens elicited an IFN-γ response in 19 – 45% of participants, and five reactivation antigens stimulated a positive reaction in 15 – 48% of responders. The category of antigens that elicited the most frequent and highest responses overall was the resuscitation-promoting factors (Rpf). Over 30% of participants responded to all 5 Rpfs, and the level of responses were equally divided in the low and moderate-to-high levels, with an additional 5% of responses in the high (>1000pg/ml) range. In the Luminex study, the positive stimulant TesatCFP10 consistently induced expression of most cytokines. In addition latency antigens Rv1733c, Rv0569 and Rv2029c also induced moderate-to-high level cytokine expression. A Th1-biased cytokine profile was observed, with the preferential expression of pro-inflammatory and cell-mediated cytokines like IFN-γ, TNF-α, IP-10, MIP1-α and G-CSF being produced. Th2 cytokines IL-4, IL-5, IL-13 and eotaxin were very poorly expressed or were not expressed at detectable levels. A very strong induction of IL-6, IL-8 and MCP-1 was observed, but this cytokine/chemokine association suggested contamination of the recombinant antigens with bacterial endotoxins. Conclusion In this study of latently infected individuals, the pattern of response observed for both assays is largely a Th1-biased expression profile. The whole blood ELISA method is a well-established assay for quantifying IFN-γ in culture supernatants, and has proven to be effective here. This study has demonstrated, in humans with LTBI, immune recognition of these novel MTB-specific antigens as illustrated by the positive IFN-γ levels induced after stimulation. The multiplex technology is also a very versatile and sensitive assay, capable of detecting multiple analytes simultaneously in one sample. The multiplex has been valuable here in identifying some antigens as potential vaccine candidates, and a subset of cytokines as potential immune mediators and prognostic indicators in TB infection.<br>AFRIKAANSE OPSOMMING: Studie-area Hierdie studie was gedoen in die Tygerberg area van Kaapstad in Suid-Afrika. Agtergrond ‘n Derde van die wêreld se bevolking is latent geïnfekteer met Mycobacterium tuberculosis en korrelate van beskerming teen die siekte moet geïdentifiseer word om die ontwikkeling van ‘n effektiewe enstof te fasiliteer. Die produksie van IFN-γ is welbekend as ‘n immuunkorrelaat van beskerming teen tuberkulose (TB), maar ander immuunreguleerders speel ook ‘n belangrike rol in beskermende immuniteit. Die doelwitte van hierdie projek was drievoudig: (i) om belowende TB-entstof kandidate te identifiseer deur die sifting van ‘n paneel van nuwe MTB antigene mbv die in vitro stimulasie van volbloed kulture, ii) om ander sitokiene en chemokiene as immuunkorrelate van beskerming te identifiseer deur van die Luminex fluorescent bead-based tegniek gebruik te maak, en (iii) om die twee tegnieke te vergelyk op grond van hul prestasie as prognostiese of siftings metodes in latente infeksie. Metodes Antigeen siftings studie Volbloed van 57 volwasse en adolessente deelnemers, geïdentifiseer as latent geïnfekteerde individue, was gestimuleer met ‘n paneel van 78 nuwe TB-spesifieke DosR- or R-gekodeerde antigene. Die 7-dae kultuur supernatante was gebruik in ‘n IFN-γ ELISA om die hoeveelheid IFN-γ produksie the kwantifiseer. Luminex assay studie Volbloed kultuur supernatante van 15 HIV negatiewe, TST positiewe volwassenes was gebruik in die Luminex LINCO 21-plex cytokine assay. Dit was gedoen om die tipes en hoeveelheid ander LTBI-geassosieerde sitokienes te identifiseer wat geproduseer word na stimulasie met 9 TB-spesifieke rekombinante antigene. Resultate In die antigeen siftings studie is gevind dat die meerderheid van die 78 getoetste proteïene ‘n positiewe IFN-γ reaksie kon induseer. Vir die kontroles was die frekwensie van reaksies die hoogste na stimulasie met ESAT-6 en TesatCFP-10 (80 – 85% van reageerders). Tien latensie antigene was gereeld herken deur 19 – 45% van deelnemers en vyf reaktiverings-antigene het ‘n positiewe reaksie in 15 – 48% van reageerders gestimuleer. Die kategorie van antigene wat die meeste en hoogste response veroorsaak het, was die resusitasie-promoterende faktors (Rpf). Meer as 30% van deelnemers het op al 5 Rpfs gereageer en die vlak van reaksies was gelyk verdeel in die lae en matig-tot-hoog vlakke, met ‘n addisionele 5% van reaksies in die hoë (>1000pg/ml) reeks. In die Luminex studie het die positiewe stimulant TesatCFP-10 konsekwent die positiewe uitdrukking van die meeste sitokiene geïnduseer. Saam met dit het die latente antigene Rv1733c, Rv0569 en Rv2029c ook matige-toe-hoë vlakke van sitokien uitdrukking geïnduseer. ‘n Th1-gebaseerde sitokien profiel was waargeneem, met die begunstigde uitdrukking van pro-inflammatoriese en sel-gemedieerde sitokiene soos IFN-γ, TNF-α, IP-10, MIP1-α en G-CSF. Th2 sitokiene IL-4, IL-5, IL- 13 en eotaksien was of baie sleg uitgedruk of onder naspeurbare vlakke uitgedruk. ‘n Baie sterk induksie van IL-6, IL-8 en MCP-1 was waargeneem, maar hierdie sitokiene/chemokiene assosiasie stel moontlik kontaminasie van die rekombinante antigene met bakteriële endotoksiene voor. Samevatting Die reaksiepatroon wat in hierdie studie tussen die twee toetse waargeneem is, was grootliks ‘n Th1-gebaseerde uitdrukkingsprofiel vir latente infeksie met TB. Die volbloed ELISA metode is a betroubare gevestigde toets vir die kwantifisering van IFN-γ in kultuur supernatante, wat ook in hierdie studie bewys is om effektief te wees. Hierdie studie het gedemonstreer dat die nuwe TB-spesifieke antigene effektief positiewe IFN-γ response in mense met LTBI induseer. Die multipleks tegnologie is ook ‘n baie veelsydige en sensitiewe toets, wat in staat is om veelvoudige analite gelyktydig in een monster te kan opspoor. In hierdie studie was dit veral waardevol in die identifisering van ander moontlike antigene as prognostiese kandidate en sitokiene as immuunbemiddelaars in TB-infeksie.

Despite the progress that has been made with global control programmes, tuberculosis (TB) remains a significant challenge to health. Better diagnostics, shorter and more effective treatment regimens and improved vaccines are urgently needed. There is also increasing awareness of the need to tackle the huge burden of latent TB infection, which is estimated to affect one-third of the global population. Targeted preventative therapy is the pragmatic solution to this problem. Unfortunately, current diagnostics lack the necessary resolution to accurately identify individuals at risk of progressing to active TB disease. It has recently been proposed that TB exists on a continuous spectrum, which likely represents the dynamic interaction between the host and pathogen. Delineating this spectrum may identify individuals at risk of disease reactivation who would benefit from targeted treatment. The work presented in this thesis describes the novel use of an ex vivo whole blood functional assay to measure the capacity of individuals with active TB disease and latent infection to control mycobacterial growth. The assay identified differential functional responses that discriminated between conventional diagnostic groups, but also showed considerable overlap. Enhanced mycobacterial growth control occurred in patients with active TB disease, which may reflect a general state of immune activation. The wide range of responses seen among latently infected patients is consistent with the concept of a spectrum of infection. Characterisation of different control profiles was undertaken using a multi-platform approach. Differential gene expression was dominated by type I interferon and inflammatory signatures seen in active TB patients and some individuals with latent TB. Clustering analysis showed clear associations with functional responses. Cytokine and chemokine studies revealed strong correlations with mycobacterial growth control. Finally, increases in inflammatory monocytes, polyfunctional T cells, activated and atypical memory B cells and IgG1 responses all demonstrated correlations or associations with functional responses. These findings have potential application in developing a biosignature for TB reactivation and predictive models of risk that warrant further investigation.

Tuberculosis (TB) remains one of the world’s leading causes of mortality due to a single infectious agent, with approximately 1.5 million deaths and 9.2 million new cases per year as estimated in 2006. It is assumed that about 5-10% of individuals infected with M. tuberculosis develop TB and the remaining 90-95% contain M. tuberculosis through their immune systems, but have a latent tuberculosis infection (LTBI). To effectively control TB, it is essential to detect individuals with LTBI and to reliably diagnose active TB. Conventional TB diagnosis continues to rely on smear microscopy and culture that have several known limitations in terms of both speed and sensitivity that delay the diagnosis and, consequently, hold-up TB treatment and increase the spread of infection in the community. M. tuberculosis infection remains widespread, but the disease is generally limited to the primary infection stage. Patients with an immune defect or impaired immunity are more prone to develop the disease. In LTBI, the host immune response is capable of controlling the infection by the release of chemokines and cytokines produced by T helper (Th) cells, critical for the outcome of the infection. Several cells of the immune system are involved in the control of TB, from the macrophages and dendritic cells, called antigen presenting cells (APC) to the T cells, CD4, CD8, gamma delta T cells. Activation of these cells with excessive pro inflammatory responses can lead to tissue damage, with the need of mechanisms to counteract this, such as Th2 and T regulatory cells (Treg)-mediated responses. The optimal scenario would therefore seem to have balanced Th1, Th2 and Treg response, suited to the immune challenge. The balance between these types of response is reflected in the resultant host resistance against infection. Therefore the aims of the thesis were to find new approaches for diagnosis of active TB (First Part) and LTBI (Second Part). In this work we wanted to explore the immune mechanisms of TB pathogenesis with particular focus on the impact of Treg on suppressing M. tuberculosis-specific response (Third Part). For the diagnosis of active TB, we describe an alternative PCR methodology based on the amplification of small DNA fragments, originated from cells dying throughout the body (transrenal DNA; Tr-DNA) and detected in urine. It was found that small M. tuberculosis DNA fragments were specifically detected in the cell-free fraction of urine specimens from pulmonary TB patients. To detect LTBI, we compared the performances of two short-incubation interferon (IFN)-g release assays (IGRAs), the commercial QuantiFERON TB-Gold and the in-house whole blood stimulation with region of difference (RD)-1 proteins, with those of a 7-day whole blood stimulation and tuberculin skin test (TST). In an effort to find new markers for LTBI diagnosis, we also evaluated the production of pro-inflammatory cytokines [interleukin (IL)-1, IL-2, IL-6 and Tumor Necrosis Factor (TNF)-alfa], anti-inflammatory cytokines (IL-4, IL-10, IL-13) and chemokines [inducible protein (IP)-10, Macrophage Inflammatory Protein (MIP)-alfa, MIP-1beta, IL-8] after specific stimulation. The results raise the hypothesis that short-incubation IGRAs mainly detect recent or ongoing infection with M. tuberculosis, while prolonged-incubation IGRAs seem to be more sensitive for the diagnosis of past latent infection. Moreover we found that IL-2 and IP-10 may be additional markers for TB infection after RD1 specific stimulation. Finally we wanted to evaluate the impact of Treg on suppressing M. tuberculosis-specific response. Using classical markers for Treg recognition, discordant results were found in terms of Treg expansion during active TB disease. Recently CD39 has been shown to be an accurate marker for Treg detection. Objectives of this part of the thesis were: 1) to identify Treg expressing CD39 in patients with TB and to compare the results with those obtained by the standard phenotypic markers; 2) to evaluate if Treg are expanded in vitro by exogenous IL-2 or by antigen-specific stimulation; 3) to characterize Treg function on the modulation of antigen-specific responses. In this study we demonstrated that CD39 is a useful marker to detect Treg because within CD4+CD25high cells, it identifies a cell subset characterized by high production of transforming growth factor (TGF)-beta1 and the absence of IFN-gamma expression. Moreover, we showed that CD39+ Treg are expanded by M. tuberculosis-specific stimulation in patients with active TB disease.

