Molecular, Spatial, and Field Epidemiology Suggesting TB Transmission in Community, Not Hospital, Gaborone, Botswana

Surie, Diya; Fane, Othusitse; Finlay, Alyssa; Matsiri, Ogopotse; Tobias, James L.; Click, Eleanor S.; Modongo, Chawangwa; Zetola, Nicola M.; Moonan, Patrick K.; Oeltmann, John E.

doi:10.3201/eid2303.161183

Cited by 13 publications

(11 citation statements)

References 9 publications

(6 reference statements)

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“…With only a small proportion of tuberculosis resulting from household and close social contact transmission, contact tracing in households or among close contacts is unlikely to have a large effect on the incidence of tuberculosis at a community level. This is supported by empirical studies that identify few epidemiological links between molecularly clustered tuberculosis cases 14 , 15 . Our results suggest that the majority of disease results from infection by a small proportion of people with tuberculosis, often referred to as superspreaders.…”

Section: Discussionmentioning

confidence: 76%

An explanation for the low proportion of tuberculosis that results from transmission between household and known social contacts

McCreesh

White

2018

Sci Rep

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We currently have little idea where Mycobacterium tuberculosis (Mtb) transmission occurs in high incidence settings. Molecular studies suggest that only around 8–19% of transmission to adults occurs within-household, or between known social-contacts. This contrasts with findings from social-contact studies, which show that substantial proportions of contact time occur in households, workplaces and schools. A mathematical model of social-contact behaviour and Mtb transmission was developed, incorporating variation in susceptibility and infectiousness. Three types of contact were simulated: household, repeated (individuals outside household contacted repeatedly with daily-monthly frequency) and non-repeated. The model was parameterised using data from Cape Town, South Africa, on mean and variance in contact numbers and contact durations, by contact type, and fitted to an estimate of overdispersion in numbers of secondary cases (‘superspreading’) in Cape Town. Household, repeated, and non-repeated contacts contributed 36%, 13%, and 51% of contact time, and 13%, 8%, and 79% of disease, respectively. Results suggest contact saturation, exacerbated by long disease durations and superspreading, cause the high proportion of transmission between non-repeated contacts. Household and social-contact tracing is therefore unlikely to reach most tuberculosis cases. A better understanding of transmission locations, and methods to identify superspreaders, are urgently required to improve tuberculosis prevention strategies.

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Section: Discussionmentioning

confidence: 76%

An explanation for the low proportion of tuberculosis that results from transmission between household and known social contacts

McCreesh

White

2018

Sci Rep

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“…The risk of infection depends on the degree of exposure. People with pulmonary or laryngeal TB are most likely to transmit the bacteria as long as they are infectious (in the absence of effective treatment) to people they spend time with every day including family members, friends, coworkers and schoolmates "clusters in space and time" [30][31][32]. Early detection and immediate effective treatment can reduce the infectiousness and infectiousness duration of the TB cases.…”

Section: Discussionmentioning

confidence: 99%

“…Early detection and immediate effective treatment can reduce the infectiousness and infectiousness duration of the TB cases. Reducing crowding conditions and improving the ventilation can also decrease the contact rate, although evidence is limited about the minimum standards of optimal ventilation in closed spaces for preventing TB transmission [32,33].…”

Section: Discussionmentioning

confidence: 99%

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Tuberculosis outbreak among high school students in Novi Pazar, Serbia 2016: a retrospective-cohort study

Stošić

Plavša

Mavroeidi

et al. 2019

J Infect Dev Ctries

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Introduction: Between February and November 2016, 17 tuberculosis (TB) cases were identified among high school students in Novi Pazar, Serbia. The objectives of our study were to describe the outbreak, to identify potential risk factors and to evaluate the applied control measures. Methodology: The outbreak was described by time, person and place. A retrospective cohort study was conducted. Attack rates, unadjusted relative risks (RR) and 95% confidence intervals (CI) were calculated. Multiple log-binomial regression analysis was performed to calculate adjusted RR. Results: Sixteen of the total 17 cases occurred among grade 3 students, AR 5.5%. Previous TB family history, (RR = 5.29; 95% CI = 1.63-17.12), spending time with a known TB case at school (RR = 5.38; 95% CI = 1.48-19.55) and exposure to secondhand smoke (RR = 3.37; 95% CI = 1.11-10.29) were all significantly and independently associated with the occurrence of TB. Conclusions: Delayed diagnosis and reporting resulted in delayed initiation of the contact investigation and non-identification of latent TB cases probably favored the occurrence of this outbreak in a low incidence country. Public health authorities should consider revising the existing guidelines, promoting inter-sectorial collaboration and increasing awareness of public health professionals.

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“…We hypothesized that the strains were probably transmitted through the same source of infection. 25 The MIRU-VNTR loci and drug resistance have been explored in previous studies. For example, the ETRB locus was associated with INH resistance, 26 and the MIRU20 locus was associated with EMB resistance.…”

Section: Discussionmentioning

confidence: 99%

Clustering and recent transmission of <em>Mycobacterium tuberculosis</em> in a Chinese population

Mao

Wang

et al. 2018

IDR

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PurposeThe objectives of the present study were to characterize the clinical isolates prevailing in the northeast of Jiangsu and to investigate the mode of transmission. The study also aimed to explore the extent to which Mycobacterium tuberculosis strains contributed to drug resistance and the possible factors related to the recent transmission.Patients and methodsWe consecutively enrolled 912 culture-confirmed pulmonary tuberculosis (TB) cases from 1 January 2013 to 31 December 2014 in Lianyungang City, which is located in the center of China’s vast ocean area and the northeast of Jiangsu province. Isolates were genotyped using 15-locus mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing. The Hunter–Gaston discrimination index (HGDI) was used to estimate the discriminatory power and diversity of molecular markers.ResultsAmong 741 successfully genotyped isolates, 144 (19.43%) strains formed 46 clusters, while 597 (80.57%) isolates had the unique MIRU pattern. The total HGDI for all 15 loci was 0.999. The average cluster size was 3 (2–13) patients. The estimated proportion of recent transmission was 13.34%. Patients with unfavorable treatment outcomes were infected with clustered strains at a higher proportion than were those with favorable treatment outcomes (adjusted OR: 1.78, 95% CI: 1.14–2.85, P=0.012).ConclusionThe probability of recent TB transmission was relatively low in the study site, while the cases mainly arose from the activation of previous infection. Spatial analysis showed that strains forming larger clusters had the characteristics of regional aggregation.

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Molecular, Spatial, and Field Epidemiology Suggesting TB Transmission in Community, Not Hospital, Gaborone, Botswana

Cited by 13 publications

References 9 publications

An explanation for the low proportion of tuberculosis that results from transmission between household and known social contacts

An explanation for the low proportion of tuberculosis that results from transmission between household and known social contacts

Tuberculosis outbreak among high school students in Novi Pazar, Serbia 2016: a retrospective-cohort study

Clustering and recent transmission of <em>Mycobacterium tuberculosis</em> in a Chinese population

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