Journal articles: 'Asymptomatic carriage'

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Curry, Scott R., Michelle Hecker, Justin O’Hagan, Preeta K. Kutty, Heba Alhmidi, Y. Karen Ng Wong, Jennifer Cadnum, et al. "2371. A Multicenter Cohort Study of the Natural History of Clostridioides difficile Colonization and Infection." Open Forum Infectious Diseases 6, Supplement_2 (October 2019): S818. http://dx.doi.org/10.1093/ofid/ofz360.2049.

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Abstract Background Asymptomatic carriage of toxigenic Clostridioides difficile strains is common in healthcare settings. However, the natural history of C. difficile colonization and infection is not well understood, particularly for patients with new acquisition of carriage. Methods In 3 tertiary care hospitals and affiliated long-term care facilities (LTCFs), we conducted a 6-month cohort study to identify patients with new acquisition of rectal carriage of toxigenic C. difficile and determined the duration and burden of carriage. Asymptomatic carriage was defined as transient if only 1 culture was positive with negative cultures before and after or persistent if 2 or more cultures were positive; clearance was defined as 2 consecutive negative rectal cultures. Results Of 4180 patients with negative initial cultures, 144 (3%) acquired asymptomatic carriage of toxigenic C. difficile, and 19 (13%) of these carriers subsequently were diagnosed with CDI. Of 50 asymptomatic carriers analyzed for duration of carriage, 33 (66%) had transient carriage of toxigenic C. difficile and 17 (34%) had persistent carriage. For persistent carriers, the estimated median time to clearance of colonization was 76 days (range, 41 to 95 days from acquisition). Ten of 17 (59%) persistent carriers had a high burden of carriage (defined as > 25 colonies recovered from 1 or more swabs) vs. only 1 of 33 (3%) transient carriers (P < 0.001). Conclusion Acquisition of asymptomatic carriage of toxigenic C. difficile carriage was common among patients in healthcare facilities, but most carriers had transient low-level carriage. Additional studies are needed to determine whether a higher burden of carriage predicts subsequent risk of transmission. Disclosures All authors: No reported disclosures.

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QUILLIAM, R. S., P. CROSS, A. PRYSOR WILLIAMS, G. EDWARDS-JONES, R. L. SALMON, D. RIGBY, R. M. CHALMERS, D. Rh THOMAS, and D. L. JONES. "Subclinical infection and asymptomatic carriage of gastrointestinal zoonoses: occupational exposure, environmental pathways, and the anonymous spread of disease." Epidemiology and Infection 141, no. 10 (May 10, 2013): 2011–21. http://dx.doi.org/10.1017/s0950268813001131.

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SUMMARYAsymptomatic carriage of gastrointestinal zoonoses is more common in people whose profession involves them working directly with domesticated animals. Subclinical infections (defined as an infection in which symptoms are either asymptomatic or sufficiently mild to escape diagnosis) are important within a community as unknowing (asymptomatic) carriers of pathogens do not change their behaviour to prevent the spread of disease; therefore the public health significance of asymptomatic human excretion of zoonoses should not be underestimated. However, optimal strategies for managing diseases where asymptomatic carriage instigates further infection remain unresolved, and the impact on disease management is unclear. In this review we consider the environmental pathways associated with prolonged antigenic exposure and critically assess the significance of asymptomatic carriage in disease outbreaks Although screening high-risk groups for occupationally acquired diseases would be logistically problematical, there may be an economic case for identifying and treating asymptomatic carriage if the costs of screening and treatment are less than the costs of identifying and treating those individuals infected by asymptomatic hosts.

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Marignac, G., G. Fall, E. Prina, M. Lebastard, G. Milon, and L. Nicolas. "Cutaneous asymptomatic carriage of Leishmania spp." Veterinary Dermatology 15, s1 (August 2004): 18. http://dx.doi.org/10.1111/j.1365-3164.2004.00410_5-5.x.

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FRIEDEN, ILONA J. "Tinea capitis: asymptomatic carriage of infection." Pediatric Infectious Disease Journal 18, no. 2 (February 1999): 186–90. http://dx.doi.org/10.1097/00006454-199902000-00026.

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Vargas, Sergio L., Carolina Angelica Ponce, Catherine Andrea Sanchez, Ana Victoria Ulloa, Rebeca Bustamante, and Guido Juarez. "Pregnancy and Asymptomatic Carriage ofPneumocystis jiroveci." Emerging Infectious Diseases 9, no. 5 (May 2003): 605–6. http://dx.doi.org/10.3201/eid0905.020660.

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Mun, MSS, T. Yap, AD Alnuaimi, GG Adams, and MJ McCullough. "Oral candidal carriage in asymptomatic patients." Australian Dental Journal 61, no. 2 (May 27, 2016): 190–95. http://dx.doi.org/10.1111/adj.12335.

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Lemay, Julie-Anne, Leah J. Ricketson, and James D. Kellner. "Trends in Asymptomatic Nasopharyngeal Streptococcus pneumoniae Carriage with qPCR and Culture Analysis." Microorganisms 10, no. 10 (October 20, 2022): 2074. http://dx.doi.org/10.3390/microorganisms10102074.

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We previously reported trends in pneumococcal nasopharyngeal carriage in the post-PCV13 era as detected by conventional culture methods. Our current aim is to assess if there are fundamental differences in the clinical and demographic features of children who have pneumococcal carriage detected by qPCR compared with culture analysis. The CASPER team conducted point-prevalence surveys in 2016 in healthy children in Calgary to determine trends in overall and serotype-specific pneumococcal nasopharyngeal carriage. Being 18 months of age (p = 0.009), having at least one sibling under 2 years of age (p = 0.04), having only sibling(s) over 2 years of age (p = 0.001), and childcare attendance (p = 0.005) were associated with carriage by qPCR methods only. Having only sibling(s) older than 2 years of age was associated with carriage detected by both qPCR and culture methods (p = 0.001). No clinical factors were associated with carriage detected by both qPCR and culture compared to qPCR methods only. Both analyses are suitable methods to detect carriage; however, qPCR analysis is more sensitive and more cost-effective. As there are no fundamental differences in the children that have pneumococcal nasopharyngeal carriage detectable by qPCR methods compared to conventional culture methods, molecular analysis may be a preferable option for future carriage studies.

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Flores, Anthony R., Brittany E. Jewell, Dedipya Yelamanchili, Randall J. Olsen, and James M. Musser. "A Single Amino Acid Replacement in the Sensor Kinase LiaS Contributes to a Carrier Phenotype in Group A Streptococcus." Infection and Immunity 83, no. 11 (August 17, 2015): 4237–46. http://dx.doi.org/10.1128/iai.00656-15.