Tuberculosis (TB) remains the main cause of death in people living with HIV (PLHIV). Indeed, PLHIV have a 20-30% greater risk of developing TB compared to HIV-uninfected subjects and have lower TB treatment success rates. In 2014, among the 9.6 million incident cases of TB reported worldwide, 12% occurred in PLHIV and 0.4 million deaths from HIV-associated TB were recorded.Mycobacterium tuberculosis is the main etiological agent for TB. For a majority of individuals, the immune response upon infection by M. tuberculosis is sufficient to prevent the development of disease, but insufficient to clear the bacteria. This leads to the persistence of viable M. tuberculosis in diverse cells with no resulting clinical manifestations, an entity known as latent tuberculosis infection (LTBI). The resulting reservoir of M. tuberculosis is vast, and an estimated one third of the world population is concerned. For subjects with LTBI, the life-time risk of reactivation and progression to TB lies between 5 and 10%. However, if co-infected with HIV, the risk is much greater and reaches 10% per year. According to a Cochrane review in 2010, the screening and treatment of LTBI in PLHIV reduces this risk by 30-60%. This prevention strategy is therefore widely recommended. However, the implementation of LTBI screening and treatment into standard HIV-care has been limited. In this work, three different approaches have been used to understand and address this issue, focusing on a low TB-incidence and high-income setting.The first approach was to assess the implementation of LTBI screening in HIV-care across Belgium and identify its barriers as perceived by the caregivers on the field. Raising awareness to this issue was an indirect objective of the study. A multi-choice questionnaire was sent to 55 physicians working in a Belgian AIDS reference center or satellite clinic. A response rate of 62% was obtained. Only 20% of participants performed LTBI screening on all their patients and notable variations in the screening methods used were observed. A large majority of participants were in favor of targeting LTBI screening to HIV-infected patients at highest risk of TB rather than a systematic screening of all PLHIV. These results have been communicated to the Belgian LTBI working group, currently updating the national LTBI screening guidelines. Indeed, targeting screening to those at highest risk of TB is an attractive strategy in low-TB incidence countries and is already recommended in the United Kingdom. However, to date, no score assessing the risk of TB in PLHIV has been validated. Among the barriers to LTBI screening identified by the participants of this first study, the most frequently reported were lack of sensitivity of screening tools, risk associated to polypharmacy and toxicity of treatment. Improving the sensitivity of LTBI screening was the cornerstone of the second approach. The available screening tools for LTBI are the tuberculin skin test (TST) and two Interferon-gamma release assays (IGRAs): the QuantiFERON-TB Gold-IT (QFT-GIT) and the T-SPOT.TB®. All three lack sensitivity in PLHIV. Various strategies to discover superior LTBI screening tools are therefore being explored, including the development of IGRAs in response to alternative M. tuberculosis antigens to those used in the QFT-GIT or T-SPOT.TB®. A potential candidate is the native Heparin-Binding Haemagglutin (nHBHA), a methylated M. tuberculosis protein regarded as a latency-associated antigen. An in-house IGRA based on nHBHA (nHBHA-IGRA) has been shown to be a promising LTBI screening tool both in immunocompetent adults and in hemodialysed patients. The contribution of this nHBHA-IGRA to the detection of M. tuberculosis in PLHIV was therefore investigated. Treatment-naïve HIV-infected subjects were recruited from 4 Brussels-based hospitals. Subjects underwent screening for latent TB using the nHBHA-IGRA in parallel to the classical method consisting of medical history, chest X-ray, TST and QFT-GIT. Prospective clinical and biological follow-up ensued, with repeated testing with nHBHA-IGRA. Among 48 candidates enrolled for screening, 9 were diagnosed with LTBI by combining the TST and QFT-GIT results (3 TST+/QFT-GIT+, 1 TST+/QFT-GIT- and 5 TST-/QFT-GIT+). All 3 TST+/QFT-GIT+ patients, the TST+/QFT-GIT- patient as well an additional 3 subjects screened positive with the nHBHA-IGRA. These 3 additional patients had known M. tuberculosis exposure risks compatible with LTBI. During follow-up (median 14 months) no case of TB was reported and nHBHA-IGRA results remained globally constant. Multiplex analysis confirmed IFN- as the best read-out for the assay. From this study, we concluded that the nHBHA-IGRA appears complementary to the QFT-GIT for the screening of LTBI in PLHIV and the combination of the two tests may increase the sensitivity of screening. A large-scale study is however necessary to determine whether combining nHBHA-IGRA and QFT-GIT offers sufficient sensitivity to dismiss TST, as suggested by our results. In the same study, a group of HIV-infected adults with clinical suspicion of active TB were also recruited and tested with nHBHA-IGRA. Contrary to results in HIV-uninfected subjects, the nHBHA-IGRA could not discriminate between LTBI and active TB in PLHIV. This is an important caveat as HIV-infected subjects may present subclinical TB.A different angle was used for the third approach to the problem of LTBI in PLHIV. Systemic immune activation (SIA) is one of the principal driving forces in the natural course of HIV-infection. Despite long-term viral suppression by combination antiretroviral treatment (cART), a low-level SIA persists and is associated with an early-onset of age-associated disorders such as cardiovascular disease, dementia and osteoporosis. Causes of SIA in PLHIV are multiple and certain chronic infections appear to be implicated. A recent study in South Africa found that LTBI in PLHIV was associated with an increase in circulating activated CD8+ T-cells. If LTBI should contribute to the persistence of SIA, its screening and treatment could have an additional benefit on the clinical outcome of PLHIV. To investigate this theory, the expression of T-cell activation markers (CD38 and HLADR) as well as the level of plasmatic markers of immune activation (IL-6, sCD14, D-Dimers) were compared between subjects presenting active TB, subjects with LTBI and M. tuberculosis-free persons, with and without HIV-infection. In accordance with previous studies, active TB was associated with higher levels of SIA biomarkers in both HIV-infected and -uninfected groups. Among the HIV-uninfected subjects, no significant difference in biomarker level was found between those presenting LTBI and those with no evidence of M. tuberculosis. The effect of LTBI on activation biomarkers in the HIV-infected groups remained inconclusive because of the small number of individuals in the HIV+/LTBI group. Further investigation is therefore warranted. Interestingly, it was found that plasmatic markers may have a greater sensitivity for the detection of M. tuberculosis-associated SIA than the T-cell activation markers, an important result for future studies.Overall, LTBI in PLHIV is a challenging topic, in particular because of the lack of a gold-standard for the diagnosis of LTBI. Despite suboptimal tools, the evident clinical impact of LTBI screening and treatment in PLHIV on TB incidence justifies its implementation in standard HIV-care. In low TB-incidence countries, who, when and how to screen for LTBI in PLHIV remains unclear. This work offers an overview on the subject with particular focus on possible measures for improvement in the field.<br>Doctorat en Sciences médicales (Médecine)<br>info:eu-repo/semantics/nonPublished

