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The effect of human immunodeficiency virus type-1 on the infectiousness of tuberculosis
1Kenya Medical Research Institute/Wellcome Trust Collaborative Research Programme.
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.