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ABSTRACTDespite the high frequency of asymptomatic carriage of bacterial pathogens, we understand little about the bacterial molecular genetic underpinnings of this phenomenon. To obtain new information about the molecular genetic mechanisms underlying carriage of group AStreptococcus(GAS), we performed whole-genome sequencing of GAS strains recovered from a single individual during acute pharyngitis and subsequent asymptomatic carriage. We discovered that compared to the initial infection isolate, the strain recovered during asymptomatic carriage contained three single nucleotide polymorphisms, one of which was in a highly conserved region of a gene encoding a sensor kinase,liaS, resulting in an arginine-to-glycine amino acid replacement at position 135 of LiaS (LiaSR135G). Using gene replacement, we demonstrate that introduction of the carrier allele (liaSR135G) into a serotype-matched invasive strain increased mouse nasopharyngeal colonization and adherence to cultured human epithelial cells. The carrier mutation also resulted in a reduced ability to grow in human blood and reduced virulence in a mouse model of necrotizing fasciitis. Repair of the mutation in the GAS carrier strain restored virulence and decreased adherence to cultured human epithelial cells. We also provide evidence that the carrier mutation alters the GAS transcriptome, including altered transcription of GAS virulence genes, providing a potential mechanism for the pleiotropic phenotypic effects. Our data obtained using isogenic strains suggest that theliaSR135Gmutation in the carrier strain contributes to the transition from disease to asymptomatic carriage and provides new information about this poorly described regulatory system in GAS.

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Slimmen, Lisa J. M., Hettie M. Janssens, Annemarie M. C. van Rossum, and Wendy W. J. Unger. "Antigen-Presenting Cells in the Airways: Moderating Asymptomatic Bacterial Carriage." Pathogens 10, no. 8 (July 28, 2021): 945. http://dx.doi.org/10.3390/pathogens10080945.

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Bacterial respiratory tract infections (RTIs) are a major global health burden, and the role of antigen-presenting cells (APCs) in mounting an immune response to contain and clear invading pathogens is well-described. However, most encounters between a host and a bacterial pathogen do not result in symptomatic infection, but in asymptomatic carriage instead. The fact that a pathogen will cause infection in one individual, but not in another does not appear to be directly related to bacterial density, but rather depend on qualitative differences in the host response. Understanding the interactions between respiratory pathogens and airway APCs that result in asymptomatic carriage, will provide better insight into the factors that can skew this interaction towards infection. This review will discuss the currently available knowledge on airway APCs in the context of asymptomatic bacterial carriage along the entire respiratory tract. Furthermore, in order to interpret past and futures studies into this topic, we propose a standardized nomenclature of the different stages of carriage and infection, based on the pathogen’s position with regard to the epithelium and the amount of inflammation present.

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Ong-Lim, Anna Lisa. "Meningococcal Disease and Carriage in the Philippines: A Review of Recent Data." Pediatric Infectious Disease Society of the Philippines Journal 23, no. 1 (June 6, 2022): 5–9. http://dx.doi.org/10.56964/pidspj20222301003.

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This article reviews recent data on meningococcal disease and carriage in the Philippines. It aims to provide information on the epidemiology of meningococcal disease, its carriage, data on prevention, and the impact of vaccination on disease and carriage. The World Health Organization considers the Philippines as having low endemicity for meningococcal disease. However, current data underestimates the true burden in the country due to many factors. In recent years, data from the Philippines show a high case-fatality rate since only the septicemic form is being reported. Studies on asymptomatic meningococcal carriage rates are sparse, with one study by Gonzales, et al. investigating the prevalence of meningococcal nasopharyngeal carriage in Filipinos aged 5-24 years old living in an urban setting. The study showed that the overall prevalence of carriage was 3.7% and was highest (9%) among the 10-14 age group. Serogroup B was the most common isolate. Effective meningococcal vaccines are available. Although not included in the National Immunization Program, medical societies recommend giving vaccines to individuals at high risk of infection. Data on local epidemiology accounting for the disease and asymptomatic carriage are important to strengthen future programs on immunization and prevention of meningococcal disease.

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Sirinavin, S., L. Pokawattana, and A. Bangtrakulnondh. "Duration of Nontyphoidal Salmonella Carriage in Asymptomatic Adults." Clinical Infectious Diseases 38, no. 11 (June 1, 2004): 1644–45. http://dx.doi.org/10.1086/421027.

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Mehta, G., A. Malik, S. Singh, and S. Kumari. "Asymptomatic Salmonella senftenberg carriage in a neonatal ward." Journal of Hospital Infection 22, no. 4 (December 1992): 317–22. http://dx.doi.org/10.1016/0195-6701(92)90017-g.

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Ruimy, Raymond, Aminata Maiga, Laurence Armand-Lefevre, Ibrahim Maiga, Amadou Diallo, Abdel Karim Koumaré, Kalilou Ouattara, et al. "The Carriage Population of Staphylococcus aureus from Mali Is Composed of a Combination of Pandemic Clones and the Divergent Panton-Valentine Leukocidin-Positive Genotype ST152." Journal of Bacteriology 190, no. 11 (March 28, 2008): 3962–68. http://dx.doi.org/10.1128/jb.01947-07.

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ABSTRACT Staphylococcus aureus is an important human pathogen, but it appears more commonly in asymptomatic colonization of the nasopharynx than in cases of invasive disease. Evidence concerning the global population structure of S. aureus is limited by the overrepresentation in the multilocus sequence testing database of disease isolates recovered from Western Europe, the Americas, Australia, and Japan. We address this by presenting data from the S. aureus carriage population in Mali, the first detailed characterization of asymptomatic carriage from an African population. These data confirm the pandemic spread of many of the common S. aureus clones in the carriage population. We also note the high frequency (∼24%) of a single divergent genotype, sequence type 152 (ST152), which has not previously been recovered from nasal carriage isolates but corresponds to a sporadic Panton-Valentine leukocidin (PVL)-positive, community-acquired methicillin-resistant S. aureus clone noted mostly in Central Europe. We show that 100% of the ST152 isolates recovered from nasal carriage samples in Mali are PVL positive and discuss implications relating to the emergence and spread of this virulent genotype.

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Chisholm, Rebecca H., Patricia T. Campbell, Yue Wu, Steven Y. C. Tong, Jodie McVernon, and Nicholas Geard. "Implications of asymptomatic carriers for infectious disease transmission and control." Royal Society Open Science 5, no. 2 (February 2018): 172341. http://dx.doi.org/10.1098/rsos.172341.

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For infectious pathogens such as Staphylococcus aureus and Streptococcus pneumoniae , some hosts may carry the pathogen and transmit it to others, yet display no symptoms themselves. These asymptomatic carriers contribute to the spread of disease but go largely undetected and can therefore undermine efforts to control transmission. Understanding the natural history of carriage and its relationship to disease is important for the design of effective interventions to control transmission. Mathematical models of infectious diseases are frequently used to inform decisions about control and should therefore accurately capture the role played by asymptomatic carriers. In practice, incorporating asymptomatic carriers into models is challenging due to the sparsity of direct evidence. This absence of data leads to uncertainty in estimates of model parameters and, more fundamentally, in the selection of an appropriate model structure. To assess the implications of this uncertainty, we systematically reviewed published models of carriage and propose a new model of disease transmission with asymptomatic carriage. Analysis of our model shows how different assumptions about the role of asymptomatic carriers can lead to different conclusions about the transmission and control of disease. Critically, selecting an inappropriate model structure, even when parameters are correctly estimated, may lead to over- or under-estimates of intervention effectiveness. Our results provide a more complete understanding of the role of asymptomatic carriers in transmission and highlight the importance of accurately incorporating carriers into models used to make decisions about disease control.