Introduktion: Tuberkulos är en av världens mest spridda infektionssjukdomar. En tredjedel av jordens befolkning beräknas bära på bakterien utan att vara sjuka (latent tuberkulos, LTBI). Närmare tio procent av bärarna utvecklar aktiv tuberkulos någon gång under livet. Europa har jämförelsevis låg incidens av tuberkulos och i Sverige har antalet tuberkulosfall minskat sedan mitten av 40-talet. I Sverige ses de senaste årens ökade antal migranter som en förklaring till en tillfälligt ökad prevalens av tuberkulos. Tidig diagnostik och behandling av tuberkulos är avgörande faktorer för att förhindra smittspridning och ger den enskilde individen möjlighet att hantera sin hälsa, vilket är angeläget ur ett folkhälsoperspektiv. Landstingen/regionerna har valt olika strategier för vilka som ska inkluderas i screening för tuberkulos vid hälsoundersökningar av migranter. Syfte: Syftet med studien var att undersöka prevalens och uppföljning av latent tuberkulos bland migranter som genomgått hälsoundersökning vid vårdcentraler i Region Jönköpings län. Metod: Studien var en retrospektiv observationsstudie utifrån kvantitativ ansats. Data samlades in genom journalgranskning och 361 journaler inkluderades i analyserna. Förekomst av latent och aktiv tuberkulos korrelerades med kön, ålder och ursprungsland. Resultat: Resultaten från studien visade att prevalensen av LTBI i studiepopulationen var 9.4 %. Resultaten visade att LTBI var vanligare hos män och individer &gt; 35 år. Däremot sågs inga skillnader utifrån ursprungsland. Slutsats: Studien är av begränsad storlek och därmed generaliserbarhet. LTBI är relativt vanligt bland migranter. Ytterligare studier behövs för att identifiera optimala rutiner för screening och förebyggande insatser i migrantgruppen.<br>Introduction: Tuberculosis is one of the world's most widespread infectious diseases. One third of the world’s population is expected to carry the bacterium without being ill (latent tuberculosis, LTBI). Nearly ten percent of the carriers develop active tuberculosis sometime during their lifetime. Europe has a comparatively low incidence of tuberculosis and in Sweden the number of cases of tuberculosis has decreased since the mid-40s. In Sweden, the increased number of immigrants in recent years is seen as an explanation for a temporarily increased prevalence of tuberculosis. Early diagnosis and treatment of tuberculosis are key factors in preventing the spread of infection and giving the individual the opportunity to manage their health, which is important from a public health perspective. The county councils/regions have chosen different strategies for whom to be included in screening for tuberculosis in health surveys of immigrants. Aim: The aim of the study was to investigate the prevalence and follow-up of latent tuberculosis among immigrants who have undergone a health examination at health centers in the County of Jönköping. Method: The study was a retrospective observation study based on quantitative approach. Data was collected through journal review and 361 records were included in the analysis. The presence of latent and active tuberculosis was correlated with gender, age and country of origin. Results: The results of the study showed that the prevalence of LTBI in the study population was 9.4%. The results showed that LTBI was more common in men and individuals &gt; 35 years. However, no differences were seen by country of origin. Conclusion: The study is of limited size and thus generalisability. LTBI is relatively common among immigrants. Further studies are needed to identify optimal routines for screening and preventive measures in the immigrant group.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior<br>A interleucina-6 (IL-6) à uma importante citocina que exerce papel fundamental na imunopatogÃnese de diversas doenÃas infecciosas. O objetivo deste estudo foi investigar o nÃvel de produÃÃo sistÃmica de IL-6 e aferir o papel funcional do polimorfismo -174 G>C do gene dessa citocina em indivÃduos diagnosticados como portadores de infecÃÃo latente pelo Mycobacterium tuberculosis (ILTB). Para controle, foram utilizados dois grupos de comparaÃÃo: um deles composto por portadores de tuberculose pulmonar ativa (TB) e o outro formado por indivÃduos saudÃveis, doadores de sangue. O grupo ILTB foi composto por 15 indivÃduos, selecionados dentre os contactantes de portadores de TB pulmonar ativa, atendidos no Hospital SÃo Josà de DoenÃas Infecciosas e no Centro de SaÃde da FamÃlia AnastÃcio MagalhÃes. O grupo TB foi formado por 38 pacientes com TB pulmonar ativa, procedentes do Hospital de Messejana, Hospital de Maracanaà e Hospital Geral Dr. CÃsar Cals. O grupo de indivÃduos saudÃveis contava com 63 doadores voluntÃrios de sangue do Centro de Hematologia e Hemoterapia do CearÃ. A dosagem sÃrica de IL-6 foi realizada por meio de um ensaio imunoenzimÃtico (ELISA), com kit especÃfico fornecido pela Invitrogen Corporation. Para purificaÃÃo do DNA, foi utilizado o kit GFX Genomic Blood DNA Purification, da GE Healthcare. O polimorfismo -174G&#61614;C do gene da IL â 6 foi tipificado pela tÃcnica de reaÃÃo em cadeia da polimerase (PCR), utilizando-se iniciadores de sequÃncia especÃfica (PCR-SSP) (One-Lambda). As medianas de concentraÃÃes sÃricas de IL-6 para os grupos ILTB, TB e saudÃveis foram de, respectivamente, 1,7 pg/mL, 4,3 pg/mL e 0,5 pg/mL (p < 0,0001). Nos trÃs grupos estudados, o genÃtipo encontrado com maior frequÃncia foi o G/G [ILTB = (80%); TB = (58,9%); saudÃveis = (62,8%)]. Em conclusÃo, podemos inferir que a IL-6 deve desempenhar um papel importante na manutenÃÃo do estado de latÃncia, haja vista que sua concentraÃÃo, nos indivÃduos com ILTB, foi 3,4 vezes maior que no grupo saudÃvel. Ademais, constatamos que, na populaÃÃo estudada, o polimorfismo -174G&#61614;C nÃo se mostrou funcional no Ãmbito da infecÃÃo latente pelo Mycobacterium tuberculosis.<br>Interleukin-6 (IL-6) is an important cytokine involved in the pathogenesis of multiple infectious diseases. The aim of this study was to investigate the levels of IL-6 production and to correlate to the -174G>C polymorphism at the IL-6 gene in latent infection with M. tuberculosis (ILTB). As controls, two groups were used. One of them with active pulmonary tuberculosis (TB) patients and the other with healthy blood donors. ILTB group was composed by 15 individuals, selected among active pulmonary TB contacts seen at the Hospital SÃo Josà de DoenÃas Infecciosas and the Centro de SaÃde da FamÃlia AnastÃcio MagalhÃes. TB group had 38 patients with active pulmonary disease seen at the Hospital de Messejana, Hospital de Maracanaà and the Hospital Geral Dr. CÃsar Cals. The third group was composed by 63 healthy blood donors from the Centro de Hematologia e Hemoterapia do CearÃ. Serum levels of IL-6 were measured by an ELISA using specific kits from Invitrogen Corporation. For DNA purification a GFX Genomic Blood DNA Purification kit (GE Healthcare) was used. The -174G&#61614;C polymorphism was analyzed by a SSP-PCR method using One-Lambda kits. Median values of serum levels of IL-6 from ILTB, TB and healthy groups were, respectively, 1.7 pg/mL, 4.3 pg/mL and 0.5 pg/mL (p < 0.0001). For the three studied group, the most frequent genotype found was the G/G (ILTB = 80%; TB = 58.9%; saudÃveis = 62.8%). In conclusion, it is possible to consider that IL-6 should play an important role in the maintenance of latent infection state as its concentrations were 3.4 fold higher in ILTB group than that of healthy controls. Moreover, the -174G&#61614;C polymorpism was not functional in the ILTB group.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-06-29T12:16:23Z No. of bitstreams: 2 Dissertação - Daniel Batista Gomes - 2016.pdf: 3477482 bytes, checksum: 39d73011b1245110ab18fca9b832b249 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)<br>Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-07-10T14:14:40Z (GMT) No. of bitstreams: 2 Dissertação - Daniel Batista Gomes - 2016.pdf: 3477482 bytes, checksum: 39d73011b1245110ab18fca9b832b249 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)<br>Made available in DSpace on 2017-07-10T14:14:40Z (GMT). No. of bitstreams: 2 Dissertação - Daniel Batista Gomes - 2016.pdf: 3477482 bytes, checksum: 39d73011b1245110ab18fca9b832b249 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-12-20<br>Tuberculosis is still a major global health problem. One of the strategies recommended for the control of tuberculosis is the identification and early treatment of individuals with latent M. tuberculosis infection (ILTB). In Brazil, ILTB is not part of the compulsory notification aggravations, but there is a recommendation for States to create instruments for notification and follow-up of cases. In Goiás, a notification form for ILTB was developed in 2012 by the State Department of Health. The objective of the research is to analyze the epidemiological profile of ILTB cases and to characterize the surveillance processes related to the diagnosis and treatment of this disease in this state. The reports of ILTB cases treated between 2013 and 2015 were analyzed. A database linking was carried out considering the cases of tuberculosis reported in the SINAN NET Notification System and the ILTB records. To evaluate the technical and structure aspects of ILTB control services, a structured questionnaire was applied to the supervisors of health surveillance in the 18 health regions of the State. A descriptive and exploratory data analysis was carried out using software SPSS 13.0 and TABWIN 1.6 EPI INFO. 345 cases of ILTB were reported in the study period. The patients' ages ranged from 0 to 92 years (median age 38 years); 65.2% were adults and 10.1% were up to 10 years. Five municipalities (Goiânia, Aparecida de Goiânia, Jataí, Anápolis and Formosa) reported 77.7% of the cases. In 24.6% of the cases, the criterion for treatment of ILTB was the result of Tuberculin Test (TT)> 10mm. In this group all cases were asymptomatic and 78.8% had contact with active tuberculosis. It was identified that 39 cases were HIV positive, corresponding to 12.7% of indications for ILTB treatment. According to health surveillance supervisors, all 246 municipalities had a Tuberculosis Control Program. Concerning the specific training on ILTB, 74 municipalities (30.1%) received this training, reaching 141 health professionals. In relation to the specific training for the application of TT, only three (16.7%) health regions were trained, of which two managed to decentralize this training to some of their jurisdictions. Eleven regional health (61.1%) reported that the number of TT provided by the State Department of Health was inadequate to meet the demands of municipalities. According to supervisors, 88.2% of the municipalities in Goiás do not have the tools to monitor cases of co-infection with HIV. The present study contributed to the knowledge of the epidemiological profile of the reported cases of ILTB, as well as to the process of control of this aggravation in the State. Failures were identified in the ILTB control process in the different regions of the State of Goiás. This study is expected to support effective actions to control tuberculosis in the State.<br>A tuberculose ainda é um grande problema de saúde global. Uma das estratégias preconizada para controle da tuberculose consiste na identificação e tratamento precoce dos indivíduos com infecção latente pelo M. tuberculosis (ILTB). No Brasil, a ILTB não faz parte dos agravos de notificação compulsória, porém existe recomendação para que os Estados criem instrumentos para notificação e acompanhamento dos casos. Em Goiás, uma ficha de notificação para ILTB foi desenvolvida em 2012 pela Secretaria de Estadual da Saúde. O objetivo da pesquisa consiste em analisar o perfil epidemiológico dos casos de ILTB e caracterizar os processos de vigilância relacionados ao diagnóstico e tratamento dessa doença neste estado. Foram analisadas as notificações de casos de ILTB tratados entre 2013 e 2015. Foi realizada a vinculação de base de dados considerando os casos de tuberculose notificados no Sistema de Informação de Agravos de Notificação (SINAN NET) e os registros de ILTB. Para avaliar aspectos técnicos e de estrutura de serviços de controle de ILTB foi aplicado questionário estruturado para os supervisores de vigilância em saúde das 18 regiões de saúde do Estado. Foi realizada análise descritiva e exploratória de dados por meio dos softwares SPSS 13.0 e TABWIN 1.6 EPI INFO. 345 casos de ILTB foram notificados, no período de estudo. A idade dos pacientes variou de 0 a 92 anos (mediana de 38 anos); 65,2% eram adultos e 10,1% tinham até 10 anos. 05 municípios (Goiânia, Aparecida de Goiânia, Jataí, Anápolis e Formosa) notificaram 77,7% dos casos. Em 24,6% dos casos, o critério para tratamento da ILTB foi o resultado do Teste Tuberculínico (TT) >10mm. Nesse grupo todos os casos eram assintomáticos e 78,8% tinham contato com caso de tuberculose ativa. Identificou-se que 39 casos eram HIV positivos, correspondendo a 12,7% das indicações para tratamento ILTB. De acordo com os supervisores de vigilância em saúde, todos os 246 municípios contavam com Programa de Controle da Tuberculose. 74 municípios (30,1%), receberam treinamento sobre ILTB, alcançando 141 profissionais de saúde. Em relação ao treinamento especifico para aplicação do TT apenas 03 (16,7%) regiões de saúde foram capacitadas, das quais duas conseguiram descentralizar esta capacitação para alguns de seus municípios jurisdicionados. 11 regionais de saúde (61,1%) informaram que o número de TT disponibilizado pela Secretaria de Estado da Saúde foi inadequado para atender as demandas dos municípios. Ainda segundo os supervisores, 88,2% dos municípios goianos não dispõem de ferramentas para acompanhamento dos casos de co-infecção com HIV. O presente estudo contribuiu para o conhecimento do perfil epidemiológico dos casos notificados de ILTB, bem como para o processo de controle desse agravo no Estado. Foram identificadas falhas no processo de controle da ILTB, nas diferentes regiões de Saúde do Estado de Goiás. Espera-se que esse estudo possa subsidiar ações efetivas para o controle da tuberculose no Estado.

Made available in DSpace on 2016-12-23T13:56:13Z (GMT). No. of bitstreams: 1 Sandra Mary Jardim Gomes.pdf: 3616033 bytes, checksum: 466661a021314cea1a4f3a38493b1fd1 (MD5) Previous issue date: 2012-06-29<br>Para o controle da Tuberculose (TB) uma das medidas utilizadas no Brasil é o tratamento da infecção latente pelo Mycobacterium tuberculosis (ILTB), que é feita nos Programas de Controle de TB (PCT). A evolução da infecção para a doença durante a vida é estimada em 5-10% em relação a um adulto imunocompetente, porém, na criança estima-se 43%. Esta pesquisa foi um estudo observacional, analítico, que objetivou analisar o perfil epidemiológico e os fatores relacionados ao abandono do tratamento da ILTB. Foram analisados os indivíduos até 15 anos de idade que estavam em tratamento para ILTB, nos PCT dos municípios prioritários, ou seja, os mais populosos da Grande Vitória: Vitória, Vila Velha, Serra e Cariacica, nos locais que utilizam a ficha de notificação do tratamento da ILTB. A ficha foi utilizada como instrumento de coleta dos dados. O período pesquisado foi de julho de 2009 a agosto de 2010. Foram encontrados 144 indivíduos em tratamento para ILTB, sendo 140 (97,22%), a indicação foi de serem contatos de TB, 46 (31,94%) abandonaram o tratamento, e 98 (68,06%) concluíram o tratamento. A maioria dos indivíduos era contato de TB, e quando foi analisada a situação da baciloscopia (BAAR) do caso índice do contato, a maioria tanto do grupo que abandonou, quanto do grupo que concluiu o tratamento, 97,62% e 87,91% (p=0,06), respectivamente, eram positivos. Quanto ao tipo de contato, o domiciliar foi o mais frequente, e também entre os dois grupos, tanto os que abandonaram quanto os que concluíram, totalizaram 81,82% e 84,21% (p=0,72), respectivamente, seguidos de outros, que foram os tios, avós, que moravam próximos. As crianças e adolescentes avaliados tinham na sua maioria cicatriz da vacina BCG (Bacilo de Calmette e Guérin) presentes, e tinha na sua maioria o Rx de tórax normal. Analisou-se também se indivíduos adolescentes (&#8805;10 anos), apresentaram mais chance de abandonar o tratamento da ILTB, em relação às crianças com menos de 10 anos de idade, pois as mesmas necessitam ajuda dos seus cuidadores para uso da medicação, porém, a maioria de ambos os grupos, concluíram o tratamento, adolescentes 75% e crianças 64,13% (p=0,17). Este estudo reforça a necessidade do controle dos contatos dos doentes da TB, identificando prioritariamente as crianças e adolescentes e desenvolvendo estratégias para a adesão ao tratamento da ILTB. O estudo também pode estimular a melhoria do sistema de notificação dos casos de tratamento da ILTB, já que, apesar da orientação do MS, a sua implantação ainda não foi padronizada<br>Controling of Tuberculosis (TB) one of the measures used in Brazil is the treatment of latent infection by Mycobacterium tuberculosis (ILTB), which is made in the TB Control Program (PCT). The evolution of the infection to disease during the life is estimated at 5-10% related to immunocompetent adult, however, in child is estimated 43%.This research was an observational and analytical study, which aimed to analyze the epidemiological profile and factors related to renunciation of treatment for ILTB. Individuals were analyzed until 15 years old who were undergoing treatment for ILTB, in the PCT of the priority municipalities of Vitória, Vila Velha, Serra and Cariacica, which are the sites that used the notification form of treatment for ILTB. The form was used as a tool for data collection. The research period was between July 2009 and August 2010. 144 individuals were found in treatment for ILTB, and 140 (97,22%), the majority of nomination was TB contacts, 46 (31.94%) abandoned the treatment, and 98 (68.06%) completed the treatment. Most individuals were contacts of TB, and when was analyzed the situation of the bacilloscopy (BAAR) of the index case of contact, the majority of both the group that left, and the group that completed treatment, 97,62% e 87,91% (p=0,06), respectively, were positive. Regarding the type of contact, the home was the most frequent, and also between the two groups, both those abandoned and those who completed, totaled 81,82% e 84,21% (p=0,72), respectively, followed by others, who were uncles, grandparents , who lived nearby. Children and teenagers were evaluated mostly had scar of BCG (Bacillus of Calmette and Guérin) present, and had mostly a normal chest X-ray. Teenagers (&#8805; 10 years old), were checked if they had more chances to leave the treatment of ILTB, comparing with less than 10 years old, because the same need caregivers help for use of medication, however, the majority of both groups, concluded the treatment, teenagers 75% and children 64,13% (p=0.17). This study reinforces the need to control the contacts of patients, identifying priority children and teenagers and developing strategies for treatment adherence. The study can also stimulate the improvement of notification s system since, despite the orientation of MOH, its implementation has not yet been standardized

Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>Os profissionais da área da saúde formam um dos grupos mais vulneráveis à infecção pelo Mycobacterium tuberculosis (Mtb). Segundo estimativas da Organização Mundial de Saúde (OMS), 8,8 milhões de pessoas estavam infectadas pelo Mtb e ocorreram 1,4 milhão de óbitos por tuberculose (TB) em 2010. A identificação de pessoas com Infecção Latente Tuberculosa (ILTB) é considerada pela OMS como uma prioridade no controle da doença, especialmente em países em desenvolvimento em que a incidência da doença ativa tem apresentado redução. O objetivo do presente trabalho foi avaliar, no Brasil, o custo-efetividade dos testes Prova Tuberculínica (PT) e Quantiferon TB Gold-In-Tube (QTF-GIT) no diagnóstico e tratamento da ILTB em profissionais de saúde atuantes na atenção básica, sob a perspectiva do Sistema Único de Saúde (SUS), comparando cinco estratégias que incluem o QTF-GIT, distintos pontos de corte para a PT e uso sequencial dos dois testes; e analisar o impacto do tabagismo sobre o risco de ILTB entre os profissionais de saúde, destacando-se a categoria da Enfermagem. Foi realizada uma avaliação econômica completa do tipo custo-efetividade, conduzida considerando uma coorte hipotética de 10.000 profissionais de saúde atuantes na atenção básica, com horizonte temporal restrito a um ano. Um modelo analítico de decisão, caracterizado por uma árvore de probabilidades de eventos, foi desenvolvido utilizando o software TreeAge ProTM 2013 para simular os resultados clínicos e impactos econômicos em saúde da nova tecnologia diagnóstica (QTF-GIT) versus a PT tradicional. Esse modelo simulou cinco estratégias diagnósticas para detecção e tratamento da ILTB: (a) PT, usando ponto de corte de 5mm; (b) PT, usando ponto de corte de 10 mm; (c) teste QTF-GIT; (d) PT, com ponto de corte de 5mm, seguida de teste QTF-GIT quando PT positiva; (e) PT, com ponto de corte de 10mm, seguida de teste QTF-GIT quando PT positiva. Foi realizada análise de sensibilidade determinística univariada. Na determinação dos fatores associados à ILTB, foi elaborado um modelo de regressão logística múltipla com seleção hierarquizada, utilizando o software Stata. A estratégia mais custo-efetiva foi a PT no ponto de corte &#8805;10mm, considerando como medida de desfecho tanto o número de indivíduos corretamente classificados pelos testes assim como o número de casos de TB evitados. A utilização isolada do QTF-GIT revelou-se a estratégia de menor eficiência, com RCEI= R$ 343,24 por profissional corretamente classificado pelo teste. Encontrou-se risco à ILTB significantemente maior para sexo masculino [OR=1,89; IC 95%:1,11-3,20], idade &#8805; 41 anos [OR=1,56; IC 95%: 1.09-2,22], contato próximo com familiar com TB [OR=1,55; IC 95%: 1.02-2,36], status do tabagismo fumante [OR=1,75; IC 95%: 1.03-2,98] e categoria profissional da Enfermagem [OR=1,44; IC 95%: 1.02-2,03]. Concluiu-se que a PT no ponto de corte de 10mm é a estratégia diagnóstica mais custo-efetiva para ILTB entre os profissionais de saúde na atenção básica e que a ILTB está associada ao hábito do tabagismo e à categoria profissional de Enfermagem.<br>Health professionals form one of the groups most vulnerable to infection by Mycobacterium tuberculosis (Mtb). According to estimates by the World Health Organization (WHO), 8.8 million people were infected with Mtb and were 1.4 million deaths from TB in 2010. The identification of persons with Latent Tuberculosis Infection (LTBI) is considered by WHO as a priority in the control of disease, especially in developing countries where the incidence of active disease has shown reduction. The aim of this study was to evaluate, in Brazil, the cost-effectiveness of tests Tuberculin Skin Test (TST) and Quantiferon TB Gold-In-Tube (QFT-GIT) in the diagnosis and treatment of LTBI in health professionals working in primary care from the perspective of SUS, comparing five strategies that include the QFT -GIT, different cutoff points for TST and sequential use of two tests; and analyze the impact of smoking on the risk of LTBI among health professionals, highlighting the category of Nursing. A full economic assessment of the type cost-effectiveness was performed, conducted considering a hypothetical cohort of 10,000 health professionals working in primary care, with limited time horizont of one year. A decision analytical model, characterized by a tree of probabilities of events, was developed using the TreeAge ProTM software 2013 (TreeAge Software Inc, Williamstown, MA, USA) to simulate the clinical and economic impacts on health of new diagnostic technology (QFT -GIT) versus the traditional TST. This model simulated five diagnostic strategies for detection and treatment of LTBI (a) TST, using a cut-off of 5 mm; (B) TST, using 10 mm cut-off currently recommended by the TNP; (C) QFT-GIT test; (D) TST, with a cut-off of 5 mm, followed by QFT-GIT test when positive TST; (E) TST, with a cut-off point of 10 mm, followed by QFT-GIT test when positive TST. Univariate deterministic sensitivity analysis was performed to assess the robustness of the results. In determining the factors associated with LTBI, a multiple logistic regression model with hierarchical selection was made, using the Stata software. TST strategy at the cut-off &#8805; 10mm was the most cost-effective strategy, while the QFT-GIT alone was the most effective strategy, but showed higher cost. It was found to significantly greater risk for LTBI male [OR = 1.89; 95% CI: 1.11 to 3.20], age &#8805; 41 years [OR = 1.56; 95% CI: 1.09-2,22], close contact with a family with TB [OR = 1.55; 95% CI: 1.02-2,36], the smoker smoking status [OR = 1.75; 95% CI: 1.03-2,98] and professional nursing category [OR = 1.44; 95% CI: 1.02-2,03]. It was concluded that TST in 10mm cut-off is the diagnostic strategy more cost-effective for LTBI among health professionals in primary care and that LTBI is associated with the smoke and professional category nurse.

Mtb is able to establish a chronic asintomatically infection mainly in the lung and the balance between host immune response and the mycobacteria plays a fundamental role in the control of the Mtb replication . Although the immune response to Mtb has been deeply studied, as described in the previously chapters, the host factors that leads to the development to active TB disease are not fully understood. However, on the base of immunogical findings on Mtb infection, it is possible to speculate that the containment of the latent Mtb needs an acquired cellular response with specific characteristics of immune surveillance, differently contrasting the replicating Mtb requires effector and cytotoxic proprierty. Objective of the present study is to take a picture of the immunological status of patients with Mtb infection, characterizing their Mtb specific immune response, in order to find a correlation with the different stages of Mtb infection. In the chapter 5 it is described the use of several cytometric approaches to evaluate the surface expression of the activation marker CD27 on Mtb-specific CD4+ T-cells, as a tool to diagnose active TB and LTBI. The chapter 6 is focused on flow cytometric characterization of the specific CD4 and CD8 T-cell responses to Mtb antigens contained within the QuantiFERON®-TB Gold Plus (QFT-Plus). QFT-Plus is the new generation of QuantiFERON-TB Gold In-Tube test (QFT-GIT) to identify the latent tuberculosis infection, it includes two tubes called TB1 and TB2 tubes which contain selected Mtb peptides designed to stimulate both CD4 and CD8 T-cells. Aim of the study was to analyze if the immune response to TB1 and TB2 stimulation could or not highlight differences between different TB stages. In the chapter 7, QFT-Plus performance was compared with that one of QFT-GIT in a cross sectional study of individuals with LTBI, active TB or treated for TB in the past. In this study, we wanted also to evaluate if the different ability to

博士<br>國立臺灣大學<br>流行病學與預防醫學研究所<br>103<br>Background: Predicting the risk of tuberculosis (TB) in people living with HIV (PLHIV) using a single test is currently not possible. We aimed to develop and validate a clinical algorithm, using baseline CD4 cell counts, HIV viral load (pVL), and interferon-gamma release assay (IGRA), to identify PLHIV who are at high risk for incident active TB in low-to-moderate TB burden settings where highly active antiretroviral therapy (HAART) is routinely provided. Methods: A prospective, 5-year, cohort study of adult PLHIV was conducted from 2006 to 2012 in two hospitals in Taiwan. HAART was initiated based on contemporary guidelines (CD4 count <= 350/μL). Cox regression was used to identify the predictors of active TB and to construct the algorithm. The validation cohorts included 1455 HIV-infected individuals from previous published studies. Area under the receiver operating characteristic (ROC) curve was calculated. Results: Seventeen of 772 participants developed active TB during a median follow-up period of 5.21 years. Baseline CD4 < 350/μL or pVL ≥ 100,000/mL was a predictor of active TB (adjusted HR 4.87, 95% CI 1.49-15.90, P=0.009). A positive baseline IGRA predicted TB in patients with baseline CD4 ≥ 350/μL and pVL < 100,000/mL (adjusted HR 6.09, 95% CI 1.52-24.40, P=0.01). Compared with an IGRA-alone strategy, the algorithm improved the sensitivity from 37.5% to 76.5%, the negative predictive value from 98.5% to 99.2%. Compared with an untargeted strategy, the algorithm spared 468 (60.6%) from unnecessary TB preventive treatment. Area under the ROC curve was 0.692 (95% CI: 0.587-0.798) for the study cohort and 0.792 (95% CI: 0.776-0.808) and 0.766 in the 2 validation cohorts. Conclusions: A validated algorithm incorporating the baseline CD4 cell count, HIV viral load, and IGRA status can be used to guide targeted TB preventive treatment in PLHIV in low-to-moderate TB burden settings where HAART is routinely provided to all PLHIV. The implementation of this algorithm will avoid unnecessary exposure of low-risk patients to drug toxicity and simultaneously, reduce the burden of universal treatment on the healthcare system.

