Differential tuberculin testing in rural populations in Ceylon

Pinto, M. R. M.; Arseculeratne, S. N.; Uragoda, C. G.; Hemawardene, D.M.

doi:10.1016/0041-3879(72)90015-3

Cited by 11 publications

(4 citation statements)

References 12 publications

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“…There is epidemiological evidence from several countries that increasing altitude is associated with decreased rates of TB latent infection [8,9] and morbidity [12,14,15,29]. Even after adjusting these epidemiological analyses for potentially confounding variables, high altitude was associated with decreased rates of TB disease [10,11,13,14] and death [16,17].…”

Section: Discussionmentioning

confidence: 99%

Effects of Ascent to High Altitude on Human Antimycobacterial Immunity

et al. 2013

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BackgroundTuberculosis infection, disease and mortality are all less common at high than low altitude and ascent to high altitude was historically recommended for treatment. The immunological and mycobacterial mechanisms underlying the association between altitude and tuberculosis are unclear. We studied the effects of altitude on mycobacteria and antimycobacterial immunity.MethodsAntimycobacterial immunity was assayed in 15 healthy adults residing at low altitude before and after they ascended to 3400 meters; and in 47 long-term high-altitude residents. Antimycobacterial immunity was assessed as the extent to which participants’ whole blood supported or restricted growth of genetically modified luminescent Bacille Calmette-Guérin (BCG) mycobacteria during 96 hours incubation. We developed a simplified whole blood assay that could be used by a technician in a low-technology setting. We used this to compare mycobacterial growth in participants’ whole blood versus positive-control culture broth and versus negative-control plasma.ResultsMeasurements of mycobacterial luminescence predicted the number of mycobacterial colonies cultured six weeks later. At low altitude, mycobacteria grew in blood at similar rates to positive-control culture broth whereas ascent to high altitude was associated with restriction (p≤0.002) of mycobacterial growth to be 4-times less than in culture broth. At low altitude, mycobacteria grew in blood 25-times more than negative-control plasma whereas ascent to high altitude was associated with restriction (p≤0.01) of mycobacterial growth to be only 6-times more than in plasma. There was no evidence of differences in antimycobacterial immunity at high altitude between people who had recently ascended to high altitude versus long-term high-altitude residents.ConclusionsAn assay of luminescent mycobacterial growth in whole blood was adapted and found to be feasible in low-resource settings. This demonstrated that ascent to or residence at high altitude was associated with decreased mycobacterial growth in whole blood relative to controls, consistent with altitude-related augmentation of antimycobacterial cellular immunity.

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Section: Discussionmentioning

confidence: 99%

Effects of Ascent to High Altitude on Human Antimycobacterial Immunity

et al. 2013

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“…There might be an unknown percentage of students infected by atypical mycobacteria. It has been suggested that nonspecific reactions are more prevalent in tropical and subtropical climates (27) . In a study comprising 226 students in Rio de Janeiro, Madeira and Gontijo (28) reported that 12% of the students presented a skin reaction, ranging from 5 to 9 mm, to PPD-G210.…”

Section: Discussionmentioning

confidence: 99%

Risco de infecção pelo Mycobacterium tuberculosis entre alunos da Faculdade de Medicina da Universidade Federal do Rio de Janeiro

Silva¹,

Cunha²,

Kritski

2004

J. bras. pneumol.

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Introduction:There have been few Latin American studies investigating the fact that the rate of tuberculosis (TB) infection among medical students is higher than the 1.3% rate seen in the population at large.Objective: To describe the cumulative incidence and the relative risk for TB infection among medical students.Method: In 1998, a prospective cohort study was conducted involving medical students at the Universidade Federal do Rio de Janeiro Faculdade de Medicina who tested negative (induration <10 mm) on the tuberculin skin test (TST). Students were tested using the two-step TST method and were retested one year later. The students tested were at two different stages in their training: pre-clinical (no contact with patients) and final year (contact with patients). Information about demographic characteristics, BCG vaccination history, and instances of potential exposure to Mycobacterium tuberculosis were obtained using a standardized questionnaire. Of the 575 students initially enrolled, 72% (414) completed the study. Results:The TSTs of 16 (3.9%) of the 414 students converted, representing a cumulative incidence of 3.9% (95% confidence interval = 1.06 to 12.1). Senior medical students were at an almost fourfold higher risk for M. tuberculosis infection than were those in pre-clinical training. Conclusion:The risk for TST conversion is very high in this population.

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“…Environmental mycobacteria share antigens to a various, but not well-characterised, extent with M. tuberculosis, and thus cross-react to different degrees with tuberculin [156][157][158]. This might be M. bovis BCG or environmental mycobacteria.…”

Section: Test Specificitymentioning

confidence: 99%

Tuberculosis contact investigation in low prevalence countries: a European consensus

Kamphorst²,

et al. 2010

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Contact investigation to identify individuals with tuberculosis and latent infection with Mycobacterium tuberculosis is an important component of tuberculosis control in low tuberculosis incidence countries. This document provides evidence-based and best-practice policy recommendations for contact tracing among high-and medium-priority contacts in a variety of settings. It provides a basis for national guidelines on contact investigation and tuberculosis outbreak management, and should support countries and tuberculosis control managers in evaluating and revising national policies. A review of existing guidelines, a literature search, several meetings and consultation with experts were used to formulate and grade recommendations for action during contact investigation.Available tests to identify individuals with latent infection with M. tuberculosis are designed to identify immune response against mycobacterial antigens and have variable predictive value for the likelihood to develop active tuberculosis in different populations. Contact investigation should therefore be limited to situations with a clear likelihood of transmission or to those with a higher probability of developing active tuberculosis, for instance, young children and immunocompromised persons. A risk assessment-based approach is recommended, where the need to screen contacts is prioritised on the basis of the infectiousness of the index case, intensity of exposure and susceptibility of contacts.

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Differential tuberculin testing in rural populations in Ceylon

Cited by 11 publications

References 12 publications

Effects of Ascent to High Altitude on Human Antimycobacterial Immunity

Effects of Ascent to High Altitude on Human Antimycobacterial Immunity

Risco de infecção pelo Mycobacterium tuberculosis entre alunos da Faculdade de Medicina da Universidade Federal do Rio de Janeiro

Tuberculosis contact investigation in low prevalence countries: a European consensus

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