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HARRIES, M., J. DREESMAN, S. RETTENBACHER-RIEFLER, and E. MERTENS. "Faecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae and Shiga toxin-producing Escherichia coli in asymptomatic nursery children in Lower Saxony (Germany), 2014." Epidemiology and Infection 144, no. 16 (September 9, 2016): 3540–48. http://dx.doi.org/10.1017/s0950268816001837.

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SUMMARYChildren may be at higher risk for carriage of antimicrobial-resistant bacteria because of higher usage of antimicrobials. They also have higher rates of Shiga toxin-producing Escherichia coli (STEC) infections than other population groups. Some infections, particularly in children, are asymptomatic, but still lead to the excretion of large numbers of bacteria and viruses that may cause clinical disease in other individuals. That is one reason why, in Lower Saxony as in other German federal states – asymptomatic carriers of STEC are excluded from nurseries and schools until three consecutive stool samples test negative in order to prevent secondary cases. The prevalence of children who are asymptomatic STEC carriers is unknown. But if it is high, this measure would have substantial socioeconomic effects on families. Infections with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are an increasing problem for public health, especially for hospitals. However, there are no reliable estimates of the prevalence of asymptomatic ESBL-E carriers in Lower Saxony, as there is no mandatory requirement to report these carriers. In order to discuss the exclusion policies for children attending nurseries and ascertain a baseline of ESBL-E carriers, we conducted a cross-sectional study. The aim was to determine the prevalence of ESBL-E and STEC and identify risk factors for carriage in nursery children without diarrhoea (asymptomatic) aged 0–6 years in four selected districts in Northern Germany. During April–September 2014, we collected stool specimens with the support of voluntarily participating nurseries. We tested for STEC by PCR and for ESBL-E on chromogenic agar. Questionnaires answered by parents contained data on eating and drinking habits, outdoor activities, prior antibiotic treatment and animal contact for each participating child. We compared the epidemiological characteristics of ESBL-E carriers vs. non-carriers by using univariable analysis (P value, odds ratio and 95% confidence interval). We could not perform a statistical analysis for STEC carriers due to the low numbers of positive STEC specimens. Of 224 asymptomatic nursery children, we found a prevalence of 2·3% for ESBL-E carriage and 0·5% for STEC carriage. Asymptomatic ESBL-E carriers were more likely to have consumed raw milk, have had contact with pet rodents, or to have taken antibiotics during the preceding 6 months. We also found a high proportion of raw milk consumption (11%). We suggest that the low STEC prevalence in asymptomatic children supports the current practice of excluding STEC carriers from nurseries. The association between ESBL-E carriage and raw milk consumption and contact with pet rodents needs further investigation.

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Bratcher, Holly B., Charlene M. C. Rodrigues, Adam Finn, Mandy Wootton, J. Claire Cameron, Andrew Smith, Paul Heath, et al. "UKMenCar4: A cross-sectional survey of asymptomatic meningococcal carriage amongst UK adolescents at a period of low invasive meningococcal disease incidence." Wellcome Open Research 4 (August 6, 2019): 118. http://dx.doi.org/10.12688/wellcomeopenres.15362.1.

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Carriage of Neisseria meningitidis, the meningococcus, is a prerequisite for invasive meningococcal disease (IMD), a potentially devastating infection that disproportionately afflicts infants and children. Humans are the sole known reservoir for the meningococcus, and it is carried asymptomatically in the nasopharynx of ~10% of the population. Rates of carriage are dependent on age of the host and social and behavioural factors. In the UK, meningococcal carriage has been studied through large, multi-centre carriage surveys of adolescents in 1999, 2000, and 2001, demonstrating carriage can be affected by immunisation with the capsular group C meningococcal conjugate vaccine, inducing population immunity against carriage. Fifteen years after these surveys were carried out, invasive meningococcal disease incidence had declined from a peak in 1999. The UKMenCar4 study was conducted in 2014/15 to investigate rates of carriage amongst the adolescent population during a period of low disease incidence. The protocols and methodology used to perform UKMenCar4, a large carriage survey, are described here.

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Bratcher, Holly B., Charlene M. C. Rodrigues, Adam Finn, Mandy Wootton, J. Claire Cameron, Andrew Smith, Paul Heath, et al. "UKMenCar4: A cross-sectional survey of asymptomatic meningococcal carriage amongst UK adolescents at a period of low invasive meningococcal disease incidence." Wellcome Open Research 4 (October 28, 2019): 118. http://dx.doi.org/10.12688/wellcomeopenres.15362.2.

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Carriage of Neisseria meningitidis, the meningococcus, is a prerequisite for invasive meningococcal disease (IMD), a potentially devastating infection that disproportionately afflicts infants and children. Humans are the sole known reservoir for the meningococcus, and it is carried asymptomatically in the nasopharynx of ~10% of the population. Rates of carriage are dependent on age of the host and social and behavioural factors. In the UK, meningococcal carriage has been studied through large, multi-centre carriage surveys of adolescents in 1999, 2000, and 2001, demonstrating carriage can be affected by immunisation with the capsular group C meningococcal conjugate vaccine, inducing population immunity against carriage. Fifteen years after these surveys were carried out, invasive meningococcal disease incidence had declined from a peak in 1999. The UKMenCar4 study was conducted in 2014/15 to investigate rates of carriage amongst the adolescent population during a period of low disease incidence. The protocols and methodology used to perform UKMenCar4, a large carriage survey, are described here.

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Olier, Maïwenn, Fabrice Pierre, Sandrine Rousseaux, Jean-Paul Lemaître, André Rousset, Pascal Piveteau, and Jean Guzzo. "Expression of Truncated Internalin A Is Involved in Impaired Internalization of Some Listeria monocytogenes Isolates Carried Asymptomatically by Humans." Infection and Immunity 71, no. 3 (March 2003): 1217–24. http://dx.doi.org/10.1128/iai.71.3.1217-1224.2003.

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ABSTRACT Fourteen human carriage Listeria monocytogenes isolates were compared to sporadic and epidemic-associated human strains in order to ascertain the pathogenic behavior of these unrecognized asymptomatic strains. Experimental infection of 14-day-old chick embryos revealed that the majority of the carriage strains were attenuated for virulence. Of the 10 attenuated carriage strains, 5 were affected in their invasion capacities in vitro. Western blot analysis with antibody directed against InlA, the surface protein implicated in the internalization in host cells, allowed correlation between the ability of the carriage strains to enter Caco-2 cells and InlA expression. Indeed, these five carriage strains produced truncated forms of InlA. Four of the five truncated forms of InlA had an apparent molecular mass of 47 kDa. In order to assess the existence of a genetic lineage, partial sequences of inlA gene of these four strains were compared and revealed that they had a high degree of sequence conservation at the gene (99.86%) and amino acid (100%) levels. Comparison of their nucleotide sequences with that of the corresponding segment of inlA from EGD-e and Scott A strains, taken as epidemic references, showed more divergence. Taken together, these observations suggest the presence of specific traits that characterize L. monocytogenes strains isolated during asymptomatic carriage. Some of these traits could provide some explanations about the determinants that make them unable to cause systemic human infection.