碩士<br>國防醫學院<br>公共衛生學研究所<br>104<br>Background and Objective :Taiwan new determine the annual number of cases of tuberculosis about more than eleven thousand, and about 600 to 700 people died of tuberculosis, whether new cases or number of deaths, all for the nation's first legal infectious diseases. Early detection of patients with latent tuberculosis infection, and left untreated, can prevent its conversion to active TB patients, resulting in more severe infections. The US Food and Drug Administration approval in 2007 QuantiFERON-TB Gold In-Tube test (QFT-GIT) the use, not only sensitivity and specificity are higher than the TST, and not interfere with BCG. This study aimed to investigate the employees of a latent tuberculosis infection situation and risk factors, the study period from 103 in March to September. Methods : This study is cross-sectional study, the study period from 103 in March to September , the object is at the time of the annual medical examination of employees voluntarily participate in a study. The use of structured questionnaire latent tuberculosis infection risk factors, and collect blood specimen using QFT-GIT test latent tuberculosis infection screening. Statistical methods for the multiple logistic regression. After adjusting for potential confounding factors, investigate QFT-GIT positive screening results are presented in the risk factors. Result: The study was completed questionnaires and blood tests were 803 people, including 71 positive .The results showed that the prevalence of certain employees of latent tuberculosis infection 8.84%, the OR showed that congregate subjects increased the risk of LTBI by 2.72 fold (OR=2.72,95% CI = 1.42-5.20); the OR showed that inmates with people increased the risk of LTBI by 2.49 fold (OR=2.49, 95% CI = 1.82-7.51). Conclusion: The groups of clustering in the longtime to live and work often likely to cause TB infection, it is recommended for these high-risk groups, should be regularly implement screening for latent tuberculosis infection. Keywords: screening, latent tuberculosis infection , QFT-GIT

碩士<br>輔仁大學<br>應用統計學研究所<br>94<br>The study is a survey of the Tuberculosis (TB) accumulated infection in a campus of Jia-Yi County in 2003. In order to learn about the prevalence and the potential risk of TB in campus, CDC in Taiwan underwent a Tuberculin Skin Test (TST) on teachers and students in the selected campus in March and April of the 2004 and 2005, respectively. Questionnaire on the personal contact history was conducted to take a comprehensive view of the risk contact factors and the infection reasons. The result of analysis revealed: 1. The TST status correlates to the factors of schools, gender, age, number of Bacille Calmette-Guerin (BCG) scars, frequency of going to Internet-Café and coaching schools. 2. People with scars have different positive reactivity in 1994 &1995. The reason is the boosting effect by double BCG inoculation and TST. 3. Estimates of the annual risk of tuberculous infection (ARTI) are 2.53-4.11%, and this is higher than the result (1.11%) of census on the first grade students in the elementary school in 2004. This shows that they have higher infection risk. 4. The combination of factors of the reactivity to the TST, the female, never going to Internet-Café, going to coaching school, and age≦15-19 years, is the group having the greatest percentage (24%) of the negative reaction. To the contrary, the group that age≧15-19 years, only occupies 2.1% of the negative reaction. As a result, this group has the highest possibility of latent infection. 5. The reactivity prevalence and statistically significant odds ratio (OR) show: male (OR =0.88), ≧40 years old (OR =3.24), with BCG (OR =1.66), going to the Internet-Café (OR =0.90), going to the coaching school (OR =0.80). Consequently, it is recommended to take a regular follow-up on people having the TST positive within five years.

碩士<br>國防醫學院<br>公共衛生學研究所<br>100<br>Rationale: Tuberculosis (TB) has been the highest morbidity and mortality infectious disease in Taiwan for several years. Male has higher morbidity and mortality than those of female. The morbidity rate increases from the age-group—15~24 years old. Screening and treatment for latent TB infection (LTBI) among young men may result in preventing an active tuberculosis disease. There are two methods to detect a LTBI: tuberculin skin test (TST) and interferon-gamma release assays (IGRAs). However, TST may produce a false-positive due to being confounded by Bacille Calmette-Guérin (BCG), whereas IGRAs detect specific proteins early secreted antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10). Aims: To assess the prevelance and risk factors for LTBI among army recruits. Methods: We conducted a cross-sectional study from 2010/01/01 to 2011/12/31. This study has been approved by the institute review board of the Tri-Service General Hospital, Taipei city, Taiwan. Recruits whose age ≧ 20 years old were invited to participate in this study, including to denote 2 ml whole blood for IGRA test and answer a structured questionnaire. Multiple logistic regression with stepwise selection was applied to evaluate the association of interests and control potential confounders by using SPSS 16.0 v. Results: In A, B, and C recruit training centers, positive rates for IGRA were 7.44% (64/860), 4.87% (6/123), and 1.90% (4/210) respectively. After controlling the confounders, we found that living in eastern Taiwan (OR=2.35, 95%CI:1.28~4.29), TB history (OR=8.53, 95%CI:1.49~48.7), smoking (OR= 3.49, 95%CI:1.76~6.89), coffee drinker (OR=1.84, 95%CI:1.04~3.26), and has been to PUB during the last 6 months (OR=1.82, 95%CI:1.01~3.29) were associated with LTBI. Conclusions: In conclusion, to prevent a TB outbreak in the military, we suggest to have a latent tuberculosis screening and treatment program for recruits from eastern Taiwan, as well as a professional TB health education will be needed for all recruits.

An estimated 9 to 14 million persons in the United States have latent tuberculosis infection (LTBI) and are therefore at risk for progression to active disease. Diagnosis and treatment for LTBI has been identified by the Centers for Disease Control and Prevention (CDC) and the Institute of Medicine as a major strategy for elimination of tuberculosis (TB) in the U.S. Approximately 200,000 - 300,000 Americans are treated for LTBI each year. This dissertation investigates patient characteristics that are associated with LTBI treatment completion and assesses the impact of a peer-based experimental intervention on adherence to, and completion of, LTBI treatment. A review of the literature (Chapter 2) demonstrates that LTBI treatment completion rates in the U.S. and Canada generally fall below established targets and have been reported to range from 20 to 65% for a 6-month course of self-administered treatment. Associations between patient factors, clinic facilities, or treatment characteristics and adherence to LTBI treatment were found to be inconsistent across studies. Additionally, adherence interventions have been developed but no single intervention has shown consistent effectiveness. This suggests that a 'one-size-fits-all' approach to LTBI treatment adherence is not likely to succeed across all settings. The remainder of the dissertation focuses on predictors of LTBI treatment completion and the impact of a peer-based experimental intervention on adherence to, and completion of, LTBI treatment in two separate randomized controlled trials. Data for these analyses are drawn from two sequential randomized controlled trials designed to compare a peer-based intervention to usual care for ensuring completion of treatment for LTBI in an urban clinic setting: the Pathways to Completion Study (recruitment from 1996 through 2000) as well as from the Tuberculosis Adherence Partnership Alliance Study (TAPAS ) (recruitment from 2002 through 2005). Chapter 3 describes the change in demographic, social, and behavioral characteristics between the two study populations. The first analysis (Chapter 4) examines predictors of LTBI treatment completion in this population. Our results suggest that foreign birth, homelessness, marriage, and alcohol or drug use all influence completion of TLTBI through complex interactions. Overall, married persons had better completion rates, but married foreign-born patients were substantially more likely to complete therapy than unmarried foreign-born patients. Similarly, alcohol users were less likely to complete therapy, but homeless alcohol users were more likely to complete treatment than other homeless patients. The latter is probably an artifact of our clinic population, which includes patients from alcohol and substance abuse rehabilitation programs. Residence in such programs may have a positive effect on treatment completion. Race/ethnicity did not appear to be associated with treatment completion, although the differences between the two study populations made this difficult to assess. Following from this, an analysis of the effectiveness of a peer-based experimental intervention on adherence to, and completion of, LTBI treatment in two separate randomized controlled trials (Chapter 5) finds peer support experimental intervention to be very effective in the Pathways population but not in the TAPAS population where completion rates increased substantially for both the intervention and control groups. The power for detecting an intervention effect in TAPAS was reduced by the higher than expected completion rates in both groups; however, the effect of the TAPAS intervention is statistically significant in the adherence model. Adherence analysis in TAPAS suggests that it is important to intervene early in the treatment as the first two months of treatment present a danger period where patients tend to default treatment. The most common reasons reported for not adhering to treatment were forgot, ran out of medications, and other priorities. Identifying reasons for missing medications can suggest possible foci for interventions in the early months, such as weekly reminders to take the medications and ensuring that prescriptions are refilled on schedule. Taken together, the findings of this research have significant implications for improving adherence to and completion of LTBI treatment. Currently, the primary intervention for improving LTBI adherence consists of educational programs to increase knowledge and modify attitudes. Our findings suggest that tangible assistance would be more effective in encouraging treatment completion. Additionally, adherence analysis in TAPAS suggests that it is important to intervene early in the treatment. Close follow-up of patients during the first two months of treatment, with prompt intervention to encourage completion among those stopping treatment, may yield better outcomes and reduce costs over the long term.

