Dissertations / Theses on the topic 'Tuberculosis in bovine species'

The eco-epidemiology of bovine tuberculosis (Tb) in wild deer (mainly red deer Cervus elaphus) in New Zealand was investigated. Bovine Tb is caused by Mycobacterium bovis. Specific aims were to clarify the likely routes of infection in deer, and to determine the status of deer as hosts of Tb, the likely rates and routes of inter- and intra-species transmission between deer and other wildlife hosts, the role of deer in spreading Tb, and the likely utility of deer as sentinels of Tb presence in wildlife. As the possum (Trichosurus vulpecula) is the main wildlife host of Tb, the research also included some investigation of transmission routes in possums. Patterns of infection were measured in 994 deer killed between 1993 and 2003. Tb prevalence varied between areas (range 8–36%). Few deer had generalised infection, with 21–68% of infected deer having no visible lesions, depending on the area. The retropharyngeal lymph nodes and oropharyngeal tonsils were commonly infected. No dependent fawns less than 0.75 years old were infected, indicating intra-species transmission is rare in wild deer. Where possums were not controlled, the net (cumulative) force of infection in young (1–4 y) deer was 0.10–0.24 per year in males and 0.09–0.12 per year in females, but much lower in older deer (less than 0.05 per year). Possum control reduced the net force of infection quickly, and eventually to zero. However, Tb persisted in possum-controlled areas through immigration of infected deer and, for almost a decade, through the survival of resident deer infected before possum control. Tb was lost from infected deer at an exponential rate of 0.13 per year, mostly as a result of deer recovering from infection rather than dying from it. Wild deer do die of Tb, but there was no discernible effect on age structure. The occurrence of infection in deer was not linked to the local deer or possum density at their kill sites (i.e. in their home range), but the area-wide prevalence of Tb in deer was closely correlated with Tb levels in possums, which were in turn correlated with area-wide measures of possum density. For wild deer in New Zealand, Tb is a persistent but usually inconsequential disease of the lymphatic system. It is acquired mainly by young independent deer, usually orally via the tonsils, and probably as a result of licking infected possums. Many species fed on deer carrion, including possums. Most possums encountering carrion did not feed on it, but a few fed for long periods. Other scavengers such ferrets (Mustela furo), hawks (Circus approximans), and weka (a hen-sized flightless native bird; Gallirallus australis) fed in a way that probably increased the infectivity of carrion to possums. Commercial deer hunting may have facilitated the historical establishment of Tb in possums. Scavenging (including cannibalism) and interactions with dead and dying possums are identified for the first time as potentially important routes for transmission of Tb to possums, and I develop new hypotheses involving peri- and post-mortem transmission in possums that explain many of the epidemiological patterns that are characteristic of the disease in possum. In continuous native forest, deer home range size averaged 250 hectares for six young females, and over twice that for two males. Over 90% of infected deer are likely to die within 2 km (females) or 6 km (males) of where they acquired Tb, but deer could occasionally carry Tb up to 30 km. Deer will be useful as sentinels, but only where other sentinels are rare, because the force of infection for a deer with a single infected possum in its home range is only 0.004 per year, compared to greater than 0.2 per year for deliberately released pigs. Deer are occasionally capable of initiating new cycles of infection in wildlife, but deer control is not essential to eradicate Tb from wildlife.

A study on molecular epidemiology of bovine tuberculosis in man and cattle in Tanzania was carried out with two components. The first component was based on field investigation of tuberculosis in cattle and man in Arusha region, in the north and in the Usangu Plains in the Southern Highlands of Tanzania. The second component involved laboratory analysis of strains acquired from field study by both conventional and molecular biology techniques. The IS986 and mtp40 multiplex PCR developed in the course of this study was able to different M. bovis from M. tuberculosis. DNA fingerprinting of all the strains cultured was carried out using restriction fragment length polymorphism (RFLP) and spoligotyping techniques. Strains of M. bovis from man from Arusha gave similar DNA fingerprints to those from cattle, while the human M. bovis, strains from other places gave different fingerprints from those from cattle. M. tuberculosis strains were found to belong to three clusters, with one cluster containing over 60% of the strains. Intersegment PCR, a molecular typing technique developed in the current study was able to differentiate strains but the results were influenced by the concentration of template DNA. A fragment of RAPD PCR found only in M. bovis and absent in M. tuberculosis and other atypical mycobacteria was cloned and sequenced. The DNA sequence of the cloned fragment was found to match a M. tuberculosis cosmid, which also matched rfbE gene of Yersinia enterocolitica. Specificity testing revealed hybridization to M. tuberculosis as well. The findings of the above studies have shown the existence of M. bovis infection in man and cattle in Tanzania. The study has also shown the zoonotic importance of infection in the two populations which necessitates a veterinary/medical approach to the control of the disease in Tanzania. Furthermore, it has been shown that molecular biology techniques are better epidemiological tools in studies of zoonotic conditions such as tuberculosis. The study was unable to find a specific DNA element for M. bovis. This observation concurs with others which have found 100% homogeneity between species of the M. tuberculosis complex.

Bovine tuberculosis (BTB) is a zoonotic disease that affects domestic and wild animals, and humans. It is caused by Mycobacterium bovis (M. bovis) and has a wide host range. The effective control of BTB is of paramount importance and this can be achieved through the use of accurate and comprehensive diagnostic tests. The most widely used methods to detect BTB are the skin test and in vitro gamma interferon assay which do not detect anergic animals, but serological tests such as ELISA and fluorescence polarization assay (FPA) have been found promising in ancilliary tuberculosis diagnosis. The overall aim was to study M. tuberculosis complex (MTBC) protein, mycobacterial protein bovis 70 (MPB70) as a target for serological assays in the detection of antibodies to bovine tuberculosis. The MPB70 protein was expressed, purified and labeled with fluorescein (FITC). The mpb70 gene was fragmented into three regions without disrupting predicted epitopes. The resulting protein Fragments were expressed as fusion proteins with the monster green fluorescent protein (MGFP). The recombinant MPB70 (rMPB70) and the expressed gene fragments 2&3 were tested in immunoblots and ELISAs. The rMPB70 and fragment 2-MGFP reacted with chicken antibodies raised against rMPB70 and immune sera from BTB infected buffaloes. MPB70 peptides were synthesized as an approach to identify even smaller antigenic regions. The peptides BT1G (residues 31-45) and BT51L (residues 81-95) were recognised by anti-MPB70 chicken antibodies in the ELISA and fall within fragment 1 and 2, respectively. The tracers (rMPB70-FITC, fragment 2-MGFP fusion and peptides BT1G&BT51L) were tested in the FPA, but the results failed to distinguish between immune sera from chickens immunized with rMPB70 and negative control sera. Even though the FPA was not successful, the MPB70 fragment 2-MGFP fusion protein, which was recognized by sera from BTB infected buffaloes, was tested in an ELISA using panels of sera from uninfected and naturally M. bovis infected buffaloes and cattle. The diagnostic performance of the ELISA was, however, overall unsatisfactory and hence of very limited use as a serological test to detect antibody responses to BTB as a stand-alone assay. Sera from some of the animals gave false positive reactions indicating that MPB70 was not sufficiently specific for serodiagnosis of M. tuberculosis complex infections.
Dissertation (MSc)--University of Pretoria, 2012.
Veterinary Tropical Diseases
unrestricted

Bovine Tuberculosis (bTB) is a disease of significant economic importance, being one of the most persistent animal health problems in the UK and the Republic of Ireland and increasingly constituting a public health concern especially for the developing world. Limitations of the currently available diagnostic and control methods, along with our incomplete understanding of bTB transmission, prevent successful eradication. This Thesis addresses the development of a complementary control strategy which will be based on animal genetics and will allow us to identify animals genetically predisposed to be more resistant to disease. Specifically, the aim of my PhD project is to investigate the genetic architecture of resistance to bTB and demonstrate the feasibility of whole genome prediction for the control of bTB in cattle. Genomic selection for disease resistance in livestock populations will assist with the reduction of the in herd-level incidence and the severity of potential outbreaks. The first objective was to explore the estimation of breeding values for bTB resistance in UK dairy cattle, and test these genomic predictions for situations when disease phenotypes are not available on selection candidates. Through using dense SNP chip data the results of Chapter 2 demonstrate that genomic selection for bTB resistance is feasible (h2 = 0.23(SE = 0.06)) and bTB resistance can be predicted using genetic markers with an estimate of prediction accuracy of r(g, ĝ) = 0.33 in this data. It was shown that genotypes help to predict disease state (AUC ≈ 0.58) and animals lacking bTB phenotypes can be selected based on their genotypes. In Chapter 3, a novel approach is presented to identify loci displaying heterozygote (dis)advantage associated with resistance to M. bovis, hypothesising underlying non-additive genetic variation, and these results are compared with those obtained from standard genome scans. A marker was identified suggesting an association between locus heterozygosity and increased susceptibility to bTB i.e. a heterozygote disadvantage, with the heterozygotes being significantly more in the cases than in the controls (x2 = 11.50, p < 0.001). Secondly, this thesis focused on conducting a meta-analysis on two dairy cattle populations with bTB phenotypes and SNP chip genotypes, identifying genomic regions underlying bTB resistance and testing genomic predictions by means of cross-validation. In Chapter 4, exploration of the genetic architecture of the trait revealed that bTB resistance is a moderately polygenic, complex trait with clusters of causal variants spread across a few major chromosomes collectively controlling the trait. A region was identified on chromosome 6, putatively associated with bTB resistance and this chromosome as a whole was shown to contribute a major proportion (hc 2= 0.051) of the observed variation in this dataset. Genomic prediction for bTB was shown to be feasible even when only distantly related populations are combined (r(g,ĝ)=0.33 (SE = 0.05)), with the chromosomal heritability results suggesting that the accuracy arises from the SNPs capturing linkage disequilibrium between markers and QTL, as well as additive relationships between animals (~80% of estimated genomic h2 is due to relatedness). To extend the analysis, in Chapter 5, high density genotypes were inferred by means of genotype imputation, anticipating that these analyses will allow the identification of genomic regions associated with bTB resistance more closely, and that would increase the prediction accuracy. Genotype imputation was successful, however, using all imputed genotypes added little information. The limiting factor was found to be the number of animals and the trait definitions rather than the density of genotypes. Thirdly, a quantitative genetic analysis of actual Single Intradermal Comparative Cervical Test (SICCT) values collected during bTB herd testing was conducted aiming to investigate if selection for bTB resistance is likely to have an impact on the SICCT diagnostic test. This analysis demonstrated that the SICCT has a negligibly low heritability (h2=0.0104 (SE = 0.0032)) and any effect on the responsiveness to the test is likely to be small. In conclusion, breeding for disease resistance in livestock is feasible and we can predict the risk of bTB in cattle using genomic information. Further, putative QTLs associated with bTB resistance were identified, and exploration of the genetic architecture of bTB resistance revealed a moderately polygenic trait. These results suggest that given that larger datasets with more phenotyped and genotyped animals will be available, we can breed for bTB resistance and implement the genomic selection technology in breeding programmes aiming to improve the disease status and overall health of the livestock population. Using the genomics this can be continued as the epidemic declines.