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Flores, Anthony R., Brittany E. Jewell, Randall J. Olsen, Samuel A. Shelburne, Nahuel Fittipaldi, Stephen B. Beres, and James M. Musser. "Asymptomatic Carriage of Group A Streptococcus Is Associated with Elimination of Capsule Production." Infection and Immunity 82, no. 9 (July 14, 2014): 3958–67. http://dx.doi.org/10.1128/iai.01788-14.

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ABSTRACTHumans commonly carry pathogenic bacteria asymptomatically, but despite decades of study, the underlying molecular contributors remain poorly understood. Here, we show that a group A streptococcus carriage strain contains a frameshift mutation in thehasAgene resulting in loss of hyaluronic acid capsule biosynthesis. This mutation was repaired by allelic replacement, resulting in restoration of capsule production in the isogenic derivative strain. The “repaired” isogenic strain was significantly more virulent than the carriage strain in a mouse model of necrotizing fasciitis and had enhanced growthex vivoin human blood. Importantly, the repaired isogenic strain colonized the mouse oropharynx with significantly greater bacterial burden and had significantly reduced ability to internalize into cultured epithelial cells than the acapsular carriage strain. We conducted full-genome sequencing of 81 strains cultured serially from 19 epidemiologically unrelated human subjects and discovered the common theme that mutations negatively affecting capsule biosynthesis arisein vivoin thehasoperon. The significantly decreased capsule production is a key factor contributing to the molecular détente between pathogen and host. Our discoveries suggest a general model for bacterial pathogens in which mutations that downregulate or ablate virulence factor production contribute to carriage.

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Alasmari, F., S. M. Seiler, T. Hink, C. A. D. Burnham, and E. R. Dubberke. "Prevalence and Risk Factors for Asymptomatic Clostridium difficile Carriage." Clinical Infectious Diseases 59, no. 2 (April 21, 2014): 216–22. http://dx.doi.org/10.1093/cid/ciu258.

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Golubchik, Tanya, Elizabeth M. Batty, Ruth R. Miller, Helen Farr, Bernadette C. Young, Hanna Larner-Svensson, Rowena Fung, et al. "Within-Host Evolution of Staphylococcus aureus during Asymptomatic Carriage." PLoS ONE 8, no. 5 (May 1, 2013): e61319. http://dx.doi.org/10.1371/journal.pone.0061319.

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Gentile, G., A. Caprioli, G. Donelli, M. Venditti, F. Mandelli, and P. Martino. "Asymptomatic carriage of Cryptosporidium in two patients with leukemia." American Journal of Infection Control 18, no. 2 (April 1990): 127–28. http://dx.doi.org/10.1016/0196-6553(90)90092-7.

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Guerrero, D. M., J. C. Becker, E. C. Eckstein, S. Kundrapu, A. Deshpande, A. K. Sethi, and C. J. Donskey. "Asymptomatic carriage of toxigenic Clostridium difficile by hospitalized patients." Journal of Hospital Infection 85, no. 2 (October 2013): 155–58. http://dx.doi.org/10.1016/j.jhin.2013.07.002.

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Ilkit, Macit, and Hakan Demirhindi. "Asymptomatic dermatophyte scalp carriage: laboratory diagnosis, epidemiology and management." Mycopathologia 165, no. 2 (November 23, 2007): 61–71. http://dx.doi.org/10.1007/s11046-007-9081-0.

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Küçükgöz-Güleç, Ümran, Ramazan Gümral, Ahmet B. Güzel, Ghanim Khatib, Mehmet Karakaş, and Macit Ilkit. "Asymptomatic groin dermatophyte carriage detected during routine gynaecologic examinations." Mycoses 56, no. 3 (September 24, 2012): 250–55. http://dx.doi.org/10.1111/myc.12012.

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Schindler, Yulia, Galia Rahav, Israel Nissan, Liora Madar-Shapiro, Julia Abtibol, Moti Ravid, and Yasmin Maor. "Group B Streptococcus serotypes associated with different clinical syndromes: Asymptomatic carriage in pregnant women, intrauterine fetal death, and early onset disease in the newborn." PLOS ONE 15, no. 12 (December 31, 2020): e0244450. http://dx.doi.org/10.1371/journal.pone.0244450.

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Objectives To study Group B Streptococcus (GBS) isolates associated with different clinical syndromes: asymptomatic carriage in pregnant women, intrauterine fetal death (IUFD), and early onset disease (EOD) in the newborn. Methods GBS isolates were collected from asymptomatic pregnant women admitted for labor, IUFD cases, and neonates with EOD. Serotypes and antibiotic susceptibilities were determined. Multilocus sequence typing (MLST) was performed to assess genetic epidemiology. Results GBS carriage rate was 26.1% (280/1074). The dominant serotype among asymptomatic pregnant women was VI [98/240 women (40.8%)], followed by serotypes III, V and IV in 42/240 (17.5%), 30/240 (12.5%) and 28/240 (11.7%) women, respectively. The dominant serotype in IUFD cases was serotype VI [10/13 (76.9%)]. In contrast the prevalent serotype among EOD cases was III [16/19 (84.2%)]. ST-1 was associated with IUFD [7/13 (53.8%)], ST-17 was associated with serotype III and EOD in the newborn 14/19 (73.7%)]. Erythromycin and clindamycin resistance reached 36.8%, 7.7% and 20.0%among EOD, vaginal carriage and IUFD, respectively. Conclusions Serotypes VI and ST-1 were dominant among asymptomatic pregnant women and in IUFD cases while EOD was associated with serotype III and ST-17. Invasive mechanisms thus may differ between IUFD and EOD in the newborn and virulence may be related to capsule serotype. Resistance rates to erythromycin and clindamycin were high in EOD cases.

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Donskey, Curtis J., Venkata C. K. Sunkesula, Nimalie D. Stone, Carolyn V. Gould, L. Clifford McDonald, Matthew Samore, JeanMarie Mayer, et al. "Transmission ofClostridium difficilefrom asymptomatically colonized or infected long-term care facility residents." Infection Control & Hospital Epidemiology 39, no. 8 (May 31, 2018): 909–16. http://dx.doi.org/10.1017/ice.2018.106.