Mycobacterium tuberculosis, the etiological agent of tuberculosis, has adapted with the host environment and evolved to survive in harsh conditions in the host. The pathogen has successfully evolved strategies not only to evade the host immune system but also to thrive within the host cells. Upon infection, the pathogen is either cleared due to the host immune response, or it survives and causes active tuberculosis (TB) infection. In a number of cases however, the pathogen is neither killed nor does it actively proliferate, but it remains dormant in the host until the environment becomes favorable. This dormant state of pathogen is responsible for latent TB infection (LTBI). WHO reports indicated that as much as a third of the whole world’s population is exposed to the pathogen, of which a significant proportion could be latently infected (WHO report, 2015). These individuals do not show symptoms of active TB infection and hence are difficult to detect. The latent TB infected (LTBI) individuals serve as a reservoir for the pathogen, which can lead to epidemics when the conditions change. Hence, it is necessary to understand the host -pathogen interactions during LTBI, as this might provide clues to developing new strategies to detect and curb a latent infection. Host-pathogen interactions are multifaceted, in which both species attempt to recognize and respond to each other, all of these through specific molecules making distinct interactions with the other species. The outcome of the infection is thus decided by a complex set of host-pathogen interactions. The complexity arises since a large number of molecular components are involved, also multiplicity of interactions among these components and due to several feedback, feed forwards or other regulatory or influential loops within the system. The complexity of biological systems makes modeling and simulation an essential and critical part of systems– level studies. Systems biology studies provide an integrated framework to analyze and understand the function of biological systems. This work addresses some of these issues with an unbiased systems-level analysis so as to identify and understand the important global changes both in the host and in the pathogen during LTBI. The broad objectives of the work was to identify the key processes that vary in the host during latent infection, the set of metabolic reactions in the host which can be modulated to control the reactivation of infection, global adaptation in Mycobacterium tuberculosis (Mtb) and then to utilize this knowledge to identify strategies for tackling latent infection. A review of literature of the current understanding of latency from the pathogen and the host perspective is described in chapter 1. From this, it is clear that most available studies have focused on the role of individual molecules and individual biological processes such as granuloma formation, toll-like receptor signaling, T cell responses as well as cytokine signaling, in either initiating or maintaining a latent infection, but there is no report till date about whether and how these processes are connected with each other. While transcriptome based studies have identified lists of differentially expressed genes in LTBI as compared to healthy controls, no further understanding is currently available for many of them, regarding the processes they may be involved in and what interactions they make, which may be important for understanding LTBI. The first part of the work is a systematic meta-analysis of genome-scale protein interaction networks rendered condition-specific with transcriptome data of patients with LTBI, which has provided a global unbiased picture of the transcriptional and metabolic variations in the host and in the pathogen during the latent infection. To start with, publicly available gene expression data related to LTBI, active TB and healthy controls were considered. In all, 183 datasets summing up to 105 LTBI, 41 active TB and 37 healthy control samples were analyzed. (Chapter 2). Standard analysis of the transcriptome profiles of these datasets indicated that there was zero overlap among them and that not a single gene was seen in common among all datasets for the same condition. An extensive human protein-protein interaction network was constructed using information available from multiple resources that comprehensively contained structural or physical interactions and genetic interactions or functional influences. Nodes in this network represented individual proteins and edges represented interactions between pairs of nodes. The identity of each node and the nature of interaction of each edge along with the type of evidence that was used as the basis for drawing the edge, was collated for the network. The gene expression data was integrated into the human protein-protein interaction (PPI) network for each condition, which essentially had weighted nodes and directed edges, specific to that condition, from which specific comparative networks were derived. The highest ranked perturbations in LTBI were identified through a network mining protocol previously established in the laboratory. This involved computing all versus all shortest paths on the comparative network, scoring the paths based on connectedness and various centrality measures of the nodes and the edges and finally ranking the paths based on the cumulative path scores. Intriguingly, the top-ranked set of perturbations were found to form a connected sub-network by themselves, referred to as a top perturbed sub-network (top-net), indicating that they were functionally linked or perhaps even orchestrated in some sense. Th17 signaling appears to be dominant. About 40 genes were identified in the unique set of LTBI condition as compared to the active TB condition, and these genes showed enrichment for processes such as apoptosis, cell cycle as well as natural killer cell mediated toxicity. Construction and analysis of a miRNA network indicated that 32 of these have strong associations with miRNA explaining the role of the latter in controlling LTBI. 3 other genes from the top-net are already established drug targets for different diseases with known drugs associated with them, which are BCL2, HSP90AA1 and NR3C1. These 3 proteins can be explored further as drug targets in LTBI whose manipulation using existing drugs may result in inhibiting the underlying biological process and thereby result in disturbing the state of latency. As a second objective, global variations in the host transcriptome were identified during ascorbic acid induced dormancy (Chapter 3). Ascorbic acid or Vitamin C is a nutrient supplement required in the diet. This organic compound has a known antioxidant property, as it is known to scavenge the free radicals. In a recent study, Taneja et al, demonstrated that Vitamin C could induce dormancy in Mtb. On similar lines, experiments were done in THP-1 cells infected with Mtb to determine the host responses during ascorbic acid (AA) induced dormancy. The raw gene expression data was provided by our collaborator Prof. Jaya Tyagi that included 0 hour, 4 days and 6 days time points with infection and vitamin C versus infection alone or vitamin C alone as controls. The transcriptome data was normalized and integrated into the human PPI network as described for the meta-analyses. It was experimentally determined that ascorbic acid induces dormancy in 4 days post infection. The top-ranked paths of perturbation were analyzed and compared for three different conditions: (i) uninfected condition, (ii) AA treated and infected condition, and (iii) AA, isoniazid and infected condition. The dormant pathogen is known to be drug-tolerant and thus as a marker for the state of dormancy, the lack of effect of isoniazid is also monitored in the infected host cells. The analysis revealed that there were some broad similarities as compared to LTBI from patient samples but AA induced dormancy in cell lines stood out a separate group indicating that there were significant differences such as involving Interferon Induced Transmembrane Proteins (IFITMs), vacuolar ATPase as well as GDF15, which belongs to TGF-beta signaling pathway. The highest ranked perturbed paths contained genes involved in innate immune responses of which ISG15, IFITMs, HLAs and ATPases emerge as the most altered in the dormant condition. CCR7 emerges as a key discriminator, which is subdued in the latent samples but highly induced in infection conditions. Pathway-based analysis of different conditions showed that oxidative stress, glutathione metabolism, proteasome degradation as well as type II interferon signaling are significantly up-regulated in AA induced dormancy. The dormant bacteria reside in the host cells and are known to modulate the host metabolism for their own benefit. So, the third objective was to understand the metabolic variations in the host during LTBI (Chapter 4). A genome-scale metabolic (GSM) model of alveolar macrophage was used in this study. The metabolic model contains information of the reactions, metabolites and the genes encoding enzymes that catalyze a particular reaction. Flux balance analysis (FBA), a constraint-based metabolic modeling method, is used for analyzing the alterations in the metabolism under different infection conditions. In order to mimic the physiological condition, gene expression data was used for constraining the bounds of the reactions in the model. Two different expression studies were used for analysis: GSE25534 (from Chapter 2) and ascorbic acid induced dormancy (Chapter 3). The analysis was carried out for latent TB versus healthy control and latent TB versus active TB to identify the most altered metabolic processes in LTBI. Differences in fluxes between the two conditions were calculated. A new classification scheme was devised to categorize the reactions on the basis of flux differences. In this chapter, higher fluxes in LTBI condition were identified for reactions involved in transport of small metabolites as well as amino acids. Solute carrier proteins responsible for the transport of the metabolites were identified and their biological significance is discussed. Reduced glutathione (GSH), arachidonic acid, prostaglandins, pantothenate were identified as important metabolites in LTBI condition and their physiological role has been described. Sub-system analysis for different conditions shows differential regulation for arachidonic acid metabolism, fatty acid metabolism, folate metabolism, pyruvate metabolism, glutathione metabolism, ROS detoxification, triacylglycerol synthesis and transport as well as tryptophan metabolism. From the study, transporter proteins and reactions altered during LTBI were identified, which again provide clues for understanding the molecular basis of establishing a latent infection. Mycoabcterium tuberculosis is known to undergo dormancy during stress conditions. In this chapter, the main objective was to identify the global variations in the dormant Mtb (Chapter 5). To carry out the analysis, the Mtb PPI network was constructed using information from available resources. Gene expression data of two different dormancy models, Wayne growth model and multiple-stress model, were used for the study. To identify the key players involved in reversal of dormancy, the transcriptome data of reaeration condition was also used. In this study, the Max-flow algorithm was implemented to identify the feasible paths or flows in different condition. The flows with higher scores indicate that more information is traversed by the path, and hence is important for the study. From the analysis of Wayne growth model (hypoxia model), important transcriptional regulators such as SigB, SigE, SigH, regulators in the two-component system such as MprA, MtrA, PhoP, RegX3 and TrcR were identified in stress condition. Multiple-stress model studied the growth of bacteria in low oxygen concentration, high carbon dioxide levels, low pH and nutrient starvation. The gene expression data was integrated in the Mtb PPI network and implementation of Max-flow algorithm showed that MprA, part of the MprA-MprB two-component system, is involved in the regulation of persistent condition. WhiB1 also features in the paths of dormant condition and its role in persistence can be explored. In reaeration model, WhiB1 and WhiB4 are present in the top flows of this condition indicating that the redox state is perturbed in the pathogen and the interactions of these proteins are important to understand the reversal of dormant condition. From the study, Rv2034, Rv2035, HigA, Rv1989, Rv1990 and Rv0837 proteins belonging to toxin-antitoxin systems were also identified in the dormant bacteria, indicating their role in adaptation during stress condition. The role of Rv2034 has been studied in persistence, but the function of other proteins can be analyzed to provide new testable hypotheses about the role of these proteins in dormancy. Thus, the flows or paths perturbed during dormancy were identified in this study. To get a better understanding of the metabolic network active in mycobacteria under different conditions, experiments were performed in Mycobacterium smegmatis MC2 155. The non-pathogenic strain of genus Mycobacteria, Mycobacterium smegmatis, is used as a surrogate to carry out molecular biology studies of Mtb. Mycobacterium smegmatis MC2 155 (Msm) is the commonly used laboratory strain for experimental purpose. In order to obtain a clear understanding of how comparable are the metabolic networks between the virulent M. tuberculosis H37Rv and the model system Msm, the latter model is first studied systematically. In Chapter 6, first the functional annotation of the Msm genome was carried out and the genes were categorized into different Tuberculist classes based on homology with the Mtb genome. A high-throughput growth characterization was carried out to characterize the strain systematically in terms of different carbon, nitrogen or other sources that promoted growth and thus served as nutrients and those that did not, together yielding a genome-phenome correlation in Msm. Gene expression was measured and used for explaining the observed phenotypic behavior of the organism. Together with the genome sequence, the transcriptome and phenome analysis, a set of about 257 different metabolic pathways were identified to be feasible in wild-type Msm. About 284 different carbon, nitrogen source and nutrient supplements were tested in this experiment and 167 of them supported growth of Msm. This indicates that the compounds enter the cells and are metabolized efficiently, thus yielding similar phenotypes. The expressed genes and metabolites supporting growth were mapped to the metabolic network of Msm, thus helping in the identification of feasible metabolic routes in Msm. A comparative study between Msm and Mtb revealed that these organisms share similarity in the nutrient sources that are utilized for growth. The study provides experimental proof to identify the feasible metabolic routes in Msm, and this can be used for understanding the metabolic capability in the two organisms under different conditions providing a basis to understand adaptations during dormancy. In the last part of the work presented in this thesis, the metabolic shift in the pathogen was studied using a genome-scale metabolic model of Mtb (Chapter 7). The model contains information of the reactions, metabolites and genes involved in the reactions. Flux balance analysis (FBA) was carried out by integrating normalized gene expression data (Wayne model and multiple-stress model transcriptome considered in Chapter 5) to identify the set of reactions, which have a higher flux in the dormant condition as compared to the control replicating condition. Glutamate metabolism along with propionyl CoA metabolism emerge as major up-regulated processes in dormant Mtb. Next, with an objective of identifying essential genes in dormant Mtb, a systematic in silico single gene knock-out analysis was carried out where each gene and it's associated reaction was knocked out of the model, one at a time and the ability of the model to reach its objective function assessed. About 168 common genes in Wayne model and multiple-stress model were identified as important in Mtb after the knockout analysis. Essentiality is in essence a systems property and requires to be probed through multiple angles. Towards this, essential genes were identified in Mtb using a multi-level multi-scale systems biology approach. About 283 genes were identified as essential on the basis of combined analysis of transcriptome data, FBA, network analysis and phyletic retention studies in Mtb. 168 genes identified as important in dormant Mtb were compared with 283 essential genes and about 91 genes were found to be essential. Finally, among the set of essential genes, those that satisfy other criteria for a drug target were analyzed using the list of high-confidence drug targets of Mtb available in the laboratory along with their associated drug or drug-like molecules. 38 out of the 168 important genes in Mtb were found to have one or more drugs associated with them from the DrugBank database. Colchicin-Rv1655, Raloxifene-Rv1653, Bexarotene-Rv3804, Rosiglitazone-Rv3804 are top-scoring drug-target pairs that can be explored for killing dormant bacilli. The study has thus been useful in identifying important proteins, reactions and drug targets in dormant Mtb. In summary, the thesis presents a comprehensive systems-level understanding of various aspects of host responses and pathogen adaptation during latent TB infection. Key host and pathogen factors involved in LTBI are identified that serve as useful pointers for deriving strategies for tackling a latent infection.

碩士<br>國立臺灣大學<br>流行病學與預防醫學研究所<br>107<br>Background In contrast to the countries with low incidence of tuberculosis (TB), strategies of controlling Tuberculosis (TB) in those countries with moderate disease burden, the adoption of WHO guideline through passive case finding and chemoprevention for latent tuberculosis infection (LTBI) through active investigation for contact tracing is not sufficient to reach the goal of disease prevention. The alternative is the use of screening as a secondary prevention with the conventional Tuberculin Skin Test (TST) and the recently proposed Interferon-gamma Release Assay (IGRA) aimed at early detection and treatment of TB arising from among LTBI in average-risk population followed by the provision of chemoprophylaxis to decrease the risk of further progression to clinical TB. Given the costs incurred in screening earlier and the effectiveness of averting TB cases accrued later, economic evaluation plays an important role in decision-making for such kinds of screening strategy, which been barely addressed. Aims This thesis aimed at assessing the efficacy and cost-effectiveness of applying Tuberculin Skin Test (TST), IGRA, and the combination of the two compared with no screen together with the consideration of current context of TB prevention strategy in Changhua. Material and Methods The forces of natural evolution of tuberculosis from susceptible, LTBI, reinfection, clinical TB resulting from exogenous and endogenous sources, to TB death was first derived from the empirical data of TB surveillance registry, contact investigation registry, and community-based screening samples with the consideration of the effect of age, sex. The diagnostic characteristics of TST, IGRA, and the combination of the two were derived by using the data from Changhua integrated community-based screening. Based on the parameters of TB evolution, the effectiveness and cost-effectiveness for the four scenarios of no screen, TST screening, IGRA screening, and screening by using TST combined with IGRA were assessed by using Markov decision tree under the context of TB prevention in Changhua. The incremental cost-effectiveness ratios (ICERs) with deterministic and probabilistic approach were estimated. Results The incidence of TB in 2016 was 50 per 100,000. Regarding the force of TB infection rate and conversion rate, subjects with positive IGRA had higher risks on both rates. Male also had higher risk in these two rates. While the elderly had a higher risk for the progression to clinical TB from LTBI, the risk of LTBI was higher for the young. The case-fatality rate of TB in Changhua was around 20%. By using the parameters derived from the empirical data in Changhua, the cost-effectiveness of the population-based screening strategies using TST and IGRA were assessed. The combination uses of TST and IGRA provides a higher efficacy in averting TB cases compared with no screen. Regarding the cost-effectiveness of TB case averted, the ICER for prevention one TB case was estimated as NT 35,966, NT 40,973, NT 45,748, and NT 34,404 for the screening strategy using TST, IGRA, the combination of the two in parallel and that in serial, respectively with the probability of being cost effective of 85.0%, 78.5%, 77.0%, and 86.0%, respectively, based on the NT 60,000 threshold value of wiliness-to-pay. The ICER for life-years gain was NT 39,439, NT 44,284, NT 55,086, and NT 37,190 for TST screen, IGRA screen, the screen with the combination of TST and IGRA in parallel, and that in serial, respectively. The NT 60,000 willing-to-pay threshold gives the probability of being cost-effective around 60% for the four strategies compared with no screen. Conclusion The strategy of screening for LTBI in an average-risk population by using TST, IGRA and TST combined IGRA is effective in averting TB cases through the early identification of LTBI subjects followed by the chemoprophylaxis of INH. Keywords: population-based screen, LTBI, TST, IGRA (QFT-GIT), cost-effectiveness analysis