Bovine tuberculosis (bTB) is one of the most complex, persistent and controversial problems facing the British cattle industry. It is also potentially zoonotic and so has public health implications. The incidence of the disease has been increasing in Great Britain for more than 20 years and is now endemic in southwest regions of the country and occurs sporadically elsewhere. Scotland records very few incidences of bTB and was declared as an Officially bTB free (OTF) region in 2009 for the purposes of cattle trading. However, in order to retain its OTF status Scotland must continue to demonstrate the ability to report low level of disease prevalence whilst maintaining its vigilance to potential new outbreaks. This thesis uses a variety of epidemiological and statistical models to evaluate the ongoing control strategies for bTB in Scottish cattle herds and highlight potential limitations to the current surveillance programmes. In the absence of an established wildlife reservoir, livestock movements are considered the primary mechanism for introduction of bTB into cattle herds. I use movement and bTB data to estimate the within-herd incidence rate for each infected farm in Scotland. The results suggest that this rate varies across farms, and is dependent on the herd size and length of disease exposure. These incidence rates are then used to parameterise a multi-herd dynamic model using stochastic simulations that incorporate multiple disease transmission pathways. With this approach I evaluate the impact of different routine test protocols on the overall simulated epidemics. Based on the model outcome, abattoir surveillance alone is not sufficient to maintain infection at a low constant level. Whilst adapting to more frequent routine testing regime can reduce disease incidence, the sensitivity of the surveillance methods can also have a big impact on the long term stability of the disease prevalence and can act as the main barrier to eradicating the disease from low incidence regions. The single intra-dermal comparative cervical tuberculin (SICCT) test used in the current routine herd surveillance relies on stimulating an immune response and observing delayed hypersensitivity reactions in infected animals. The test suffers highly variable, and often poor, sensitivity with current estimates ranging from 50% to 80%. The lower sensitivities may be associated with early stages of infection, concurrent illness, and farm management conditions as well as the presence of sub-clinically infected carriers that can potentially escape detection. In addition, there was evidence that physiological stress can have a marked effect on the immune responses in animals affected with bTB. I conducted two different types of case-control analyses to investigate the potential effect of stress related events on the outcome of the SICCT test. In the first analysis, a matched design is implemented to examine the effect of recent calving on reactivity to the SICCT. SICCT test positive cattle (cases) were matched with test negative (control) animals within the same farm. By selecting herd-mates (i.e. animals within the same herd at the same time), the study aims to control for space and time. Furthermore, animal age and breed were used as additional selection criteria to control for previous exposure period and potential genetic variation to the reaction of SICCT test outcome. Results from a conditional logistic regression model indicated that animals calved within 60 days prior to test were less likely to respond to the SICCT test in comparison to non-recently calved animals, and that this effect was strongest in the first 2 weeks of the post-partum period. In the second analysis, animals identified with gross pathology at post-mortem (TB-like lesion and/or bacteria culture) and that were SICCT test negative within 60 days prior to slaughter (representing false negative) were compared with confirmed test positives (true positives). Results from multivariable logistic regression model suggested that the probability of missed infection by SICCT test increases with age and male cattle have higher odds of being a false negative compared to females. Repeated skin tests within 60 and 120 days, as well as recent movement and parturition, were all statistically associated with false negative test outcome. Under future surveillance systems, these results could be used to adjust the timings of testing relative to calving, movements and previous test occasions in order to minimise the risks of false negative test results. Alternatively, increasing the threshold for reactor definition in animals under these categories could be considered to complement the poor test sensitivity.

The aim of the study was to gain knowledge on molecular techniques (spoligotyping and VNTR typing) in analysis of the Mycobacterium tuberculosis complex and characterize M. bovis isolates available in Swaziland.
Dissertation (MSc)--University of Pretoria, 2012.
Veterinary Tropical Diseases
MSc
Unrestricted

This thesis covers the formulation and analysis of a number of deterministic, continuous models of infection by a disease such as bovine tuberculosis in one species (essentially badgers) and in two mutually infective species (badgers and cattle). We examine the dynamics of the disease in each model and then consider the effects of the application of different badger culling strategies which have the objective of eliminating the disease in cattle.

Bovine tuberculosis (bTB) is an important zoonosis, with considerable health, economic and conservation impacts across Europe. The disease shows considerable heterogeneity on both a national and international scale, with a more severe problem occurring in the Western and Southern European countries. This pattern of disease is considered to be due primarily to the role played by bTB-infected wildlife in the dynamics ofthe disease. In the first part of this thesis, a spatial stochastic simulation model is used to examine the dynamics and control of bTB infection in one of the major wildlife host species, the badger (Meles meles).The results indicate that infection can persist at the badger group sizes frequently found within the British Isles. Moreover, the presence of external sources of infection alters the disease dynamics by lowering the threshold of infection. Vaccination of badgers could be an effective method of bTB control. However, it would need to be deployed over a long period of time and the presence of external sources of infection may seriously compromise its effectiveness. In the second part of the thesis, a statistical model is developed to quantify existing and potential hazards of bTB posed by combined livestock-wildlife host communities across Europe. Current hazards are dominated by the contribution of cattle (Bas taurus). However, wildlife species, especially roe deer (Caprealus eaprealus) and wild boar (Sus serafa), have the potential to assume a greater role in disease dynamics in the future. The results of the thesis demonstrate the potential significance of multiple host communities in bTB dynamics at a range of scales. A better understanding of the dynamics of bTB in mixed livestock-wildlife communities with multiple hosts is essential to underpin the development of more effective bTB control strategies across Europe.

In this work peptide antigens [ESAT-6,p45 in water (1ml, 1mg/ml)] have been adsorbed onto 10mg inorganic substrates (hydroxyapatite (MHA P201;P120, CHA), polystyrene, calcium carbonate and glass microspheres) and in vitro release characteristics were determined. The aim of formulation was to enhance the interaction of peptides with antigen presenting cells and to achieve rapid peptide release from the carrier compartment system in a mildly acidic environment. Hydroxyapatite microparticle P201 has a greater surface area and thus has the largest peptide adsorption compared to the P120. CHA gave a further higher adsorption due to larger surface area than that available on microparticles. These particles were incorporated into the BOVIGAMTM assay to determine if they improve the sensitivity. After overnight incubation the blood plasma was removed and the amount of IFN-g in each plasma sample was estimated. CHA and MHA P201 gave a significantly higher immune response at low peptide concentration compared to the free peptide, thus indicating that these systems can be used to evaluate Tuberculosis (TB) amongst cattle using the BOVIGAMTM assay. Badgers are a source of TB and pass infection to cattle. At the moment vaccination against TB in badgers is via the parenteral route and requires a trained veterinary surgeon as well as catching the badgers. This process is expensive and time consuming; consequently an oral delivery system for delivery of BCG vaccines is easier and cheaper. The initial stage involved addition of various surfactants and suspending agents to disperse BCG and the second stage involved testing for BCG viability. Various copolymers of Eudragit were used as enteric coating systems to protect BCG against the acidic environment of the stomach (SGF, 0.1M HCl pH 1.2 at 37oC) while dissolving completely in the alkaline environment of the small intestine (SIF, IM PBS solution pH 7.4 at 37oC). Eudragit L100 dispersed in 2ml PBS solution and 0.9ml Tween 80 (0.1%w/v) gave the best results remaining intact in SGF loosing only approximately 10-15% of the initial weight and dissolving completely within 3 hours. BCG was incorporated within the matrix formulation adjusted to pH 7 at the initial formulation stage containing PBS solution and Tween 80. It gave viability of x106 cfu/ml at initial formulation stage, freezing and freeze-drying stages. After this stage the matrix was compressed at 4 tons for 3 mins and placed in SGF for 2 hours and then in SIF until dissolved. The BCG viability dropped to x106 cfu/ml. There is potential to develop it further for oral delivery of BCG vaccine.

Bovine tuberculosis (TB) is arguably the most important animal health problem in the world. TB is endemic in the Global South, and also affects several nations and regions with highly developed cattle farming industries and statutory eradication programmes in the European Union, including Northern Ireland. The disease has implications for livestock agriculture, wildlife ecology, public health, and the national economy. In addition to scientific and technical complexities, socio-economic and socio-cultural factors affect efforts to control the disease. Disease problems such as TB at the human-nature interface are complex and indeterminate, and require innovative multidisciplinary research to find holistic and workable solutions: geography has much to contribute. This investigation uses a political ecology framework, and provides explanations for the historical and geographical patterns of the disease through a ‘chain of explanation’ approach (Blaikie & Brookfield, 1987). It utilizes political ecology, STS, rural, cultural, health, ‘more-than-human’ and veterinary literatures to produce a political ecology of animal disease control in the First World. Significantly, this account is as much about people and politics as it is about land use, technology, cattle, badgers, bacteria and disease. Conducted from the positionality of being a vet and a farmer’s son, and based on ethnographic interviews with farmers, vets, policy makers and other agricultural industry representatives, the links in the chain explain why the statutory eradication programme has not yet been successful in achieving its original aim. The disease continues to spread across the landscape and evades efforts to eradicate. The thesis shows how TB permeates time and space shaped by global economic forces, political structures, cultural practices and complex ecologies. TB, often invisible and underestimated, must be made visible again. New network structures are required to rescale governance and move closer to the target of TB eradication.

