The effect of human immunodeficiency virus type-1 on the infectiousness of tuberculosis.

ABSTRACT

SETTING: Developing country tertiary referral hospital plus catchment community. OBJECTIVE: To determine the infectiousness of culture-confirmed pulmonary tuberculosis in patients infected with Human Immunodeficiency Virus type-1 (HIV-1). DESIGN: Comparison of the incidence of tuberculosis and the prevalence of tuberculin skin test positivity among the household contacts of both HIV-1 positive and negative cases with pulmonary tuberculosis. RESULTS: Of 255 contacts of HIV-1 negative index cases, 2 were HIV-1 positive and of 102 contacts of HIV-1 positive index cases, 14 were HIV-1 positive (odds ratio (OR) = 20.0 95% Confidence Interval (CI) 4.4-193). 21 cases of tuberculosis were diagnosed among contacts, of whom 3 were HIV-1 positive. The overall unadjusted OR for tuberculosis among contacts of HIV-1 positive index cases was 1.6 (95% CI 0.6-4.3) compared to contacts of HIV-1 negative index cases. Amongst HIV-1 negative contacts alone the OR was 1.5 (95% CI 0.4-4.4). In this group the best predictors of tuberculosis among contacts were female sex of the index case (OR = 3.4 95% CI 1.1-12), sharing the same bed as the index case (OR = 2.6 95% CI 0.9-7.4), and contact's age less than 5 years (OR = 3.3 95% CI 1.1-9.5). HIV-1 positive contacts were more likely to develop tuberculosis than HIV-1 negative contacts (OR = 4.1 95% CI 0.7-17). Tuberculin skin test positivity rates were the same among the HIV-1 negative contacts of HIV-1 positive and negative index cases (OR = 1.1 CI 0.7-1.6). CONCLUSIONS: HIV-1 associated pulmonary tuberculosis is not more infectious than tuberculosis alone. The presence of HIV-1 in a community does not mandate a change in the management of contacts of patients with pulmonary tuberculosis.

ABSTRACT

PIP Using data on tuberculosis (TB) index cases over age 15 years seen at the Infectious Diseases Hospital in Nairobi and the Ngaira Avenue Chest Clinic over September 1, 1989 and October 10, 1990, and their contacts, the authors determined the infectiousness of culture-confirmed pulmonary TB in patients infected with HIV-1. Comparing the incidence of TB and the prevalence of tuberculin skin test positivity among the household contacts of HIV-1 positive and negative cases with pulmonary TB found HIV-1-associated pulmonary TB to be no more infectious than TB alone. The presence of HIV-1 in a community therefore does not require a change in the management of contacts of patients with pulmonary TB.