Prevalence and risk factors associated with tuberculin skin test positivity among household contacts of smear-positive pulmonary tuberculosis cases in Umerkot, Pakistan

S. K. Rathi, S. Akhtar, M. H. Rahbar, S. I. Azam

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40 Citations (Scopus)

Abstract

STUDY POPULATION AND SETTING: Household contacts of acid-fast bacilli (AFB) sputum smear-positive tuberculosis patients in the Umerkot Taluka, Sindh, Pakistan. OBJECTIVE: To estimate the prevalence of and identify risk factors associated with tuberculin skin test (TST) positivity among household contacts of acid-fast bacilli (AFB) sputum smear-positive pulmonary tuberculosis cases. DESIGN: A cross-sectional study of household contacts of AFB sputum smear-positive tuberculosis cases, registered at the Umerkot Anti-Tuberculosis Association clinic from August 1999 to September 1999. The contact's Mycobacterium tuberculosis infection status was assessed using TST. On the day of the TST, a predesigned questionnaire was administered to collect data on putative risk factors for TST positivity among contacts. The data were analysed using a marginal logistic regression model by the method of generalised estimating equations (GEE) to determine risk factors independently associated with TST positivity. RESULTS: The prevalence of TST positivity among household contacts of AFB sputum smear-positive index patients was 49.4%. The final multivariate GEE model showed that contact's age and sleeping site relative to the index case, the intensity of the index case's AFB sputum-smear positivity and the contact's BCG scar status were independent predictors of TST positivity among household contacts of AFB sputum smear-positive index cases. CONCLUSIONS: The results suggest that the household contacts of AFB sputum smear-positive tuberculosis patients in a poor neighbourhood of rural Sindh had a high prevalence of M. tuberculosis infection as determined by TST. Poor housing conditions seem to contribute to the spread of M. tuberculosis infection. Early diagnosis of pulmonary TB through evaluation of TST-positive household contacts, followed by appropriate therapy, may prevent further spread of M. tuberculosis infection. We recommend an awareness programme to prevent household contacts from acquiring M. tuberculosis infection from smear-positive pulmonary TB cases.

Original languageEnglish
Pages (from-to)851-857
Number of pages7
JournalInternational Journal of Tuberculosis and Lung Disease
Volume6
Issue number10
Publication statusPublished - 1 Oct 2002

Keywords

  • Cross-sectional study
  • Household contact
  • Mycobacterium tuberculosis
  • Pakistan
  • Risk factors
  • Tuberculin skin test

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