M. bovis is a zoonosis and is the aetiological agent of bovine TB. The incidence of bovine TB in the UK is increasing, demonstrating that the current test and slaughter policy is failing. M. bovis-BCG, the vaccine used against human TB, is not used in cattle as it interferes with the tuberculin skin test and only confers partial protection. The control of bovine TB will require the design of a more efficacious vaccine and discriminatory diagnostic test. To achieve this, a greater understanding of both the immune response induced by the mycobacteria and the protective immune response required to clear or control M. bovis infection in cattle is needed. In human and mouse studies, CD8+ T cells have been proposed to play an important role in immunity to mycobacteria. The aim of this study was to identify and define the CD8+ T cells induced by BCG vaccination and/or M. bovis infection in cattle. Initial experiments identified different subsets of CD8+ T cells present in cattle using expression of surface and effector molecules. The CD8+ population is heterogeneous and contains ap (TCR1"CD3+), y8 (TCR1+CD3+) and NK (TCRTCD3") cells. CD8+ cells could be divided into CD8hiCD3+ and CD8loCD3+/ The (CD8hiTCRT) ap+ T cells were analysed in this study as these form part of the adaptive immune response. Age-related increases in the percentage of activated/memory CD8hlTCRl" T cells were observed in blood as shown by increases in expression of the activation marker CD25 and memory marker CD45RO. Concomitant decreases were observed in the percentage of CD8hiTCRlT cells that express CD45RA, CD62L and CD27, surface molecules associated with naive T cells. The percentage of CD8hiTCRl" T cells in blood expressing perforin and IFN-gamma also increased with age. The CD8hlTCRlT cells present in the BAL were mainly activated/memory T cells as shown by a combination of expression of surface and effector molecules. In contrast, the CD8hlTCRlT cells present in the lymph nodes more resembled naive T cells with only a small percentage expressing perforin and IFN-gamma. A minor population of CD8hiTCRl"CD45RO+CD62L+ T cells were present in the LN which may be the bovine equivalent of murine central memory cells. BCG vaccination of cattle induces mycobacteria-reactive CD8hlTCRl"CD45RO+ T cells. These cells mediated recall responses to BCG, detected by proliferation, production of IFN-gamma, up-regulation of perforin expression and lysis of BCG-infected hi + macrophages (M). M. bovis reactive-CD8mTCRl"CD45RO T cells were detected in non-vaccinated and BCG-vaccinated animals after infection with M. bovis. These cells proliferated and produced IFN-gamma in response to M. bovis-infected but not BCG-infected M( ), indicating that they were responding to an M. bovis-specific antigen. Post- challenge responses in the CD8hiTCRl'CD45RO+ T cells from BCG-vaccinees were considerably greater than those of non-vaccinated animals. M 6ov/s-reactive CD8hiTCRl"CD45RO+ T cells reduced mycobacterial viability when cultured with BCG- or M. bovis-infected M( >. CD8hiTCRl"CD45RO+ T cells present in the lungs of M. bovis-infected animals expressed IFN-gamma after culture with mycobacteria. These results demonstrate that mycobacteria-reactive CD8hiTCRl"CD45RO+ T cells that express effector functions are present at the site of infection, and may contribute to the control of M. bovis infection in cattle. This study provides a basis to investigate the role of CD8hiTCRl"CD45RO+ T cells in immunity to M. bovis infection in cattle and to evaluate the effectiveness of new TB vaccines at inducing CD8+ T cell responses.

El objetivo de la presente tesis ha sido obtener información sobre la epidemiología de la Tuberculosis Bovina (TBb) en rebaños vacunos así como la obtención de datos para la implementación de un posible sistema de vigilancia basado en riesgo. En el primer estudio se analizó la variación espacio-temporal del riesgo de TBb en rebaños vacunos desde el año 2006 hasta el 2011. Los resultados indicaron que la prevalencia y la incidencia fueron más elevadas en algunas comarcas y en algunos años, comparando con la evolución global a nivel de país. El análisis de potenciales factores de riesgo indicaron que tanto los movimientos entre granjas provenientes de zonas de elevada incidencia (>1%) como la presencia de ganado de lidia, incrementaban el riesgo de infección. En el segundo estudio se describió una aproximación a un sistema de vigilancia basado en riesgo que se está evaluando actualmente en Nueva Zelanda. Dado que la presencia de TBb en granjas está conducida por un número de factores que incluyen: historial de infección previo en la explotación, frecuencia de test diagnósticos llevados a cabo en la explotación, localización geográfica y los movimientos de animales; el objetivo del estudio fue calcular una puntuación de riesgo de infección para cada granja utilizando datos recogidos durante la campaña de erradicación de forma rutinaria. De esta forma, los rebaños podrían ser clasificados en función de su riesgo de infección y así la vigilancia se podría focalizar en intentar detectar, de una forma más eficiente y economizando los costes, aquellas granjas con la puntuación de riesgo más elevada. En el tercer estudio, la sensibilidad individual de la vigilancia de TBb en mataderos de Cataluña fue evaluada. La probabilidad de detectar un bovino infectado fue estimada mediante el producto de las siguientes probabilidades: 1) probabilidad de que un bovino infectado llegue a matadero presentando lesiones compatibles y detectables macroscópicamente (LDM), 2) probabilidad de que LDM sean detectadas durante la inspección en matadero, 3) probabilidad de que el veterinario oficial de matadero sospeche de TBb y envíe las muestras al laboratorio para su confirmación. La sensibilidad individual de la vigilancia de TBb en los mataderos de bovino de Cataluña, resultó ser de un 31.4% (CI 95%: 28.6-36.2). En el cuarto estudio, la dinámica de transmisión de TBb dentro de un rebaño fue analizada. Para ello se desarrolló un modelo compartimental estocástico SEI (Susceptibles, Expuestos e Infecciosos). Con este modelo se infirieron los parámetros relacionados con la transmisión, en particular el ratio de transmisión (β) y el ratio en el que los animales infectados pasan a ser infecciosos (α). También, debido a la controversia sobre las sensibilidades reportadas de la prueba de la intradermo-tuberculinización simple (IDTs) en condiciones de campo, la probabilidad de detectar tanto los animales infectados como los infecciosos (ϕ y ρ, respectivamente) fue también evaluada. Las distribuciones posteriores de los parámetros modelizados fueron obtenidas mediante el método de las cadenas de Markov Chain Monte Carlo y por métodos de aproximación por computación bayesiana (MCMC-ABC). El promedio obtenido, de 33 rebaños de diferentes áreas de España, para el ratio de transmisión varió entre 0.0001 y 0.0002 por día, y el promedio del ratio de transición de bovinos infectados a infecciosos varió entre 0.011 y 0.0001.
The present PhD Thesis aimed to provide information about the epidemiology of bovine tuberculosis (bTB) in cattle and relevant data for the implementation of a risk based surveillance system. In the first study the space-time variation of the risk of bTB in cattle between 2006 and 2011 was analyzed. The results indicated that in some counties, between some years, the prevalence and the incidence of the disease was higher as compared to the global rate in the rest of the counties of Spain. The analysis of potential risk factors indicated that both, a large number of movements from counties with high incidence (>1%), and presence of bullfighting cattle herds increased the bTB risk. In the second study it was described a risk-based approach for bTB surveillance that is under development in New Zealand. Given that the presence of bTB in a herd is driven by a number of factors including previous infection history, the amount of testing carried out on individual herds, geographic location or herd movement behavior, the objective was to use routinely recorded data to derive a ‘risk score’ for each of these factors and then to combine them to return a composite bTB risk score for each herd. By this way, herds could be ranked and this would enable to focus surveillance in those herds with the highest risk score, providing effective surveillance coverage at a reasonable overall cost. In the third study the individual sensitivity of bovine tuberculosis surveillance in Catalonian slaughterhouses of cattle was assessed. The probability of detection of a bTB-infected cattle by the slaughterhouses in Catalonia was estimated as the product of three consecutive probabilities: P1) the probability that a bTB-infected animal arrived at the slaughterhouse presenting Macroscopically Detectable Lesions (MDL); P2) the probability that MDL were detected by the routine meat inspection procedure, and P3) the probability that the veterinary officer suspected of bTB and sent the sample for laboratory confirmation. The mean individual bTB surveillance sensitivity of the different cattle slaughterhouses in Catalonia obtained in this study was 31.4% (CI 95%: 28.6-36.2). In the fourth study a stochastic compartmental SEI (Susceptible, Exposed (latent), and Infectious) model was developed to mimic Bovine tuberculosis (bTB) within-herd transmission dynamics. This model was used to infer several parameters related to bTB spread within Spanish cattle farms, in particular the cattle-to-cattle transmission rate (β) and the rate at which infected cattle become infectious (α). Also, given the controversy over the sensitivities of the single intradermal tuberculin test (SIT) application in field conditions, the probability of detection of both infected and infectious cattle (ϕ and ρ, respectively), were also evaluated. A Markov Chain Monte Carlo-Approximate Bayesian Computation (MCMC-ABC) method was used to generate posterior distributions and the mean within herd transmission rate (β) estimated in 33 Spanish herds varied between 0.0001 and 0.0002 per day, and the mean rate at which infected cattle become infectious (α) varied between 0.011 and 0.0001.