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AbstractObjectiveTo test the hypothesis that long-term care facility (LTCF) residents withClostridium difficileinfection (CDI) or asymptomatic carriage of toxigenic strains are an important source of transmission in the LTCF and in the hospital during acute-care admissions.DesignA 6-month cohort study with identification of transmission events was conducted based on tracking of patient movement combined with restriction endonuclease analysis (REA) and whole-genome sequencing (WGS).SettingVeterans Affairs hospital and affiliated LTCF.ParticipantsThe study included 29 LTCF residents identified as asymptomatic carriers of toxigenicC. difficilebased on every other week perirectal screening and 37 healthcare facility-associated CDI cases (ie, diagnosis >3 days after admission or within 4 weeks of discharge to the community), including 26 hospital-associated and 11 LTCF-associated cases.ResultsOf the 37 CDI cases, 7 (18·9%) were linked to LTCF residents with LTCF-associated CDI or asymptomatic carriage, including 3 of 26 hospital-associated CDI cases (11·5%) and 4 of 11 LTCF-associated cases (36·4%). Of the 7 transmissions linked to LTCF residents, 5 (71·4%) were linked to asymptomatic carriers versus 2 (28·6%) to CDI cases, and all involved transmission of epidemic BI/NAP1/027 strains. No incident hospital-associated CDI cases were linked to other hospital-associated CDI cases.ConclusionsOur findings suggest that LTCF residents with asymptomatic carriage ofC. difficileor CDI contribute to transmission both in the LTCF and in the affiliated hospital during acute-care admissions. Greater emphasis on infection control measures and antimicrobial stewardship in LTCFs is needed, and these efforts should focus on LTCF residents during hospital admissions.

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Kutty, Preeta K., Susan E. Beekmann, Ronda L. Sinkowitz-Cochran, Erik R. Dubberke, David T. Kuhar, L. Clifford McDonald, and Philip M. Polgreen. "A national survey of testing and management of asymptomatic carriage of C. difficile." Infection Control & Hospital Epidemiology 40, no. 7 (May 20, 2019): 801–3. http://dx.doi.org/10.1017/ice.2019.109.

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AbstractA nationwide survey indicated that screening for asymptomatic carriers of C. difficile is an uncommon practice in US healthcare settings. Better understanding of the role of asymptomatic carriage in C. difficile transmission, and of the measures available to reduce that risk, are needed to inform best practices regarding the management of carriers.

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Espiritu, Katrina, Michael Vernon, Donna Schora, Lance Peterson, and Kamaljit Singh. "972. Asymptomatic Carriage of Clostridiodes difficile and Risk of Subsequent Infection." Open Forum Infectious Diseases 5, suppl_1 (November 2018): S38. http://dx.doi.org/10.1093/ofid/ofy209.088.

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Abstract Background C. difficile is one of the most common healthcare-associated infections in the United States. Studies of patients with asymptomatic carriage of toxigenic C. difficile have reported conflicting results on the risk of subsequent C. difficile infection (CDI). Older studies suggest that the risk was low and colonization may be protective. Subsequent studies indicate that asymptomatic carriers have a 6-fold greater risk of developing CDI. The aims of our study were to assess the burden of asymptomatic C. difficile carriage and risk of subsequent CDI. Methods Adult inpatients at NorthShore University HealthSystem, Illinois hospitals between August 1, 2017 and February 28, 2018 were eligible for the study. Focused admission screening of patients at high risk of C. difficile carriage was performed: (1) history of CDI or colonization, (2) prior hospitalization past 2 months, or (3) admission from a long-term care facility. A rectal swab was collected and tested using the cobas® Cdif Test (Roche) real-time PCR. The development of hospital onset CDI (HO-CDI) in colonized patients was monitored prospectively for at least 2 months. HO-CDI testing of colonized patients was performed using the Cepheid GeneXpert RT-PCR. HO-CDI was defined as patients hospitalized for at least 72 hours with 3 or more episodes of diarrhea/24 hours, in the absence of other potential causes of diarrhea. Patient demographics were collected using a standardized form and data analyzed using VassarStats. Results There were 6,104 patients enrolled in the study and 528 (8.7%) were positive on admission for toxigenic C. difficile carriage. The mean age of colonized patients was 75.5 years (range 24–103) and 56.4% (298 patients) were females. Of 528 colonized patients, 21 (4%) had a positive CDI test. A total of 7 patients (1.3%) developed HO-CDI. Mean time to positive HO-CDI was 46.1 days (range 5–120 days). Of 5,576 patients that were negative for C difficile carriage on admission, 14 (0.3%) patients developed HO-CDI. The relative risk of HO-CDI was 5.28 (95% CI: 2.14–13.03, P = 0.05). Conclusion We found that 8.7% of at-risk admissions were asymptomatic toxigenic C. difficile carriers. While only 1.3% developed HO-CDI, asymptomatic carriers had a 5 times higher risk of subsequent CDI compared with non-carriers. Disclosures All authors: No reported disclosures.

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Costa, Carolina Rodrigues, Ana Joaquina Cohen, Orionalda Fátima Lisboa Fernandes, Karla Carvalho Miranda, Xisto Sena Passos, Lúcia Kioko Hasimoto Souza, and Maria do Rosário Rodrigues Silva. "Asymptomatic oral carriage of Candida species in HIV-infected patients in the highly active antiretroviral therapy era." Revista do Instituto de Medicina Tropical de São Paulo 48, no. 5 (October 2006): 257–61. http://dx.doi.org/10.1590/s0036-46652006000500004.

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Oropharyngeal candidiasis is the most common opportunistic fungal infection in individuals infected with human immunodeficiency virus. CD4+ lymphocytes count and the quantification of viral RNA in blood plasma have been found to be the main markers of HIV disease progression. The present study was conducted to evaluate Candida sp. diversity in the oral cavity of HIV-infected patients and to determine whether there was association of CD4+ cell count and viral load with asymptomatic oral Candida carriage. Out of 99 HIV-positive patients studied, 62 (62.6%) had positive culture for Candida (oral carriage) and 37 patients (37.4%) had Candida negative culture (no oral carriage). The etiologic agents most common were C. albicans and C. tropicalis. The range of CD4+ was 6-2305 cells/mm³ in colonized patients and 3-839 cells/mm³ for non-colonized patients, while the viral load was 60-90016 copies/mL for colonized patients and 75-110488 copies/mL for non colonized patients. The viral load was undetectable in 15 colonized patients and in 12 non colonized patients. Our results showed that there was no significant difference of the variables CD4+ cell count and viral load between oral candida carriage and no oral candida carriage patients.

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Osinupebi, Olubunmi A. "Carriage of Hepatitis B Virus and Risk Factors among Health Care Workers in Ogun State." Pan African Journal of Life Sciences 6, no. 1 (March 31, 2022): 378–85. http://dx.doi.org/10.36108/pajols/2202/60.0120.