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014<br>The high incidence of latent tuberculosis infection (LTBI) is recognized as one of the barriers to eradication of tuberculosis (TB) worldwide. Latent cases of the disease account for a hidden pool of potentially infectious subjects within a community who are desirable targets for early screening. While the impact of contact transmission on the general burden of TB within a population is unknown, a recent meta-analysis estimated the overall prevalence of LTBI among high-income countries to be as high as 28%1, making this an important subgroup of patients at risk for infection and disease. To date there is no gold-standard method for diagnosing LTBI, and it is impossible to distinguish between remote and recent infection. Definition of LTBI is itself controversial. Tuberculin skin testing (TST) and Interferongamma release assays (IGRA) are the tools widely accepted for LTBI screening. Though IGRAs have been suggested to more accurately detect LTBI compared to TST, several questions have been raised about the agreement, specificity and sensitivity of both tests, as well as their predictive values and window periods for conversion. Because we acknowledge the need for a better means of differentiating between recent and remote infection in order to appropriately screen highrisk individuals, we conducted a literature review on this subject that included original papers, systematic reviews, meta-analyses, and opinion and perspective articles. The aim of this communication is to give a comprehensive, evidence-based perspective on the currently preferable approach to these patients.<br>A elevada incidência da infecção latente por tuberculose (LTBI) é reconhecida como um dos grandes obstáculos à erradicação da tuberculose (TB) no mundo. Casos latentes constituem um reservatório oculto de indivíduos potencialmente infecciosos numa comunidade que são, por isso, alvos desejáveis para detecção precoce. Apesar de o verdadeiro impacto da transmissão entre contactos na epidemiologia global da TB não ser conhecido, uma meta-análise recentemente concluiu que a prevalência da LTBI nos países desenvolvidos pode chegar aos 28%1, tornando este um importante subgrupo de doentes em risco de doença e transmissão. Até à data, não existe um método gold standard para o diagnóstico de LTBI e é impossível distinguir entre infecção remota e recente. A definição de LTBI é, em si mesma, controversa. O teste cutâneo da tuberculina (TST) e os testes de doseamento da libertação de interferão-gama (IGRA) são largamente utilizados para o controlo da LTBI. Apesar de o IGRA ser considerado superior ao TST na sua eficácia em detectar LTBI, várias dúvidas se levantam em relação à concordância entre os testes, à sua especificidade, sensibilidade, valores preditivos e períodos de conversão. Reconhecendo as limitações actuais e a necessidade de novos e melhores métodos para a detecção precoce da infecção latente por tuberculose nos contactos com exposição recente, desenvolvemos uma revisão de literatura que incluiu artigos originais, revisões sistemáticas, meta-análises, e artigos de opinião e perspectiva. O objectivo deste trabalho é a compilação e análise da evidência actualmente disponível sobre a mais eficaz abordagem a estes doentes.

碩士<br>國防醫學院<br>公共衛生學研究所<br>99<br>Rationale: Health care workers (HCWs) taking care of and dealing with TB patient’s samples, and therefore become are one of the groups at high risk of Mycobacterium tuberculosis infection through occupational exposure. So the screening of HCWs for latent tuberculosis infection (LTBI) is an important infection control measure. The skin test (e.g., TST), and the blood test (e.g., QuantiFERON®-TB Gold in tube, QFT-GIT…) are available for the diagnosis of LTBI. The specificity of the tuberculin skin test (TST) is low due to cross-reactivity of the purified protein derivatives (PPD) with the Bacille Calmette-Guérin (BCG) vaccine and with most nontuberculous mycobacteria (NTM). QFT-GIT is unaffected by previous BCG vaccination and most NTM. Aims: The purpose of this study is to understand the prevalent situation and risk factors for LTBI among HCWs in southern Taiwan using the QFT-GIT. Methods: A cross-sectional study was conducted from August 2010 to March 2011 among HCWs in the southern hospital. This study was approved by the Southern Hospital Ethics Committee. 180 HCWs enrolled were required to provide written informed consent. All participants underwent QFT-GIT and completed a questionnaire containing data on demography, medical history, subjective symptoms, life style, living environment, working conditions, medical work situation that provided information on possible risk factors for LTBI. Statistical analyses were performed using SAS software version 9.2. Results: 47 (26.11%) had a positive QFT-GIT. Living with others (OR=5.50, 95%CI=1.19-25.42), poor ventilation at home (OR=3.82, 95%CI=1.45-10.06), poor ventilation in the office (OR=2.34, 95%CI=1.01-5.44), and coffee consumption (OR=3.35, 95%CI=1.35-8.32) was associated with increased risk of a positive QFT-GIT in multivariate analysis. Conclusions: This study found that one fourth of HCWs had LTBI. Obviously, we should be concerned about the issue of M. tuberculosis infection at health care facilities for HCWs because there are some units with inadequate ventilation systems and infection control regulations, for example the TB unit. Inadequate ventilation at home, living with another person as well as drinking coffee are risk factors for LTBI. Therefore households should have adequate ventilations or have windows open whilst making sure family and roommates do not have TB. HCW who drink coffee should be aware of fatigue or staying up so late, adequate sleep is recommended.

碩士<br>國立臺灣師範大學<br>健康促進與衛生教育學系<br>106<br>Treatment of latent tuberculosis infection (LTBI) is an important strategy toward TB elimination. The study was to evaluate the completion rate of 3 months of isoniazide and rifapentine regimen (3HP) and compared to 9 months of isoniazid regimen (9H). A retrospective data base study was employed to analyze the treatment of LTBI data from 2016 Jan to 2017 Sep in Taipei city from Business Objects (BO) system of Taiwan Centers for Disease Control (Taiwan CDC). Using Cox proportional hazards regression to examine the correlation of cues to action, DOPT, barriers of action, and side effect to the completion rate for latent tuberculosis infection treatment. The total sample cases included in this study was 374, while 97.9% of the cases joined DOPT and had a completion rate of 89.8%. The 3HP regimens included 317 cases. 6.9% of them had side effects and the completion rate was 89.3%. The 9HP regimens had 56 cases. 1.8% of them had side effects and the completion rate was 92.8%. The completion rate for cases without side effects were significantly higher than those with side effects. Cases in 9HP regimens using telecare DOPT had 95% of completion rate while the regular DOPT hold a 89.3% completion rate. Age is the major predictor of completion rate. Completion rate decreases 5% for every one year increase of age. The 3HP regimens for DOPT with telecare is recomanded to elevate the acceptence of preventive treatment for LTBI.

博士<br>中山醫學大學<br>醫學研究所<br>104<br>SETTING: Treatment of latent tuberculosis infection (LTBI) is essential for eradicating tuberculosis (TB). Moreover, the patient adherence is crucial in determining the effectiveness of TB control. Isoniazid given by DOTS daily for 9 months (9H) is the standard treatment for LTBI in Taiwan. However, the completion rate is low due to the long treatment period and its side effects. The combined regimen using a high dose of rifapentine/isoniazid once weekly for 12 weeks (3HP) has been used as alternative treatment option for LTBI in United States. This may result in a higher completion rate. In this pilot study, patient adherence and cost of these 2 treatment regimens were investigated. OBJECTIVES: To assess the treatment completion rate and costs of 3HP and compare to those with 9H. METHODS: Data from 691 cases of LTBI treatments including 590 cases using the conventional regimen and 101 cases with rifapentine/Isoniazid were collected. The cost was the sum of the cost of treatment with Isoniazid for 9 months or with rifapentin /Isoniazid for 3 months of all contacts. The effectiveness was the cost of cases of tuberculosis avoided. RESULTS: In this study, the treatment completion rate for patients prescribed with the three months rifapentine/isoniazid regimen (97.03%) was higher than those given the conventional 9-month isoniazid regimen (87.29%) (p<0.001). The cost of 3HP and 9H was US$261.24 and US$717.3, respectively. The cost-effectiveness ratio with isoniazid for 9 months was US$ 15392/avoided one case of tuberculosis and US$ 5225/avoided one case of tuberculosis with 3HP. In addition, when compared with the conventional regimen, there were less patients discontinued with rifapentine/isoniazid regimen due to undesirable side effects. CONCLUSIONS: This was the first study to compare the 2 treatment regimens in Taiwan, and it showed that a short-term high-dosage rifapentine/isoniazid treatment regimen reduced costs and resulted in higher treatment completion than the standard LTBI isoniazid treatment.

碩士<br>長榮大學<br>醫學研究所<br>100<br>The outbreak of tuberculosis disease is still a serious problem in Taiwan, especially in some special closed settings, such as schools, prisons, hospitals, and military camps. Although there are some medical or public health units take the cautious monitors and tracing, the outbreak of tuberculosis have been reported continuously. Because of the long-term latent period and the X-ray, sputum smear and culture are just for the diagnosis of active TB mostly, excluding latent TB infection. Tuberculin Skin Test (TST) is the usual clinical tool for diagnosing latent TB infection in every country；however, TST results are prone to confounded by the Bacilli Calmette-Guerin (BCG) vaccination and the most of Nontuberculous mycobacterium. The Food and Drug Administration (FDA) in the United States has certified the usage of a third generation diagnostic method QuantiFERON-TB Gold In-Tube Test(QFT-GIT) in 2007, it doesn’t affected by BCG and NTM. The purpose of this study is to understand the prevalent situation and risk factors for LTBI among close contacts of the Local Community Hospital in Eastern Taiwan. Methods: This is a cross-sectional study and was approved by the Institutional Review Board. The subjects of this study were close contacts that had been exposed to the index patients with active TB. The study use questionnaires and anamnesis to investigate the risk factors about their demographics, previous history of TB, smoking status, and other factors for latent TB infection. This study was conducted from June to December 2011 in the community hospital located in the Eastern Taiwan , Additionally, this study followed up the seven index patients in Hualian Hospital and there were twenty-five household contacts accept the QFT-GIT test and Chest X ray and the questionnaires are analyzed by SAS ver. 9.2. Results: There were 115 patients held in this study . The first QFT-G test was conducted on June, with 47( 40.86%) positive. A second QFT-G test, a further three month later, with 34.78%(40/115)positive. And a third QFT-G test on December, with 34.78%(40/115) positive. The average rate of the QFT-GIT positive was 36.81% . The median age of the 115 patients was 55 years (range , 25-97). All of them had no any abnormal lesions on simple chest radiograph (CXR) but there were nine cases had the old TB history. In addition, the 47 positive cases were all show the sputum smear- negative. All of the participants, there were 86 person (75%) had BCG scars. All participants show the HIV negative. The Clustered infection (OR=3.659? 95%CI=1.178-11.367) was associated with the risk of QFT-GIT positive rate. Conclusion: This study showed that one third of the close contacts had positive QFT-GIT ,probably had latent tuberculosis infection. Evidently, the issue of M. tuberculosis infection at the closed institution is worth of concerning. Setting up the thorough infection control regulations and reporting system need the cooperation ,and also recommend the medical institution can establish the registration and management interface for monitoring the close contacts of TB patients

碩士<br>國立中興大學<br>生物醫學研究所<br>98<br>Rheumatoid arthritis (RA), a chronic inflammatory articular disease, is characterized by infiltration of T cells with the joint, and bone erosions. Proinflammatory cytokines released from immune cells play an important role in the destruction of joints in RA. It was thought to be a predominance of type 1 helper T (Th1) cells-mediated disease. Recently, a critical role of the interleukin (IL)-23/IL-17 axis in the progression to chronic destructive arthritis has been demonstrated. Previous studies suggest a possible role of Mycobacterium tuberculosis (Mtb) in the pathogenesis of RA. Recent reports also show that Mtb antigens have been detected in synovial fluid of patients with RA. It has also been demonstrated that Th17 cells could be induced by Mtb infection and may contribute to Mtb-mediated inflammation. The aim of this study was to investigate the association of patients of Th cells with RA and latent Mtb infection (LTBI). Tuberculin skin test (TST) was performed using Mantoux method and QuantiFERON-TB Gold (QFT) assay was performed by measuring interferon-gamma (IFN-γ) levels in whole blood samples treated with TB-specific antigens. LTBI was defined according to TST and QFT results. The frequencies of circulating Th1, Th2 and Th17 cells were quantified using three-color flow cytometry analysis, and serum levels of Th17- related cytokines were measured using ELISA. In this study, significantly higher frequencies of Th1, Th17, and tumor necrosis factor-α (TNF-α) producing CD4 T cells were observed in RA patients with LTBI (median = 0.58%, IQR 0.17%-1.63%; median = 0.05%, IQR 0.0 %-0.25%; median = 2.31%, IQR 0.42%-7.30%; respectively) than those without LTBI (median = 0.26%, IQR 0.07%-0.57%; median = 0.03%, IQR 0.00%-0.06%; median = 0.17%, IQR 0.04%-1.60%, respectively; all p &amp;lt;0.05) before anti-TNF-α therapy. Significantly higher levels (pg/ml) of serum IL-6, IL-1β, IL-23,IL-21, IL-22, TNF-α and IFN-γ were observed in RA patients with LTBI than in those without LTBI. There were no significantly differences in levels of serum IL-17 between RA patients with and without LTBI. In conclusion, our results showed that the levels of circulating Th1 and Th17 cells, and serum levels of Th17-related cytokines were significantly higher in RA patients with LTBI than in those without LTBI, suggesting these cytokines might play a role in the pathogenesis of LTBI in RA patients before anti-TNF-α therapy.