El objetivo de esta tesis ha sido aumentar el conocimiento sobre la epidemiología y el control de la Tuberculosis Bovina (TBb) e investigar factores sociológicos que podrían obstaculizar su erradicación en España. En el primer estudio, desarrollamos un modelo que permitió estimar los parámetros de transmisión de la TBb dentro de los rebaños utilizando datos de la campaña de erradicación. Dichos parámetros se emplearon para simular el número medio de casos secundarios causados ​​por un solo animal infectado introducido en un rebaño (Rh), considerando diferentes frecuencias de control. El coeficiente medio de transmisión fue de 5,2 animales infectados por animal infeccioso y año; sin embargo, los resultados evidenciaron una gran variabilidad entre los 22 rebaños estudiados, con valores que oscilaron entre 1,8 y 8,3. La duración media del período de latencia fue 3,2 meses, con un rango intercuartil de 2,4 a 5,4 meses. Considerando un intervalo de 6 meses entre las pruebas, el valor medio de Rh fue 0,23, aumentando a 0,82 para intervalos anuales, y a 2 y 3,5 para intervalos de pruebas de 2 y 4 años, respectivamente. En el segundo estudio se evaluó la eficiencia de los componentes del sistema de vigilancia: vigilancia de rutina, vigilancia en mataderos y pruebas pre-movimientos; y su variabilidad entre las provincias españolas con una versión modificada del modelo desarrollado. Bajo las condiciones españolas, la sensibilidad (probabilidad de detección por año) del sistema de vigilancia fue 79,7% y el tiempo medio hasta la detección de 221,6 días. La vigilancia de rutina fue el componente más eficiente, mientras que la eficacia de la vigilancia en matadero y las pruebas pre-movimientos fue menor; aunque estos componentes también contribuyeron a la detección de algunos rebaños infectados. La eficiencia de los diferentes componentes de vigilancia entre las provincias fue muy variable, pero sin un patrón espacial evidente. Nuestros resultados muestran que, en muchas provincias, la intensidad de la vigilancia no se correlaciona con la prevalencia. En el tercer estudio, utilizamos enfoques cualitativos para investigar opiniones y actitudes de ganaderos y veterinarios hacia el programa de erradicación. Para ello se emplearon entrevistas exploratorias y entrevistas en profundidad. Los principales resultados sugirieron que el programa se percibe como una obligación impuesta por la ley sin una adecuada motivación. La compleja epidemiología de la TBb combinada con una falta de conocimiento y carencias en la comunicación contribuyen a generar desconfianza hacia las medidas de control y, a su vez, a la generación de diferentes tipos de conjeturas sobre la enfermedad. También se mencionó una baja fiabilidad en la prueba cutánea, así como presiones a los veterinarios durante el saneamiento. En general, no se perciben beneficios de ser libres y los ganaderos perciben agravios comparativos respecto a la fauna silvestre, otros reservorios domésticos y granjas de lidia. En el cuarto estudio, los factores sociológicos previamente identificados se investigaron mediante un cuestionario estructurado, entrevistando telefónicamente a 706 ganaderos y 180 veterinarios. Un análisis de correspondencia múltiple, seguido de un análisis de conglomerados, nos permitió identificar tres perfiles de opinión; además, se desarrolló un modelo de regresión logística para cuantificar las principales diferencias entre los grupos. Dichos perfiles se diferenciaron principalmente por su opinión sobre las pruebas de diagnóstico, su percepción sobre el impacto de la TBb y la importancia de otras especies domésticas y silvestres. Algunas personas mostraron actitudes positivas y otras negativas hacia el programa, y un tercer grupo una clara tendencia a no responder. Entre los ganaderos se observaron perfiles opuestos mientras que los veterinarios fueron más homogéneos y la mayoría de ellos expresaron una actitud positiva; sin embargo, algunos veterinarios mostraron una actitud negativa que merece particular atención.
The present PhD thesis aimed to increase knowledge on bTB epidemiology and control and to investigate sociological factors that might hinder the success of the bTB eradication programme. In the first study, we developed a stochastic dynamic model that allowed estimating the cattle-to-cattle bTB transmission parameters within Spanish herds, using field data from the eradication campaign. Then, we used those parameters to simulate the average number of secondary cases caused by a single infected animal introduced into a herd (Rh), considering different control frequencies. The median transmission coefficient () was 5.2 newly infected animals per infectious animal per year; however, results evidenced a great variability in the estimates among the 22 study-herds, with median estimates ranging between 1.8 and 8.3. The overall median duration of the latent period () was 3.2 months, with an interquartile range varying from 2.4 to 5.4 months. Considering a 6-month interval between tests, the mean Rh was 0.23, increasing to 0.82 for annual intervals, and to 2.01 and 3.47 with testing intervals of 2 and 4 years, respectively. The second study was directed at evaluating the efficiency of the components of bTB surveillance system: routine skin testing, slaughterhouse surveillance and pre-movement testing; and, to assess their variability among Spanish provinces, by using a modified version of the model previously developed. Under the average Spanish conditions, the overall sensitivity (i.e. probability of detection per year) of the national bTB surveillance system was 79.7% and the mean time until detection 221.6 days. Routine testing was the most efficient component, while the efficiency of slaughterhouse surveillance and pre-movement testing was much lower; although these components also contributed to detection of some infected herds. Looking at the province level, the efficiency of the different components of the bTB surveillance varied significantly, but no obvious spatial pattern was identified. Our results evidence that in many Spanish provinces, the intensity of surveillance efforts was not correlated to the herd prevalence in the area. In the third study, we used qualitative approaches to investigate opinions and attitudes of farmers and veterinarians toward the Spanish bTB eradication programme. Face-to-face exploratory interviews were used to identify main themes, followed by in-depth interviews. Main results suggested that the bTB programme is perceived as a law enforcement duty without an adequate motivation of some stakeholders. The complex bTB epidemiology combined with gaps in knowledge and weak communication among stakeholders contributed to generate disbeliefs towards control measures and, in turn, different kinds of guesses on the disease. Low reliability in the skin test was expressed and some pressures faced by private veterinarians during field activities also emerged. People perceived very few benefits of being bTB-free and comparative grievances to wildlife, other domestic reservoirs and bullfighting farms arose. In the fourth study, the sociological factors previously identified were investigated through a structured questionnaire, telephonically interviewing a sample of 706 farmers and 180 veterinarians. Multiple Correspondence Analysis, followed by Hierarchical Clustering on Principal Components were used to identify opinion profiles; and, a logistic regression model was developed to quantify the main differences between groups. Different attitudes toward the bTB eradication programme were characterised by opinions on the bTB diagnostic tests, the perception on the impact of bTB and the importance of other domestic and wildlife species. There were people with positive and with negative attitudes toward the programme and a third group with a clear tendency to not respond. Opposite profiles were observed among farmers. Differently, veterinarians were more homogeneous and the vast majority of them expressed a positive attitude; however, some veterinarians showed a negative attitude toward the bTB eradication programme, which deserve a special attention.

Farm, cattle group and individual bovine risk factors for bovine tuberculosis (bTB) in cattle herds in the South West of England were explored. A cohort study using 148 well characterised cattle herds was conducted in SW England 2001-2004. The study was set up in areas affected by foot-and-mouth disease in 2001 and all farms were taking part in the Randomised Badger Culling Trial (RBCT). The use of a standard questionnaire and national data records from the skin intradermal cervical comparative tuberculin test (SICCT) and from the British Cattle Movement Service (BCMS) databases were combined. The two main statistical techniques used were survival analysis and multilevel logistic regression with random effects. Associations with the risk of herd breakdown with bTB were explored using survival analysis. The main factors associated with disclosure of reactor cattle were the purchase of cattle from markets and the storage of slurry and manure in close containment. In the investigation of the risk of an individual bovine animal becoming a reactor using multilevel logistic regression with random effects analysis, explanatory variables at herd, individual cattle and test levels, were explored. The potential exposure to reactor cattle in previous tests was the most significant finding as a risk for a bovine animal reacting at a current test. Only 9/19,027 cattle became reactors if they had not been exposed to a reactor animal previously. When the risk of an animal group having at least one reactor disclosed in the group was investigated using the location of the animal groups within the farm by monthly periods, the risk increased with the number of cattle in the groups when these were housed and with the presence of badgers in the fields when they were grazing. This thesis has provided a deep investigation into the risk factors that can affect the introduction and persistence of infection with M. bovis in cattle herds, and the importance that cattle play in these factors has been highlighted.