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Background: Health-care workers (HCWs) are often exposed to potentially infectious body fluids-carrying Hepatitis B virus (HBV) from their workplaces. Typically, most asymptomatic HBV carriers-status may remain unnoticed for decades, despite a few percentages of them with vaccination history. In this study, we aimed at investigating asymptomatic carriage of HBV and its associated risk factors among co-health workers ultimately impacting on patients. Methods: Venous blood samples and demographic data were obtained from a cross sectional survey of HCWs categories working in OOUTH, a referral teaching hospital and other selected health facilities in Ogun state. Immuno-chromatographic discs and Enzyme Linked Immuno-Sorbent assay (ELISA) techniques were adopted for the determination and confirmation of the presence of HBsAg, anti-HBs and total anti-HBc in sera. A structured questionnaire was used for obtaining demographic data which were analyzed by regression analytical technique. Results: About 11.44% (43) of the 376 healthcare workers (HCWs), were infected with HBV. The serological marker of viral particles identified in this positive study population included Hepatitis B envelope antigen (53.49%), Hepatitis Core antigen (13.15%), Hepatitis B surface antibodies (3.99%); and Hepatitis B core antibodies (0.80%). A significant association existed between risk factors such as recapping of used needles and carriage of HBV among the HCWs (p-value =0.017). Conclusion: The carriage rate (11.44%) of HBV among HCWs in Ogun state referral health facilities as against the 8% set standard by W.H.O. in 2009, depict the associated risk factors of asymptomatic carriage, pathogenesis and dissemination in and outside of the health facilities.

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Deji-Agboola, AM, OR Olaosebikan, E. Adenipekun, OA Osinupebi, and FA Olajubu. "Extended Spectrum Beta-Lactamases (ESBLs)-producing Escherichia coli and Klebsiella pneumoniae among asymptomatic Out-patients in a University Health Centre." Annals of Health Research 6, no. 2 (May 17, 2020): 133–42. http://dx.doi.org/10.30442/ahr.0602-02-75.

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Background: Asymptomatic carriage and spread of Extended-Spectrum Beta-Lactamase (ESBLs)-producing Enterobacteriaceae in the community are potential risk factors for transmission of infection. Objective: To determine the prevalence of ESBL resistant genes in Escherichia coli and Klebsiella pneumoniae isolated from asymptomatic out-patients. Methods: Using a questionnaire, demographic information, medical history, previous hospitalization and antibiotics used were obtained. Stool and urine samples were collected from 350 participants, cultured, and the susceptibility of the isolates to antibiotics and ESBL production were determined using the disk diffusion method. ESBL genes such as blaTEM, blaCTX, and blaSHV were identified using the Polymerase Chain Reaction. Results: Escherichia coli and Klebsiella pnuemoniae were identified from the stool samples (256; 69.9% and 89; 24.4% respectively) and urine samples (15; 4.1% and 6; 1.6% respectively). The isolates were susceptible to imipenem (330; 90.6%) and nitrofurantoin (307; 80.4%), most of the isolates were resistant to fluoroquinolones, cephalosporins, and aminoglycosides while all the isolates were resistant to ampicillin. The prevalence of ESBL was 29 (8.3%) and was observed in Escherichia coli (19; 7.0%) and Klebsiella pneumoniae (11; 12.0%), including a dual carriage. The ESBL carriers were resistant to the cephalosporins, fluoroquinolones and aminoglycosides. CTX-M (20; 66.7%), TEM (14; 46.7%), CTX-M and TEM genes co-existed in 9 (30.0%) while no SHV gene was detected in the isolates. Age, sex, prior hospitalization and antibiotics use did not predispose to ESBL carriage. Conclusion: Asymptomatic carriage of ESBL producing enterobacteria in the participants indicates that they can serve as a reservoir of the gene encoding for antibiotic resistance.

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Niang, Makhtar, Cheikh Talla, Nafissatou Diagne, Fatoutama Diene-Sarr, and Cheikh Sokhna. "PO 8419 SPATIO-TEMPORAL MAPPING OF ASYMPTOMATIC AND CLINICAL MALARIA INFECTIONS REVEALS FOCI OF MALARIA TRANSMISSION FOR TARGETED CONTROL INTERVENTIONS." BMJ Global Health 4, Suppl 3 (April 2019): A35.2—A35. http://dx.doi.org/10.1136/bmjgh-2019-edc.91.

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BackgroundThe global decline of malaria incidence over the past decade has led to the thought that elimination could be achieved. This has resulted in an increased interest to design strategies to target the hidden reservoir of asymptomatic infections among populations and interrupt on-going residual local malaria transmission. This study explored the reservoir of asymptomatic Plasmodium infections and its relationship with subsequent clinical malaria infections in low-transmission areas in Senegal.MethodsCross-sectional surveys were carried out in 2013, 2014, 2015, and 2016 and combined with longitudinal follow-up to determine and geolocalise both asymptomatic and clinical malaria episodes in Dielmo and Ndiop, Senegal. The prevalence of asymptomatic Plasmodium carriage in the community was investigated by real-time PCR while clinical malaria attacks were identified at health facilities during the transmission season. All households were georeferenced to spatially map asymptomatic and clinical infections.ResultsThe study revealed substantial asymptomatic infections with average parasite carriage of 8.11% and 7% in Dielmo and Ndiop, respectively. P. falciparum accounted for most asymptomatic infections (more than 90%). In Dielmo, 95% of asymptomatic infections clustered within the same geographical areas while infections were disparate in Ndiop. Preliminary fine-scale mapping of asymptomatic and clinical malaria infections identified clusters of higher malaria incidence interpreted as foci of transmission across the four-year study period with 95%–98% of clinical infections occurring in households where an asymptomatic malaria infection existed.ConclusionThis study revealed substantial asymptomatic Plasmodium infections in both settings throughout the four-year study period and spatial clusters of malaria infections at the microepidemiological level. Together, these findings could offer a feasible approach for a rational targeting of malaria control interventions to achieve elimination.

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COEN, P. G., P. T. HEATH, M. L. BARBOUR, and G. P. GARNETT. "Mathematical models of Haemophilus influenzae type b." Epidemiology and Infection 120, no. 3 (June 1998): 281–95. http://dx.doi.org/10.1017/s0950268898008784.

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A review of empirical studies and the development of a simple theoretical framework are used to explore the relationship between Haemophilus influenzae type b (Hib) carriage and disease within populations. The models emphasize the distinction between asymptomatic and symptomatic infection. Maximum likelihood methods are used to estimate parameter values of the models and to evaluate whether models of infection and disease are satisfactory. The low incidence of carriage suggests that persistence of infection is only compatible with the absence of acquired immunity to asymptomatic infection. The slight decline in carriage rates amongst adults is compatible with acquired immunity, but could be a consequence of reduced contacts. The low rate of disease observed in adulthood cannot be explained if protection from disease is a product of previous detectable exposure to Hib alone. We estimate an Ro of 3·3 for Hib in developed countries, which suggests that current immunization programmes may eliminate the infection. Analysis of the disease data set suggests the absence of maternal immunity and increased susceptibility to disease in the oldest age classes.

