Free Content Additional risk of developing TB for household members with a TB case at home at intake: a 15-year study

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Abstract:

OBJECTIVE: To assess the additional risk to household contacts from an infectious case of tuberculosis (TB) at home in a rural community in south India.

METHODS: In all, 3506 contacts of smear-positive (S+C+) and 2910 contacts of smear-negative TB cases (S−C+) and 246845 persons with no TB case at home were followed for 15 years, with a repeat survey every 2.5 years consisting of radiographic and sputum examination, selective follow-up of high-risk individuals and passive surveillance. If a case developed during follow-up, all household members were subsequently considered as contacts. Cox's proportional hazards model (multivariate) was employed to compare incidences.

RESULTS: The annual incidence of culture-positive TB was respectively 526 and 271 per 100000 population for contacts of smear-positive and smear-negative patients, and 198/100000 in non-contacts. The adjusted hazard rate was 3.4 for contacts of smear-positive patients (95%CI 3.0–3.9) and 1.7 for contacts of smear-negative patients (95%CI 1.4–2.0) as compared to non-contacts. Of 3942 incident cases, 337 (8.5%) came from households with a TB case.

CONCLUSION: Although family contacts had a significantly higher incidence, their contribution to total new caseload was meagre. Contact chemoprophylaxis as a public health measure would therefore have limited impact on community TB incidence.

Keywords: TB infectivity; chemoprophylaxis; risk to contacts

Document Type: Regular Paper

Affiliations: Tuberculosis Research Centre, Indian Council of Medical Research, Chennai, India

Publication date: March 1, 2007

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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

    Certain IJTLD articles are selected for translation into French, Spanish, Chinese or Russian. They are available on the Union website

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