A Espanya, la prevalença de ramats amb tuberculosi ha disminuït del 11,1% el 1986 a 1,3% el 2011. Malgrat aquesta reducció en la prevalença, en els últims anys s'ha moderat el descens i l'actual situació epidemiològica de bTB planteja un desafiament cara a la consecució del estatus de país oficialment indemne de tuberculosi. Entre el 50 i el 60% dels ramats positius detecta cada any, són nous ramats positius, i la resta són ramats on la infecció persisteix des de l'any anterior. No es coneixen quines circumstàncies epidemiològiques condueixen a la introducció o la persistència de la infecció. Per tant, l'objectiu d'aquesta tesi és millorar el coneixement de l'epidemiologia de la bTB a Espanya mitjançant l'avaluació de les causes més probables d'infecció i els factors relacionats amb els ramats infectats de manera persistents. Per a l'estimació de les causes més probables d'introducció de la infecció en un ramat hem desenvolupat una metodologia basada en les diferents vies de transmissió de la bTB entre els ramats. S’han considerat set vies i per cada una s’ha realitzat un arbre de decisió sobre possibles riscos. A cada risc se l’hi ha assignat una probabilitat basada en opinió d'experts. Per a la gestió de dades i per al càlcul de les probabilitats de cada una de les diferents causes possibles s’han creat un parell de macros. D'acord amb els resultats dels 816 ramats estudiats (casos detectades principalment els anys 2010 i 2011), la majoria dels casos serien deguts al ressorgiment d'infeccions residuals que havien afectat anteriorment al ramat (39%, n = 316). La introducció de la infecció es va produir pel contacte amb animals silvestres en el 12% dels casos (n = 98), i a través de ramats veïns en el 10% (n = 85). En el 28% (n = 225) dels brots, no s’ha pogut determinar l'origen de la infecció. En 309 ramats, la diferència entre les dues causes amb la probabilitat més alta era petita (menys d'u), de manera, que per a aquestes granges tant la primera com la segona causa serien possibles. Dins d'aquest grup, la primera opció més freqüent va ser la infecció residual (69%, n = 214) i la segona de les opcions més freqüents era compartir les pastures amb altres granges (36%, n = 112) i la interacció amb la fauna silvestre (30%, n = 94). En comparar aquestes conclusions amb les dels veterinaris oficials que havien fet la investigació epidemiològica sobre el terreny, s’obté una concordança baixa; especialment en el cas de fauna silvestre. Dins del grup dels ramats on el veterinari només considerava una causa (és a dir, 309 ramats), en 124 la fauna silvestre va ser considerada com la causa més probable, mentre que nosaltres només ho varem concloure en 33 granges. Aquestes discordances podrien estar relacionades amb un diferent accés a les dades i també a percepcions diferents sobre la importància atribuïda a cada causa. Per tal d'avaluar els factors relacionats amb la persistència de bTB en granges es va realitzar un estudi de casos i controls on es va comparar granges infectades que es va eliminar fàcilment la bTB amb altres on es va tardar més de 5 anys. Totes les granges eren del sud d'Espanya i es van estratificar per grandària del ramat i la ubicació geogràfica (comarca). Es va omplir un qüestionari mitjançant entrevista personal en 150 ramats (80 controls i 70 casos) de les Comunitats d'Andalusia i de Castilla‐la Mancha. D'acord amb els resultats d'aquest estudi, les granges amb més superfície de pastures i amb veïns positius, tenien més dificultats per eradicar la infecció, per tant, eren més propenses a patir un brot de bTB persistent. Les probabilitats de persistència eren entre 1,1 i 5,0 vegades més gran en aquells ramats amb possible contacte amb el bestiar d'un ramat positiu veí. La probabilitat de persistència també es va associar amb la superfície de pastures. Les finques amb àrees de pastura més grans tenien una probabilitat entre 1,2 i 12,7 vegades més alta de tenir dificultats en l’eliminació que les finques amb àrees de pastures més petits. El maneig dels animals positius, com ara utilitzar vedelles de reposició de mares positives o no aïllar els animals positius, així com la presència de cabres dins de la granja semblen tenir també una influència en la persistència de bTB.
En España, la prevalencia de rebaños con tuberculosis ha disminuido del 11,1% en 1986 a 1,3% en 2011. A pesar de esta reducción, en los últimos años se ha moderado el descenso de la prevalencia y la situación epidemiológica actual de bTB plantea un desafío cara a la consecución del estatus de país oficialmente indemne de tuberculosis. Entre el 50 y el 60% de los rebaños positivos detectados cada año, son nuevos rebaños positivos, y el resto son rebaños donde la infección persiste desde el año anterior. No se sabe qué circunstancias epidemiológicas están implicadas en la introducción o la persistencia de la infección. Por tanto, el objetivo de esta tesis es mejorar el conocimiento de la epidemiología de la bTB en España mediante la evaluación de las causas más probables de infección y los factores relacionados con los rebaños infectados de forma persistente. Para la estimación de las causas más probables de introducción de la infección en un rebaño hemos desarrollado una metodología basada en las diferentes vías de transmisión de la bTB entre los rebaños. Se han considerado siete vías y por cada una de ellas se ha realizado un árbol de decisión sobre posibles riesgos. A cada riesgo se le ha asignado una probabilidad basada en opinión de expertos. Para la gestión de datos y para el cálculo de las probabilidades de cada una de las diferentes causas posibles se han creado dos macros. De acuerdo con los resultados de los 816 rebaños estudiados (casos detectados principalmente en los años 2010 y 2011), la mayoría de las nuevas infecciones en realidad son debidas al resurgimiento de infecciones que habían afectado anteriormente al rebaño (39%, n = 316). La introducción de la infección se produjo por el contacto con animales silvestres en el 12% de los casos (n = 98), y a través de rebaños vecinos en el 10% (n = 85). En el 28% (n = 225) de los brotes, no se ha podido determinar el origen de la infección. En 309 rebaños, la diferencia entre las dos causas con la probabilidad más alta era escasa (menos de uno), de manera que para estas granjas tanto la primera como la segunda causa serían posibles. Dentro de este grupo, la primera opción más frecuente fue la infección residual (69%, n = 214) y la segunda de las opciones más frecuentes era compartir los pastos con otras granjas (36%, n = 112) y la interacción con la fauna silvestre (30%, n = 94). Al comparar las conclusiones de nuestro estudio con las de los veterinarios oficiales que habían hecho la investigación epidemiológica sobre el terreno, se obtiene una concordancia baja, especialmente en el caso de fauna silvestre. Dentro del grupo de los rebaños donde el veterinario sólo consideraba una causa (es decir, 309 rebaños), en 124 la fauna silvestre fue la causa considerada como más probable para el veterinario, mientras que nosotros sólo lo concluimos en 33 granjas. Estas discordancias podrían estar relacionadas con diferencias en los datos a los que hemos tenido acceso así como a diferentes percepciones sobre la importancia atribuida a cada causa. Para evaluar los factores relacionados con la persistencia de BTB en granjas se realizó un estudio de casos y controles donde se compararon granjas infectadas donde se eliminó fácilmente la bTB con otras donde se tardó más de 5 años. Todas las granjas eran del sur de España y se estratificaron por tamaño del rebaño y ubicación geográfica (comarca). Se rellenó un cuestionario mediante entrevista personal en 150 rebaños (80 controles y 70 casos) de las Comunidades de Andalucía y de Castilla‐La Mancha. De acuerdo con los resultados de este estudio, las granjas con más superficie de pastos y con vecinos positivos, tenían más dificultades para erradicar la infección, por lo tanto, eran más propensas a sufrir un brote de BTB persistente. Las probabilidades de persistencia eran entre 1,1 y 5,0 veces mayor en aquellos rebaños con posible contacto con un rebaño positivo vecino. La probabilidad de persistencia también se asoció con la superficie de pastos. Las fincas con áreas de pasto mayores tenían una probabilidad entre 1,2 y 12,7 veces más alta de tener dificultades en la eliminación que las fincas con áreas de pastos más pequeños. El manejo de los animales positivos, tales como utilizar terneras de reposición de madres positivas o no aislar los animales positivos, así como la presencia de cabras dentro de la granja parecen tener también una influencia en la persistencia de la bTB.
In Spain, herd prevalence has decreased from 11.1% on 1986 to 1.3% on 2011. Despite this reduction on the prevalence, in the last years there has been just a moderate decline and the current bTB epidemiological situation poses a serious challenge towards the achievement of a national official tuberculosis free (OTF) status. In the country, approximately between 50 and 60% of the total bTB positive herds detected each year, are new positive herds, and the rest of the positives are herds that persist from the previous year. There is not a clear knowledge of the epidemiological circumstances that lead to the introduction or persistence of the infection. Therefore, the aim of this PhD was to improve the understanding of bTB epidemiology in Spain by assessing the most likely causes of infection and factors related with bTB persistent herds. To estimate the most likely causes of introduction of the infection on a herd we developed a methodology based on bTB routes of transmission between herds using decision trees. We considered seven routes as a possible cause of herd breakdown. In order to discriminate among them, probabilities were assigned within each decision tree based on expert opinion. Macros were used for data management and to calculate the probabilities of the different possible causes. According to the results of the 816 studied breakdowns (detected mainly in 2010 and 2011) most of the cases could be resurgence of residual infections that had previously affected the herd (39%, n=316). New introductions of the infection were produced by contact with wildlife in 12% of cases (n=98), and by neighboring herds in 10% of them (n=85). In 28 % (n=225) of the breakdowns, the origin of the infection remained unknown. In 309 herds, the difference between the first and the second cause with the higher probability was small (i.e., less than 1) so, for these herds, first and second possible causes of infection could be considered. Within this group the most frequent first option was residual infection (69%, n=214) and the most frequent second options were sharing pastures with other herds (36%, n=112) and interaction with wildlife (30%, n=94). The results of the comparisons between our conclusions and the ones of the veterinary officers conducting the epidemiological investigation on the field evidenced a low agreement. The lowest agreement was in the case of “wildlife”. Within the group of herds where the veterinary officer just considered one cause (i.e., 309 herds) in 124 Wildlife was considered as the most likely cause, while we just found evidences to suspect of this in 33 farms. These discrepancies could be related to differences on access to data and perception about the importance attributed to the different causes. In order to assess factors related to bTB persistence we conducted a case‐control study and compared persistent versus transient bTB infected farms from southern Spain. Farms were matched by herd size and geographical location (county). A questionnaire by personal interview was carried on 150 herds (80 controls and 70 cases) from Andalusia and Castilla La Mancha regions. According to the results of this study, farms with large pasture areas and positive neighbors had more difficulties in eradicating the disease and therefore, were more likely to suffer a persistent bTB outbreak. The odds of bTB persistence were between 1.1 and 5.0 times higher in those herds that had the possibility of contact with cattle from a neighbor positive herd. The probability of bTB persistence was also associated with the area of the pasture. Farms with larger pasture areas had odds between 1.2 and 12.7 times higher of having a persistent bTB episode than farms with smaller pasture areas. Management of positive animals such as making replacement from positive herds or not isolating positive animals and the presence of goats within the farm seem to have also an influence on bTB persistence.

The study of human palaeopathology has developed considerably in the last three decades resulting in a structured and standardised framework of practice, based upon skeletal lesion patterning and differential diagnosis. By comparison, disarticulated zooarchaeological assemblages have precluded the observation of lesion distributions, resulting in a dearth of information regarding differential diagnosis and a lack of standard palaeopathological recording methods. Therefore, zoopalaeopathology has been restricted to the analysis of localised pathologies and ‘interesting specimens’. Under present circumstances, researchers can draw little confidence that the routine recording of palaeopathological lesions, their description or differential diagnosis will ever form a standard part of zooarchaeological analysis. This has impeded the understanding of animal disease in past society and, in particular, has restricted the study of systemic disease. This research tackles this by combining the disciplines of human palaeopathology and zoopalaeopathology and focusing on zoonotic disease. The primary aim of this research was to investigate the skeletal manifestation of bTB in cattle, sheep/goat and pig to establish differential diagnostic criteria for its identification in zooarchaeological assemblages. Methods commonplace in human palaeopathology were adapted and applied to zoopalaeopathology, in addition to radiography and aDNA analysis. The results emphasise the difficulties but also the potential associated with the identification of systemic diseases in zooarchaeological assemblages. An approach to the classification of potentially infectious lesions is presented that enables the calculation of crude prevalence in disarticulated assemblages. In addition, the potential for a DNA analysis to shed further light on animal disease in the past is emphasised.
Arts and Humanities Research Council (AHRC)
Many of the images have been removed from the online version due to copyright restrictions. The embargo period for the thesis ended: 16th January 2018.