碩士<br>高雄醫學大學<br>醫學研究所碩士班<br>106<br>Background The treatment of latent tuberculosis infection (LTBI) is one of the important strategies to eradicate tuberculosis infection. Patients with hemodialysis are in high risk of LTBI. Vitamin D deficiency is related to the incidence of LTBI and it is also common in dialysis population. Therefore, we conducted a study to explore the risk factors of LTBI in a hemodialysis population and to clarify the relationship between vitamin D status, vitamin D supplementation, and LTBI. Materials and methods We conducted two studies. First, a cross-sectional study was conducted in Kaohsiung Medical University Hospital from Mar to May 2017. A total of 290 hemodialysis patients were enrolled for analysis. The baseline characteristics, comorbidities, laboratory data, including QuantiFERON-TB Gold in-tube test (IGRA), and serum vitamin D concentrations were included in this study. Second, hemodialysis patients with LTBI receiving regimen of weekly rifapentine plus isoniazid for 3 months (3HP) were enrolled for analysis. Laboratory data and adverse events (AEs) were collected for evaluation. Results The prevalence of positive-IGRA was 25.2% (73/290). Multivariate analysis revealed that male, age older than 65 years old, and previous tuberculosis history were associated with positive-IGRA. There was no association between vitamin D deficiency, vitamin D supplementation and IGRA results. Further subgroup analysis adjusted by diabetes, glycosylated hemoglobin level, age, gender, dialysis duration, cancer and vitamin D supplementation, the results were consistent. Twenty-six patients with LTBI were treated with 3HP, 17 patients completed treatment, 9 patients were interrupted due to AEs, and the treatment completion rate was 65.4%. Nineteen patients had more than one AE. Fatigue, fever, and gastrointestinal discomfort were the most common AEs. No patients developed hepatotoxicity or death during the 3HP treatment period. The proportion of vomiting was higher in patients who discontinued the treatment (p = 0.034). Conclusion We found a moderate to high prevalence of LTBI in the southern Taiwanese dialysis center. The risk factors of positive-IGRA were male, age, and tuberculosis history. Vitamin D deficiency and low-dose vitamin D supplementation were not related to the IGRA results. In addition, 26 dialysis patients received 3HP treatment, 17 patients completed treatment courses. 3HP completion rate was 65.4%, and the incidence of AEs was high.

Submitted in fulfillment of the requirements for the degree of Master’s of Technology: Radiography, Durban University of Technology, Durban, South Africa, 2015.<br>Introduction Tuberculosis remains a leading cause of death, second to the Human Immunodeficiency Virus. The risk of latent tuberculosis infection and active tuberculosis disease is a known occupational hazard. In South Africa, a high tuberculosis burden country, the potential of Mycobacterium tuberculosis transmission to health care workers is high. This includes diagnostic radiographers and other radiology staff working in radiology departments. Purpose of the Study This study aimed to investigate the association of demographic and occupational factors with latent tuberculosis infection in radiology staff in public sector hospitals of the eThekwini Health District. Methodology This cross-sectional study was conducted from 26 February 2013 to 07 June 2013. Quantitative methods were used to test for associations of demographic and occupational factors with latent tuberculosis infection in participants. A sample size of 181 participants for an estimated population of 340 radiology staff was recommended at the proposal stage. The study consisted of two phases; the questionnaire survey (phase one) and the administration of a two-step tuberculin skin test (phase two). Data was obtained with regard to demographics, occupational history, social behaviours, medical history; and family and home histories. Demographic and occupational associations with latent tuberculosis infection were made in relation to the size of the first tuberculin skin test induration. Frequency distributions were developed to describe data categories. Pearson’s and Spearman rho’ correlation coefficients were used to test for correlations between the independent variables. The chi-square test was used to determine associations between the categorical independent variables and the dependent variable. Bivariate analyses were performed using these tests. The multivariate analysis was performed using logistic and linear regression on the dependent variable. Results A total of 182 questionnaires were returned from approximately 280 radiology staff. At the outset, all doctors working in the radiology department had to be excluded due to numerous failed attempts to enlist their participation. Fifty-three (29.12 percent) participants were excluded from phase one of the study and a further thirteen participants were excluded from phase two. The total sample was 116 participants. Of the 116 participants, 86.2 percent tested positive for latent tuberculosis infection at the first step of the two-step testing method used. One (0.86 percent) participant went on to convert at the second step, testing positive at this level. Demographic associations with latent tuberculosis infection included age (older) as an associated factor. A significant demographic association with latent tuberculosis infection was the use of alcohol (p-value 0.033 on the multivariate analysis). Occupational associations with latent tuberculosis infection included longer durations of employment. The annual income (higher income earners) displayed significant associations with latent tuberculosis infection (p-value 0.048 on the multivariate analysis). It is necessary in this study to note that participants include support personnel (lower income earners) making up 37.8 percent of the study, diagnostic radiographers making up 48.3 percent; and radiography managers/assistant managers (highest income earners) making up 13.8 percent of the study. Conclusion and recommendations The risk of transmission of Mycobacterium Tuberculosis to health care workers is a known occupational hazard. This study has described the prevalence of latent tuberculosis infection in radiology staff, at district and regional hospitals within the eThekwini Health District. With 23.62 percent of all participants already having active TB disease and 86.2 percent of the tested group displaying positive results for latent tuberculosis infection, using the tuberculin skin tests, the need for tuberculosis screening is essential. The findings of this study will be used as a health improvement mechanism for stakeholders, having identified potential gaps in medical screening in healthcare in Kwa-Zulu Natal. This study makes recommendations for the early detection of active tuberculosis infection and the monitoring of health care workers that are latently infected, thus assisting in reducing the rate of conversion of latent tuberculosis infection to active tuberculosis disease in radiology staff. This reduces long-term exorbitant costs related to health care associated infections, such as tuberculosis. It also reduces rates of transmission and cross infection to both co-workers and already immunocompromised patients, helping to curb the overall epidemic in South Africa.

碩士<br>國立臺灣大學<br>流行病學研究所<br>89<br>Background: The complicated disease natural history of tuberculosis in relation to tuberculosis skin test (TST) with the treatment of latent tuberculosis infection (LTBI) given the high coverage rate of BCG vaccination has not been fully addressed. Objective: The aims of this study are to assess the relative contributions of exogenous disease due to re-infection and endogenous and to perform a cost-effectiveness analysis for the use of TST plus LTBI by different screening regimes given the current BCG vaccination in the general population and in the high-risk group. Methods: A computer simulation model using the Markov model was proposed to model the disease natural history of TB. Markov cycle tree and Monte Carol simulation were employed to assess the relative contributions of exogenous disease, re-infection and endogenous reactivation. Cost-effectiveness analysis was performed to calculate the incremental cost-effectiveness ratio for averting TB cases and deaths by different screening regimes starting from 20, 30, 40, 50, and 60 years of age. Results: The incremental cost-effectiveness ratios to achieve an additional life-year in the screening regimes starting from 20, 30, 40, 50 and 60 years of age against no screening are calculated as $6410, $4072, $2858, $3863 and $13416, respectively, for the general population and $2183, $1506, $1126, $1567and $4913, respectively, for the high-risk group. The sensitivity analysis shows if the effectiveness of INH is dropped to 30% TST screening is no longer cost-effective. Conclusion: the present study develops a computer simulation model for elucidating the disease natural history of TB and cost-effectiveness analysis for TST with the treatment of LTBI. The results suggest that TST screening regime may be the most cost-effective at the start of 40 years of age for the selected high-risk group.

Vaccination is one of the most successful public health interventions in history, and is estimated to save lives of 3 million children globally each year. Ongoing surveillance is warranted to identify further evolution of the epidemiology of vaccine preventable diseases, and to evaluate the effects of vaccines provided. This dissertation aims to explore the impact of vaccines on disease burden, and effectiveness of diagnostic tools for two important infectious diseases; pneumonia and tuberculosis (TB). The first study employed a large electronic health record data, Massachusetts Health Disparities Repository (MHDR), to evaluate impact of 13-valent conjugated pneumococcal vaccine (PCV13) on all-cause pneumonia among children who receive primary care at Boston Medical Center (BMC). We extracted all-cause pneumonia cases diagnosed at both inpatient and outpatient settings among children younger than 8 years of age. Using interrupted time-series regression analysis monthly rates estimated for years after (2011–2013) implementation of PCV13 were compared to expected rates calculated from pre-PCV13 era (2007–2009). The year of PCV13 introduction (2010) was excluded. We also extracted cases of urinary tract infection and evaluated as control outcome. At the end of 2013 compared to prePCV13 era, among children younger than 2 years of age there was a 35.3% (95% CI 5.4–65.3) reduction in all-cause pneumonia cases. In children with comorbidity, pneumonia declined by 38.8% (95% CI 11.1 to 65.4) in those younger than 2 years of age, and 28.7% (95% CI 2.9 to 54.5) in those 2 to 8 years of age. The results of this study contribute to the growing body of evidence supporting the benefit of indirect protection with conjugated vaccines, and emphasize the importance of high sustainable vaccine coverage rates. The second and the third studies used data from the Tuberculosis Epidemiologic Studies Consortium (TBESC) Study-1, a 10-site collaboration of academic institutions and state and local TB control programs that is funded and administered by the Division of Tuberculosis Elimination at the Centers for Disease Control and Prevention (CDC). The second study evaluated the impact of Bacille Calmette Guérin (BCG) vaccination, which continues to be the only vaccine available for prevention of TB, on tuberculin skin testing (TST) results. Using the data collected TBESC Study-1 between September 2012 and September 2014, we examined the association between BCG vaccination and TST positivity. Logistic regression models were used to calculate adjusted prevalence ratios (PR) and 95% confidence intervals (CI). Prior BCG vaccination had no impact on the TST results once adjusted for history of household contacts (adjusted PR 1.0, 95% CI 0.4–1.5). The results of this study add further evidence that BCG vaccination has little impact on TST results in children, particularly in older age groups. The third study examined the cost-effectiveness of three different screening strategies compared to no screening for latent tuberculosis infection (LTBI) in a population with high proportion of foreign-born individuals who have different risk levels for developing TB. In this study, everyone was tested with using all available tools for LTBI: TST, and interferon-gamma release assays (IGRAs) during their enrollment visit. We used decision tree analysis and Markov models to compare TST only, IGRA only, TST followed by IGRA among those who were TST positive, and no screening strategies. Regardless of the assumptions and tests used, screening provided better health outcomes such as less TB cases and less TB related mortality compared to no screening. The incremental cost-effectiveness ratio (ICER) of TST followed by IGRA compared to no screening was $75,094 per QALY gained. The results of this study suggest that prioritizing certain groups for targeted LTBI screening such as foreign-born individuals, and using TST followed by IGRA can maximize the impact of public health resources allocated to eradicate TB in the U.S. The findings from these studies will contribute to the further understanding of the impact of the vaccines and the changing epidemiology of vaccine-preventable diseases providing more insight to formulate new strategies to improve overall health of children.