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Sandala, Jenna L., Bradley W. Eichar, Laura G. Kuo, Mark M. Hahn, Akash K. Basak, William M. Huggins, Katherine Woolard, Christian Melander, and John S. Gunn. "A dual-therapy approach for the treatment of biofilm-mediated Salmonella gallbladder carriage." PLOS Pathogens 16, no. 12 (December 28, 2020): e1009192. http://dx.doi.org/10.1371/journal.ppat.1009192.

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Asymptomatic carriage of Salmonella Typhi continues to facilitate the transmission of typhoid fever, resulting in 14 million new infections and 136,000 fatalities each year. Asymptomatic chronic carriage of S. Typhi is facilitated by the formation of biofilms on gallstones that protect the bacteria from environmental insults and immune system clearance. Here, we identified two unique small molecules capable of both inhibiting Salmonella biofilm growth and disrupting pre-formed biofilm structures without affecting bacterial viability. In a mouse model of chronic gallbladder Salmonella carriage, treatment with either compound reduced bacterial burden in the gallbladder by 1–2 logs resulting in bacterial dissemination to peripheral organs that was associated with increased mortality. Co-administration of either compound with ciprofloxacin not only enhanced compound efficacy in the gallbladder by a further 1–1.5 logs for a total of 3–4.5 log reduction, but also prevented bacterial dissemination to peripheral organs. These data suggest a dual-therapy approach targeting both biofilm and planktonic populations can be further developed as a safe and efficient treatment of biofilm-mediated chronic S. Typhi infections.

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Caugant, D. A., E. A. Høiby, P. Magnus, O. Scheel, T. Hoel, G. Bjune, E. Wedege, J. Eng, and L. O. Frøholm. "Asymptomatic carriage of Neisseria meningitidis in a randomly sampled population." Journal of Clinical Microbiology 32, no. 2 (1994): 323–30. http://dx.doi.org/10.1128/jcm.32.2.323-330.1994.

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Ilkit, Macit, Hakan Demirhindi, Mesut Yetgin, Aylin Ates, Aygül Turaç-Biçer, and Erkan Yula. "Asymptomatic dermatophyte scalp carriage in school children in Adana, Turkey." Mycoses 50, no. 2 (March 2007): 130–34. http://dx.doi.org/10.1111/j.1439-0507.2006.01335.x.

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Ramoni, Stefano, Carlo Alberto Maronese, Nicole Morini, Gianluca Avallone, Eleonora Quattri, Carlo Giovanni Carrera, Francesca Laura Boggio, and Angelo Valerio Marzano. "Syphilis and monkeypox co-infection: Coincidence, synergy or asymptomatic carriage?" Travel Medicine and Infectious Disease 50 (November 2022): 102447. http://dx.doi.org/10.1016/j.tmaid.2022.102447.

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Noubouossie, D., C. T. Tagny, A. Same-Ekobo, and D. Mbanya. "Asymptomatic carriage of malaria parasites in blood donors in Yaoundé." Transfusion Medicine 22, no. 1 (December 5, 2011): 63–67. http://dx.doi.org/10.1111/j.1365-3148.2011.01121.x.

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PETTOELLO-MANTOVANI, MASSIMO, LUCIO DI MARTINO, GIUSEPPE DETTORI, PIETRO VAJRO, SILVESTRO SCOTTI, MARIA TERESA DITULLIO, and STEFANO GUANDALINI. "Asymptomatic carriage of intestinal Cryptosporidium in immunocompetent and immunodeficient children." Pediatric Infectious Disease Journal 14, no. 12 (December 1995): 1042–46. http://dx.doi.org/10.1097/00006454-199512000-00003.

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Brunton, L. A., J. S. Knapp, J. Heritage, and H. M. Miller. "Asymptomatic carriage of Clostridium difficile PCR ribotype 078 in pigs." Advances in Animal Biosciences 1, no. 1 (April 2010): 118. http://dx.doi.org/10.1017/s204047001000261x.

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Peach, S. L., S. P. Borriello, H. Gaya, F. E. Barclay, and A. R. Welch. "Asymptomatic carriage of Clostridium difficile in patients with cystic fibrosis." Journal of Clinical Pathology 39, no. 9 (September 1, 1986): 1013–18. http://dx.doi.org/10.1136/jcp.39.9.1013.

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Wakefield, Ann E., Austin R. Lindley, Helen E. Ambrose, Cecile‐Marie Denis, and Robert F. Miller. "Limited Asymptomatic Carriage ofPneumocystis jiroveciin Human Immunodeficiency Virus–Infected Patients." Journal of Infectious Diseases 187, no. 6 (March 15, 2003): 901–8. http://dx.doi.org/10.1086/368165.

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Taylor, Walter R. J. "Assessing Gametocyte Carriage in Treated Asymptomatic Falciparum Carriers in Africa." EBioMedicine 14 (December 2016): 5–6. http://dx.doi.org/10.1016/j.ebiom.2016.11.018.

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Devaraj, Aishwarya, Juan F. González, Bradley Eichar, Gatan Thilliez, Robert A. Kingsley, Stephen Baker, Marc W. Allard, Lauren O. Bakaletz, John S. Gunn, and Steven D. Goodman. "Enhanced biofilm and extracellular matrix production by chronic carriage versus acute isolates of Salmonella Typhi." PLOS Pathogens 17, no. 1 (January 19, 2021): e1009209. http://dx.doi.org/10.1371/journal.ppat.1009209.

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Salmonella Typhi is the primary causative agent of typhoid fever; an acute systemic infection that leads to chronic carriage in 3–5% of individuals. Chronic carriers are asymptomatic, difficult to treat and serve as reservoirs for typhoid outbreaks. Understanding the factors that contribute to chronic carriage is key to development of novel therapies to effectively resolve typhoid fever. Herein, although we observed no distinct clustering of chronic carriage isolates via phylogenetic analysis, we demonstrated that chronic isolates were phenotypically distinct from acute infection isolates. Chronic carriage isolates formed significantly thicker biofilms with greater biomass that correlated with significantly higher relative levels of extracellular DNA (eDNA) and DNABII proteins than biofilms formed by acute infection isolates. Importantly, extracellular DNABII proteins include integration host factor (IHF) and histone-like protein (HU) that are critical to the structural integrity of bacterial biofilms. In this study, we demonstrated that the biofilm formed by a chronic carriage isolate in vitro, was susceptible to disruption by a specific antibody against DNABII proteins, a successful first step in the development of a therapeutic to resolve chronic carriage.

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Salvador, Fernando, Beatriz Lobo, Lidia Goterris, Carmen Alonso-Cotoner, Javier Santos, Elena Sulleiro, Begoña Bailo, et al. "Blastocystis sp. Carriage and Irritable Bowel Syndrome: Is the Association Already Established?" Biology 10, no. 4 (April 19, 2021): 340. http://dx.doi.org/10.3390/biology10040340.