This study was conducted to confirm the presence of bovine tuberculosis (BTB) and determine its prevalence, based on skin test reactivity, in cattle reared under extensive farming conditions in the Govuro district, Inhambane province, Mozambique. The study was comprised of a primary screening test using the single intradermal test (SIT) in randomly selected animals from Colonato and Sede dip tanks in Govuro. Positive reactors to the SIT were tested again with bovine and avian tuberculin using the single intradermal comparative test (SICTT) 7 weeks after the SIT. The sample size was calculated using Win Episcope 2.0 based on 95% confidence to detect a 2% expected prevalence using the SIT, with a 1% accepted error and accounting for a total population size of 7208. The calculated sample size was 682 animals. To compensate for the probability of 20% default in reading, the sample size was increased to 853. During the testing process (SIT), it was evident from the first 3 reading days that the apparent prevalence (61, 94%) was higher than expected (2%), hence we decided to stop when the total number of cattle was 530. During the testing process (SIT), it was evident from the first 3 reading days that the apparent prevalence (61.94%) was far higher than expected (2%), hence we decided to stop when the total number of cattle was 530. This was due to the fact that, at such a high prevalence, it would not be necessary to achieve as high a precision as 1% accepted error. A sample size of 530 would be sufficient to achieve a precision of 4% accepted error, which was regarded as more than adequate. The 530 cattle, 3 or more years of age, were selected using systematic random sampling from the two dip tanks (Colonato 371 and Sede 159 animals). All animals were identified by numbers painted, dorsally on the sacral region. Out of 530 tested cattle by SIT, 268 were read, and 166/268 (61.94% with 95% confidence interval [CI]: 55.8 – 67.8%) were found positive, with visible swallow at the injection site. Apparent prevalence (AP) was found to be 61.94% while the true prevalence (TP) was 75.92%. The predictive value of a positive result (PV+) was found to be 87.9%. No significant difference in apparent prevalence between the two areas was detected by Fisher’s exact test (P = 0.11). By SICTT, out of 28 animals positive reactors to SIT, 21 were possible to read, and 13/21 (61.9%; 95% CI: 55.1 – 89.3%) were found positive. A three year old bull, positive reactor to the SIT, was slaughtered, and a detailed post mortem was carried out and organs with visible lesions were collected for further laboratory testing (histopathology, culture and isolation of M. Bovis and PCR). Later on, 30 more positive reactors to the SIT test were slaughtered: 25/30 (83.3%) showed visible lesions compatible with BTB, and total condemnation of carcass was made in 3/25 (12%) due to generalized lesions. The high prevalence rate of skin test positive animals as well as gross lesions and histopathology were confirmed to be BTB by the isolation and identification of M. Bovis by culture and PCR. Our results suggest that bovine tuberculosis is highly prevalent in Govuro district and may thus represent a potential health problem of zoonotic tuberculosis in humans. Our results suggest that BTB has reached the plateau phase of endemicity in cattle in Govuro district. In this context, the positive predictive value of the SIT is very high and thus the use of the SICTT as a confirmatory test has a limited value and should not be advocated. Our results further indicate that no other prevalence study of BTB should be conducted in the next few years in Govuro district, unless comprehensive control measures are implemented. The focus of further studies should be on the isolation and the molecular characterization of M. Bovis from cattle and humans in order to assess transmission routes and the role played by BTB in human TB cases in Govuro district. Copyright
Dissertation (MSc (Veterinary Tropical Diseases))--University of Pretoria, 2009.
Veterinary Tropical Diseases
unrestricted

Bovine Tuberculosis (bTb) continues to cause turmoil for farmers and their businesses where farmers have endured the impact of the disease for extensive periods of time such is the longevity of the problem. Connections between animal disease and its social impact on humans were recognised widely during the outbreak of foot and mouth disease (FMD) in 2001. However, despite the apparent impact of bTB on farmers and the rural community, there are few studies that seek to explore and measure these social impacts. The aim of this study is to investigate problems associated with the social impacts of bTB on farmers where levels of personal well-being and farmer’s productivity are measured to establish their quality of life and its relationship with bTB. A conceptual framework was drawn up to capture the themes rising from the literature review considered as vital in establishing the social effects of bTB. This framework was used as the basis in developing a mixed methods structure to the research. This approach combined qualitative interviews and participant observation over a longitudinal time frame of eighteen months with farmers and a quantitative postal survey of a sample of farmers across Wales. The qualitative interviews were undertaken with farmers on sixteen farms within four high risk disease areas in Wales. Its aim was to understand the meaning of well-being to farmers and to identify key factors which influence it and their quality of life. The effects of bTB testing on farmers is observed alongside establishing how farmers have managed with bTB and what coping strategies they have adopted both personally and as part of their working lives. A key aim of the quantitative methodology was to establish levels of personal well-being and productivity amongst farmers using recognised scales, to explore what significant pressures affect farmers on their farms and acquire their attitudes to bTB. In qualitative interviews, farmers identified health, happiness, having a sense of worth with respect from others, and having the freedom to farm in their own right as central components to their well-being. Negative influences on well-being were recognised as the weather, red tape and bureaucracy, financial and aspects which causes pressures relative to farm management. In qualitative interviews, farmers linked the impacts of bTB with perceived poor well-being and described various coping strategies to avoid the consequences of bTB. However, survey data found that farmers with bTB were not statistically significantly more likely to have lower well-being than farmers without bTB. Farmers’ well-being appears to be connected to their trust in the Welsh Government; farmers’ perceived ability to control bTB; and their trust in others (such as vets) to help them avoid bTB. The research therefore presents a new perspective of the extent of the social impacts arising from bTB. Where other studies have indicated a relationship between the well-being of farmers and bTB, the results in this research question the extent to which these impacts exist.

Thesis (PhD)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Bovine tuberculosis (BTB), caused by bacteria of the Mycobacterium tuberculosis complex is reported to cause economic and public health negative impact in countries where it is prevalent. The control of the disease has been a difficult task worldwide. The main object of this thesis was to use molecular tools to generate useful information to contribute to the design of appropriate BTB control measures in Mozambique. To do so we considered a deep knowledge of the BTB history in Mozambique to be essential. The search was largely based on the reports produced annually by the Veterinary Services and other available information. We found reports of BTB in Mozambique as early as 1940. These cases were mainly identified as a result of post-mortem meat inspection. The higher numbers of cases reported were from 8 locations, namely Maputo, Magude, Vilanculos, Beira, Chimoio, Tete, Quelimane and Nampula, and served as a basis to decide the locations to perform prevalence and molecular epidemiologic studies. Prevalence studies were done in 10 districts selected based on the history of a high number of BTB case reports (intentionally biased towards locations presumably with higher prevalence), a high cattle density, but also to represent districts from the south, centre and north of Mozambique. A representative sample was defined, based on all livestock areas or villages in Massingir and Govuro Districts or by randomly selecting small-scale and commercial herds in 8 districts, specifically Manhiça, Chibuto, Buzi, Gondola, Mutarara, Mogovolas, Angoche and Mecanhelas. Results were obtained from 6983 cattle tested using tuberculin testing. Apparent prevalence varied from 0.98% in Massingir to 39.6% in the Govuro, with prevalence as high as 71.4% in some livestock areas/herds. The analysis of risk factors showed no noteworthy difference with respect to the sex of the animal. Younger age had significantly lower odds of infection compared to the older age class. There was a tendency of cattle from small-scale herds to have lower prevalence when compared to the commercial herds. From the prevalence studies, 187 tissue and 41 milk samples from BTB reactors were collected. Additionally 220 tissue samples were obtained from the Central Veterinary Laboratory routine diagnostic work. Samples were subject to bacteriological culture and a collection of 170 M. bovis isolates were obtained. Eight additional isolates were supplied from another study. All isolates were subjected to molecular typing using spoligotyping, and a sub-sample using MIRU-VNTR and regions of difference (RD) analysis. Fifteen different spoligotype patterns were identified of which 8 were not previously registered in the Mbovis.org database. The pattern SB0961 accounted for 61% of the isolates and was found in all areas of the country investigated. We hypothesize that this was one of the first clones to be introduced in Mozambique. Twenty-nine isolates had the pattern SB0140, which is specific for the European 1 (Eu1) clonal complex. Eleven isolates with this spoligotype were subjected to RD analysis, and all isolates had the Eu1 specific deletion. These were all isolated from cattle from the south of Mozambique and the majority from commercial farms that imported cattle, mainly from South Africa, where the Eu1 clonal complex is common. There were no isolates of the African 1 (Af1) or African 2 (Af2) clonal complexes that are frequent in Central-West Africa and East Africa, respectively. The clones identified from different farms and districts, strongly suggest routes of transmission and/or common source of infection. In conclusion, our results show a potential increase in the prevalence of BTB in Mozambique even taking into consideration i) that the selection of locations in our study was biased towards locations with a history of higher BTB prevalence and ii) the use of a more sensitive technique i.e. the testing in the middle neck region as opposed to the testing in the caudal fold as used in previous studies. Even if no cattle to human transmission was found in studies done in Mozambique so far, the evidence of M. bovis shedding through milk and the lack of correct practices to prevent animal to human transmission (consumption of raw milk), strongly suggests that there is zoonotic risk; a subject that needs to be investigated. The results presented in this work also strengthen the need to reinforce the current regulations that require a negative BTB test result before cattle importation. The same should be enforced for the internal movements, as the frequency of shared genotypes (Spoligotype and MIRU) from cattle originating from different parts of the country strongly suggest intra-contry transmission of BTB.
AFRIKAANSE OPSOMMING: Beestering (BTB), wat veroorsaak word deur bakterieë van die Mycobacterium tuberculosis kompleks, het ‘n negatiewe impak op die ekonomiese en publike gesondheid in lande waar dit voorkom. Die beheer van die siekte is ‘n moeilike taak wêreldwyd. Die hoofdoel van hierdie tesis was om molekulêre toetse te gebruik om nuttige inligting te genereer wat sal bydra tot die ontwikkeling van toepaslike BTB beheermaatrëels in Mosambiek. Om dit te kon doen, was dit noodsaaklik om ‘n indiepte kennies te hê van BTB geskiedenis in Mosambiek. Die soektog was gebaseer op jaarlikse verslae van Veearts Dienste en ander beskikbare inligting. Ons het verslae gevind van BTB in Mosambiek so vroeg as 1940. Hierdie gevalle is hoofsaaklik geïdentifiseer as gevolg van roetine na-doodse inspeksie van vleis. Hoër getalle van sulke gevalle is geïdentifiseer in 8 distrikte, naamlik Maputo, Magude, Vilanculos, Beira, Chimoio, Tete, Quelimane en Nampula; en het gedien as ‘n basis vir die seleksie van studieareas vir die voorkoms studies. Voorkoms studies is uitgevoer in 10 distrikte gekies op grond van die geskiedenis van 'n hoër aantal BTB gevalle in hierdie areas (doelbewus bevooroordeeld teenoor plekke vermoedelik met 'n hoër voorkoms), asook‘n hoë digtheid beeste, maar ook om distrikte in die suide, middel en noorde van Mosambiek te verteenwoordig. ‘n Verteenwoordigende steekproef is geïdentifiseer gebaseer op al die vee-gebiede of dorpe in Massingir and Govuro distrikte óf deur kleinskaalse en kommersiële kuddes lukraak te kies in 8 distrikte, spesifiek Manhica, Chibuto, Busi, Gondola, Mutarara, Mogovolas, Angoche en Mecanhelas. Resultate is verkry deur 6983 beeste te toets met behulp van die tuberkulien vel toets. Skynbare voorkoms het gewissel van 0,98 % in Massingir tot 39,6 % in Govuro, met voorkoms so hoog as 71,4 % in sommige vee gebiede/ kuddes. Die ontleding van risiko faktore het geen noemenswaardige verskil met betrekking tot die geslag van die dier gewys nie. Jonger ouderdom diere het ‘n aansienlike laer kans van infeksie gehad in vergelyking met die ouer ouderdom klas. Daar was 'n neiging van beeste van kleinskaalse kuddes om ‘n laer voorkoms te hê in vergelyking met die kommersiële kuddes. Van die voorkoms studies, is 187 weefsel- en 41 melkmonsters van BTB reaktors ingesamel. ‘n Addisionele 220 weefselmonsters is verkry vanaf die Sentrale Veterinêre Laboratorium se roetine diagnostiese werk. Monsters was onderhewig aan bakteriologiese kweking en 'n versameling van 170 M. bovis isolate is verkry. Agt bykomende isolate is voorsien deur 'n ander studie. Alle isolate was onderhewig aan molekulêre-tipering met behulp van spoligotipering en ‘n subgroep met behulp van MIRU-VNTR en analise van genomies diverse areas. Vyftien verskillende spoligotipering patrone is geïdentifiseer, waarvan 8 nie voorheen in die Mbovis.org databasis geregistreer is nie. Die SB0961 patroon is geïdentifiseer vir 61% van die isolate en gevind in alle dele van die land wat ondersoek was. Ons hipotese is dat hierdie een van die eerste klone was wat voorgestel is in Mosambiek. Nege en twintig isolate het die SB0140 patroon gehad wat spesifiek is aan die Europese 1 (EU1) klonale kompleks. Elf isolate met hierdie spoligotipering patroon is verder geanaliseer om genomies diverse areas te identifiseer, waarvan almal die Eu1 spesifieke delesie getoon het. Hierdie isolate is almal geïsoleer uit beeste van die suide van Mosambiek, asook beeste gevind op kommersiele plase wat hoofsaaklik vanuit Suid Afrika invoer- waar die EU1 klonale kompleks algemeen is. Daar is geen isolate van die Afrikaans 1 (AF1) of Afrikaans 2 (AF2) klonale komplekse nie, dikwels gevind in onderskeidelik Sentraal-Wes-Afrika en Oos- Afrika. Isolate wat in verskillende plase en distrikte geïdentifiser is dui roetes van transmissie en/ of a gemeenskaplike bron van infeksie aan. Ten slotte, ons resultate dui op 'n moontlike toename in die voorkoms van BTB in Mosambiek, selfs met inagneming dat i) die keuse van areas in ons studie is bevooroordeeld teenoor areas met 'n geskiedenis van hoër BTB voorkoms en ii) die gebruik van 'n meer sensitiewe tegniek d.w.s. toetsing in die middel nekgebied i.p.v. toetsing in die stert vou soos gebruik in vorige studies. Selfs al is geen bees-na-mens-oordrag gevind nie, is die bewys van M. bovis oordrag deur melk en die gebrek aan korrekte prosedures om dier-na-mens-oordrag te voorkom (verbruik van nie-gepasturiseerde melk), ‘n sterk bewys van die soönotiese risiko; ‘n onderwerp wat ondersoek moet word. Die resultate van hierdie ondersoek beklemtoon die behoefte om die huidige regulasies wat ‘n negatiewe BTB toetsuitslag vereis voor beeste ingevoer word, te versterk. Dieselfde maatreëls moet ingestel word vir interne beweging van beeste, omdat die frekwensie van gedeelde genotipes (Spoligotipering en MIRU) tussen beeste met oorsprong uit verskillende dele van die land aandui dat interne oordrag van BTB plaasvind.

A study was conducted to determine the epidemiological status of bovine tuberculosis in the state of Rio Grande do Sul. The state was divided in seven regions, and in each of them, a pre-established number of farms was randomly sampled. In each farm, cows with age equal to or greater than 24 months were selected at random and submitted to the comparative cervical tuberculin test. The animals whose tests were inconclusive were retested with the same diagnostic procedure within a minimum interval of 60 days. In all, 9,895 animals from 1,067 farms were tested. An epidemiological questionnaire was applied in the farms in order to identify risk factors associated with bovine tuberculosis. The prevalence of infected herds in the state was 2.8% [1.8; 4.0] and that of infected animals was 0.7% [0.4; 1.0]. There was a trend towards a concentration of infected herds in the northern part of the state, with a predominance of dairy and mixed herds. The risk factors associated with the condition of infected herds were being a dairy herd (OR = 2.90 [1.40; 6.13]) and herds with 16 or more cows (OR = 2.61 [1.20; 5.49]). Thus, the best strategy to be adopted by the state is the implementation of surveillance systems to detect and remediate the infected herds, preferably incorporating elements of risk-based surveillance. In addition, the state must carry out a solid action of health education so that the producers test animals for bovine tuberculosis before introducing them in their herds
Um estudo foi realizado para determinar a situação epidemiológica da tuberculose bovina no Estado de Rio Grande do Sul. O Estado foi dividido em sete regiões e em cada uma delas foi aleatoriamente amostrado um número pré-estabelecido de propriedades. Dentro de cada propriedade, fêmeas com idade igual ou superior a 24 meses foram escolhidas aleatoriamente e submetidas ao teste tuberculínico cervical comparativo. Os animais que resultaram inconclusivos foram testados novamente com o mesmo procedimento diagnóstico em intervalo mínimo de 60 dias. Ao todo foram testados 9,895 animais provenientes de 1,067 propriedades. Nas propriedades, foi aplicado um questionário epidemiológico para identificar fatores de risco associados à tuberculose bovina. A prevalência de focos no estado foi de 2.8% [1.8; 4.0] e a de animais 0.7% [0.4; 1.0]. Houve tendência de concentração de focos na parte Norte do estado, caracterizada pelo predomínio de propriedades de leite e mistas Os fatores de risco associados à condição de foco foram exploração leiteira (OR = 2.90 [1.40; 6.13]) e rebanhos com 16 ou mais vacas com pelo menos 24 meses de idade (OR = 2.61 [1.20; 5.49]). Assim, a melhor estratégia a ser adotada pelo estado é a implementação de sistema de vigilância para detecção e saneamento dos focos, de preferência incorporando elementos de vigilância baseada em risco. Além disso, o estado deve realizar uma sólida ação de educação sanitária para que seus produtores passem a testar os animais para tuberculose bovina antes de introduzi-los em seus plantéis

To assist in the evaluation of BCG vaccination in African buffaloes (Syncerus caffer), an infection model for Mycobacterium bovis was established, using an intratonsilar route of inoculation. Two groups of 11 buffaloes each, aged approximately 18 months, were infected with either 3,2 x 102 cfu (low dose) or 3 x 104 (high dose) of virulent buffalo strain M. bovis. A control group of six buffaloes received saline via the same route. The infection status was monitored using the intradermal tuberculin test, an ELISA and a modified interferon-gamma assay. All buffaloes were euthanased 22 weeks post infection and the development of lesions in the left retropharyngeal lymph node was evaluated by macroscopic examination, mycobacterial culture and histopathology. It was found that the high dose caused macroscopic lesions in 9 out of 11 buffaloes that were comparable to that observed in buffaloes with natural disease. Mycobacterium bovis was isolated from all animals in the high dose and from 6 out of 11 buffaloes in the low dose group. The efficacy of a live BCG-Pasteur vaccine was tested in a group of buffalo calves captured in the northern districts of the Kruger National Park from herds with known negative tuberculosis status. Primary and booster vaccinations with BCG (1173P2) were administered to 15 calves, while another 15 were left unvaccinated as control animals. All the buffalo calves were challenged with the high dose of live M. bovis (as determined in the Infection Model) via intratonsilar inoculation. Laboratory tests were able to distinguish between infected and non-infected animals from an early stage. All buffaloes were euthanased 34 weeks after infection and the development of lesions in the lymph nodes of the head, thorax, carcass and abdomen was evaluated by macroscopic examination, mycobacterial culture and histopathology. The lungs were carefully palpated to detect the presence of tuberculous granulomas. Macroscopic lesions in the lymph nodes were found in 10 out of 14 control buffaloes and 7 out of 15 vaccinated animals. The lesions were comparable to that observed in buffaloes with natural infection. The lesion scores of individual animals were generally much higher in the BCG vaccine study than what was experienced with the Infection Model. Mycobacterium bovis was isolated from 12 out of 14 control animals and from 12 out of 15 vaccinated buffaloes. Although fewer vaccinated animals developed tuberculous lesions, the differences between the two groups were not statistically significant and it can be concluded that under the prevailing conditions the BCG vaccine was unable to protect buffalo calves against the establishment of M. bovis infection.
Dissertation (MSc (Tropical Diseases))--University of Pretoria, 2004.
Veterinary Tropical Diseases
unrestricted

Studying the dynamics of pathogen transmission within wildlife populations presents an array of challenges. Where populations are socially structured, this can influence parasite transmission, impacting on the effectiveness of disease management strategies. In this thesis, I focus on a well-studied social mammal, the European badger (Meles meles) which is a key wildlife reservoir of a disease of economic importance; bovine TB (caused by infection with Mycobacterium bovis). The social structuring, characteristic of high density badger populations, is of well-established importance in the transmission of bovine TB and has resulted in unexpected management outcomes. However, little is known about the role of kin structure or host genotype on transmission dynamics. In this thesis, I combine traditional spatial epidemiology and ecological analysis of a well-studied badger population with more novel genetic and genomic approaches. Firstly, I investigate the role of kin structure within badger social groups in determining early life infection risk (Chapter 3). Using host genotype data, I demonstrate that cubs who are related to infected adults experience enhanced infection risks. I then explore the role of badger genotype on outcomes of M. bovis exposure and demonstrate that inbred badgers are more likely to show evidence of progressive infection (Chapter 4). Where the social structure of badgers is stable and unmanaged, this is predicted to result in a stable spatial distribution of M. bovis infection. Motivated by an observation of change in the spatial distribution of M. bovis infection in the study population, in the absence of management, I characterise the attrition of a spatially stable infection distribution (Chapter 5). To explore the drivers of this, I detect changes in the genetic population structure (Chapter 6) and present evidence that the population has experienced a period of demographic flux. Finally, I use a novel dataset generated by whole genome sequencing of M. bovis isolates and present evidence of spatial spread of M. bovis infection across the study population (Chapter 7). To conclude, I discuss how my findings demonstrate how genetic and genomic approaches can complement traditional wildlife epidemiology approaches, how they contribute to our understanding of heterogeneity in transmission dynamics and discuss their implications for wildlife disease management.