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Background: The aim of the present study is to describe the occurrence of Blastocystis sp. detection among asymptomatic subjects and patients with irritable bowel syndrome in order to evaluate the potential association between irritable bowel syndrome and the parasitic infection. Methods: Cross-sectional study where adult patients with irritable bowel syndrome diagnosed according to Rome IV criteria were included. A control group was formed by asymptomatic subjects older than 18 years. Exclusion criteria were: immunosuppressive condition or having received any drug with demonstrated activity against Blastocystis sp. within the last 6 months before study inclusion. Epidemiological and clinical information was collected from all included participants. Two stool samples were obtained from all participants: one sample for microscopic examination and one sample for Blastocystis sp. PCR detection. Blastocystis sp. infection was defined by the positivity of any of the diagnostic techniques. Results: Seventy-two participants were included (36 asymptomatic subjects and 36 patients with irritable bowel syndrome). Thirty-five (48.6%) were men, and median age of participants was 34 (IQR 29–49) years. The overall rate of Blastocystis sp. carriage was 27.8% (20/72). The prevalence assessed through microscopic examination was 22.2% (16/72), while the prevalence measured by PCR was 15.3% (11/72). When comparing the presence of Blastocystis sp. between asymptomatic subjects and IBS patients, we did not find any statistically significant difference (36.1% vs. 19.4% respectively, p = 0.114). Conclusions: regarding the occurrence of Blastocystis sp., no differences were found between asymptomatic participants and patients with irritable bowel disease irrespective of the diagnostic technique performed.

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Maiden, Martin C. J., Ana Belén Ibarz-Pavón, Rachel Urwin, Stephen J. Gray, Nicholas J. Andrews, Stuart C. Clarke, A. Mark Walker, et al. "Impact of Meningococcal Serogroup C Conjugate Vaccines on Carriage and Herd Immunity." Journal of Infectious Diseases 197, no. 5 (March 1, 2008): 737–43. http://dx.doi.org/10.1086/527401.

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AbstractBackground. In 1999, meningococcal serogroup C conjugate (MCC) vaccines were introduced in the United Kingdom for those under 19 years of age. The impact of this intervention on asymptomatic carriage of meningococci was investigated to establish whether serogroup replacement or protection by herd immunity occurred.Methods. Multicenter surveys of carriage were conducted during vaccine introduction and on 2 successive years, resulting in a total of 48,309 samples, from which 8599 meningococci were isolated and characterized by genotyping and phenotyping.Results. A reduction in serogroup C carriage (rate ratio, 0.19) was observed that lasted at least 2 years with no evidence of serogroup replacement. Vaccine efficacy against carriage was 75%, and vaccination had a disproportionate impact on the carriage of sequence type (ST)-11 complex serogroup C meningococci that (rate ratio, 0.06); these meningococci also exhibited high rates of capsule expression.Conclusions. The impact of vaccination with MCC vaccine on the prevalence of carriage of group C meningococci was consistent with herd immunity. The high impact on the carriage of ST-11 complex serogroup C could be attributed to high levels of capsule expression. High vaccine efficacy against disease in young children, who were not protected long-term by the schedule initially used, is attributed to the high vaccine efficacy against carriage in older age groups.

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Mokhort, Hennadii. "Multiple Linear Regression Model of Meningococcal Disease in Ukraine: 1992–2015." Computational and Mathematical Methods in Medicine 2020 (February 11, 2020): 1–7. http://dx.doi.org/10.1155/2020/5105120.

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Estimating the rates of invasive meningococcal disease (IMD) from epidemiologic data remains critical for making public health decisions. In Ukraine, such estimations have not been performed. We used epidemiological data to develop a national database. These data were used to estimate the population susceptible to IMD and identify the prevalence of asymptomatic carriers of N. meningitidis using simple epidemiological models of meningococcal disease that may be used by the national policy makers. The goal was to create simple, easily understood analysis of patterns of the infection within Ukraine that would capture the major features of the infection dynamics. Studies used nationally reported data during 1992–2015. A logic model identified the prevalence of carriage and the proportion of the population susceptible to IMD as key drivers of IMD incidence. Multiple linear regression models for all ages (total population) and for children ≤14 years old were fit to national-level data. Linear models with the incidence of IMD as an outcome were highly associated with carriage and estimated susceptible population in both total population and children (R2 = 0.994 and R2 = 0.978, respectively). The susceptibility rate to IMD in the study total population averaged 0.0034 ± 0.0009% annually. At the national level, IMD can be characterized by the simple interaction between the prevalence of asymptomatic carriage and the proportion of the susceptible population. IMD association with prevalence rates of carriage and the proportion of susceptible population is sufficiently strong for national-level planning of intervention strategies for IMD.

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Jallad, M. A., R. Naoufal, J. Irani, and E. Azar. "Extended Spectrum Beta-Lactamase Carriage State among Elderly Nursing Home Residents in Beirut." Scientific World Journal 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/987580.

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Introduction.ESBL-producing Enterobacteriaceae can cause severe infections, but they are also isolated from the stool of asymptomatic subjects. Faecal carriage of such organism is poorly understood.Methods.First phase of the study was cross-sectional with prevalence and epidemiology of ESBL faecal carriage in two nursing homes in Beirut: 57 residents in the first (NH1) and 151 residents in the second (NH2). In second phase, faecal swabs from cohort of NH1 residents were examined for carriage at six-week intervals over three-month period. Residents’ charts were reviewed to assess carriage risk factors.Results.Over 3 consecutive samplings at NH1, 81% of residents were at least one-time carriers with 50% at the first round, 60.4% at the second, and 74.5% at the last one. At NH2, 68.2% of residents were carriers. Constipation (in NH1) and antibiotic intake (in NH2) were significantly associated with higher ESBL faecal carriage while the length of stay at the nursing home (in NH2) was associated with less carriage.Conclusion.Faecal carriage of ESBL-producing Enterobacteriaceae is high among nursing home patients in Beirut. The rate of carriage changes rapidly and significantly over time either with multiple factors playing a possible role like outbreak spreading, antibiotic, and health care system exposure.

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Le Saux, Nicole, Fraser Ashton, Maksudar Rahman, Alan Ryan, Edward Ellis, Susan Tamblyn, Joan Morris, et al. "Carriage ofNeisseriaSpecies in Communities with Different Rates of Meningococcal Disease." Canadian Journal of Infectious Diseases 3, no. 2 (1992): 60–64. http://dx.doi.org/10.1155/1992/928727.

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A single clone,Neisseria meningitidisserogroup C (C:2a:P1.2), was isolated from seven patients during a cluster of cases of meningococcal disease in Ontario in 1989. To determine whether the clone was present in asymptomatic individuals in the same population, pharyngeal swabs were taken from 7% (644 of 9125) of residents who were vaccinated during the outbreak. Rates of isolation ofNeisseriaspecies were also compared to those in two other geographical areas which did not have an elevated incidence of meningococcal disease. The rate of carriage ofN meningitidisin the asymptomatic individuals sampled was between 1.9% and 5.4%. The clone isolated from patients was not present among the carrier strains as determined by sero- and subtyping and electrophoretic analysis of metabolic enzymes. Age greater than six years was the only factor associated with colonization withN meningitidis.

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Journal articles on the topic 'Asymptomatic carriage'

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