Bovine tuberculosis (TB) is a contagious neglected zoonosis of cattle that is prevalent but under-investigated in Cameroon, hence this study was designed to assess the epidemiology of bovine TB in cattle, risks for M. bovis infection in cattle and humans; and public health implications of zoonotic bovine TB in the highlands of Cameroon. A retrospective study of meat inspection records (1994 – 2010) was done to estimate the prevalence of TB lesions in slaughtered cattle in the North West region. The prevalence of bovine TB and anti-bovine TB antibodies in live cattle based on tuberculin skin tests (2 surveys) and immune-chromatographic assays respectively were carried out in the Western and Adamawa highlands of Cameroon. The performance of the tuberculin tests for bovine TB diagnosis in cattle using various tuberculin skin test cut-off points against the detection of anti-bovine TB antibodies (hypothesised risks of exposure) was compared. Suspected TB lesions from slaughtered cattle and infected human sputa were cultured on Lowentein – Jesen and Middlebrook 7H9 media to isolate mycobacteria agents for molecular genotyping using genomic deletion analysis and spoligotyping. Risk factors for exposure and transmission of zoonotic bovine TB infection of cattle and cattle professionals, and its public health significance were determined using structured questionnaires. Seventeen years of meat inspection record revealed that suspect TB lesions were identified in 599 of 129,165 slaughtered cattle at the Bamenda abattoir. The lungs and associated lymph nodes (over 60%) were the most affected tissues. Other results showed that the prevalence of anti-bovine TB antibodies in cattle in the study regions was 37.17%. Chi square statistics revealed that irrespective of the tuberculin test cut-off value (P<0.05; χ2>48), strong associations existed between the detection of anti-bovine TB antibodies and disease status. A 95% confidence interval analysis of the comparative cervical tuberculin tests revealed that the prevalence rates were 4.67% – 7.15%, 12.02% – 15.67% and 20.56% – 24.98% at the ≥ 4mm, ≥ 3mm and ≥ 2mm cut-off points, respectively. Overall, the best test performance was realised at ≥ 3-mm, though the ≥ 2-mm cut-off point predicted more positive reactors. Age, sex, breed and husbandry practices served as significant (P<0.05) risks to the prevalence and exposure of bovine TB in cattle. The feedbacks from cattle professionals suggested that there was high possibility of cattle to cattle and cattle to human transmission of bovine TB such as intimate and repeated animal / animal and animal / human interactions, consuming unpasteurised milk and eating raw meat. Genomic deletion analysis of cultured isolates showed evidence of M. tuberculosis from cattle and M. bovis from human while spoligotyping identified five cattle M. bovis strains; and four spoligotype patterns that had not been previously described anywhere. The study has important epidemiological and public health implications requiring prompt and decisive actions from the Cameroonian authority towards controlling zoonotic bovine TB in both humans and animals. A multidisciplinary approach is needed for further collaborative research and effective control strategies such as enhancing the awareness of people to this deadly disease through continuous education, proper food handling and personal hygiene, healthy husbandry practices and maintenance of the environment.

Despite Africa accounting for ~20% of the global cattle population, prevalence estimates and related risk factors of bovine tuberculosis (bTB), caused by Mycobacterium bovis, are still poorly quantified in many countries across the continent. Control of bTB in Africa is difficult due to poor monitoring of cattle movements and limited abattoir surveillance. Also M. bovis is zoonotic and risk factors for transmission include living in close contact with cattle and consumption of unpasteurised milk. Cattle keeping is integral to some rural populations in Cameroon and understanding the epidemiology of bTB in cattle populations is important both to bovine and public health. Detection of bTB in cattle is difficult due to variability of immune responses to M. bovis infection. The interferon-γ (IFN-γ) assay maybe useful to estimate bTB prevalence and identify bTB risk factors in Cameroon. However its performance can vary at different stages of bTB pathogenesis and in different cattle populations. Recently Fasciola hepatica co-infections have been reported to suppress IFN-γ responses in M. bovis infected cattle but the potential effect with F. gigantica co-infections on bTB prevalence estimates in Cameroon is unknown. An abattoir study was conducted in Cameroon to assess the performance of the IFN-γ assay. In 2012-13; 2064 slaughtered cattle were sampled from Bamenda abattoir (North West Region; NWR) and Ngaoundere abattoir (Vina Division; VD). Individual animal data was collected from routine meat inspection including identification of bTB and Fasciola pathology. Cattle were also tested for bTB using the IFN-γ assay and an M. bovis antibody ELISA. In the absence of a gold-standard diagnostic, the IFN-γ assay was compared to other diagnostic tests to assess agreement and identify factors that affected performance of the assay. Agreement between IFN-γ assay, TB lesion identification and an M. bovis antibody ELISA was poor-moderate, probably partly related to differences in immune response detected. A presence of Fasciola gigantica also increased the odds of false negative IFN-γ assay results. On further investigation co-infected cattle had increased odds of TB lesions and reduced IFN-γ responses that potentially could lead to ~20% reduction in test sensitivity. In an attempt to take into account the potential impact of F. gigantica, when estimating bTB prevalence, an antibody ELISA was developed to detect the exposure in live cattle. To highlight the awareness of disease in cattle-rearing communities, estimate prevalence and identify risk factors of bTB in cattle populations; two cross-sectional studies were conducted in 2013. A stratified clustered cross-sectional study of pastoral cattle herds, in the NWR and the VD, sampled 1448 pastoral cattle reared by 100 pastoralists. A smaller cross-sectional study sampled 60 dairy cattle from 46 small-holder co-operative dairy farmers. Individual animal data and herd-level data were collected and animals were screened by both the single comparative intradermal skin test (SCITT) and IFN-γ assay. Awareness of zoonotic TB was low yet consumption of raw milk was high in cattle-keeping communities highlighting the need for accurate bTB prevalence estimates. Despite the high awareness of the clinical presentation of bTB, clinical signs identified by pastoral herdsmen were not associated with cattle being bTB positive. The SCITT was used to compare two manufacturers cut offs for the IFN-γ assay, ≥0.05 and ≥0.1, and highlighted that these two diagnostics may detect different populations of bTB positive cattle. Using the IFN-γ assay at ≥0.1, bTB prevalence was highest in dairy cattle (21.67%) and was also present in pastoral cattle in the NWR and VD (11.33% and 6.55% respectively). Importantly, as F. gigantica is endemic in Cameroon and its influence could mean the true prevalence of bTB could be higher. Female pastoral cattle were at lower odds of being IFN-γ assay positive potentially due to immunosuppressive factors had lower odds of disease. Husbandry practices also decreased the odds of being IFN-γ assay positive such as drinking from streams, antelope and contact with herds at grazing. Age increased the odds of pastoral cattle being IFN- assay positive potentially being a confounder to chronicity of bTB and other co-infections may influence IFN-γ responses. Dairy cattle herds had different risk factors for being IFN- positive likely due to differences in husbandry practices. Considering the potential risk to public health of M. bovis this thesis highlights the extent of bTB across two major cattle keeping regions in Cameroon and the public health risk in cattle-rearing communities. Furthermore the relationship between Fasciola co-infection and IFN- responses to M. bovis described has potential implications for bTB diagnosis in cattle populations where the parasite is present across the globe.

Bovine tuberculosis (bTB) is one of the principal concerns currently facing the livestock industry in England. The disease has spread dramatically in recent years and is costing the country millions of pounds each year. Tens of thousands of cattle are being slaughtered annually; a huge financial and emotional burden to affected farmers. While various measures to control the disease have been taken, none have been successful in bringing it under control. Instead bTB continues to spread unabated. The essence of the bTB problem is that it necessitates industry buy-in in order to implement disease control measures. It is therefore not simply an issue of regulation. Current government bTB control policy emphasises communication and cooperative working across the government and the farming industry, coupled with cost and responsibility sharing. However, previous studies have shown that relationships between farmers and the government are already strained, engendered by a sense of distrust and a lack of confidence. Although some social science work has been conducted within the field of disease control and particularly bTB, the majority focuses on farmers‘ attitudes towards government policy and disease control. However, in order to implement successful disease control measures it is necessary to explore the ways in which farmers currently respond to bTB, and how their responses may be recognised by, and incorporated into, successful policy. While previous research has identified the important role of the wider social context in influencing farmers‘ attitudes and behaviour, no studies have yet provided an in-depth analysis of farmers‘ social networks in relation to bTB. In response, this study uses the lens of social capital to explore the various social ties which enhance or constrain farmers‘ capacity to respond to bTB. An iterative, mixed methods approach is adopted across two phases of research. The first incorporates twenty in-depth qualitative farmer interviews, exploring various aspects of bTB risk and response strategies as well as the core features of social capital. This informs a second, quantitative phase, in which data are iii gathered through a self-completion postal survey of 374 farmers in the South West of England. A farmer segmentation model is developed using factor and cluster analysis and two farmer groups are identified. The first group represents vulnerable farmers who are concerned about the negative impacts of bTB, and who are internally focused with respect to their networks. Characteristically, they exhibit strong relationships with others from within the farming community. In comparison, the second group are more resilient and less concerned about the impacts of bTB on their farm business. These farmers are externally focused, mainly seeking information from the government, the National Farmers‘ Union and their vet. The role of various forms of social capital is explored and an important distinction between the two farmer groups is found. Vulnerable farmers tend to be members of close networks of other farmers (bonding social capital), while resilient farmers are more likely to enjoy positive relationships with those from outside the farming community including vets (bridging social capital) and the government (linking social capital). However, while the research findings suggest that bridging and linking social capital can positively influence farmers‘ attitudes towards bTB, they do not necessarily lead to positive disease control behaviour. Statistical analysis of the data reveals no significant differences between the farmer groups in terms of their uptake of biosecurity measures, which represents an important disease avoidance strategy. A disjuncture between farmers‘ attitudes and their behaviour is therefore identified. The research concludes that investment in social capital between the government and farmers should form a core area of policy through providing opportunities for consistent and regular contact, allowing for the development of trusting and productive relationships. The current situation, characterised by low levels of trust and limited uptake of recommended disease control measures by farmers, indicates incoherence with contemporary policy discourses. A better understanding of the role of social capital in influencing farmer attitudes and behaviour will enable policy makers to increase the ability of farmers to respond to bTB risk, either through disease avoidance or through more effective management and coping mechanisms.