Rationale: South Africa has a high prevalence of tuberculosis (TB) and HIV-coinfected adults in whom TB is often diagnosed late in the course of disease.
Objectives: Improved case-finding approaches for TB and HIV are needed to reduce mortality and prevent transmission.
Methods: We identified newly diagnosed index TB cases in a rural district and enrolled their households in a TB-HIV contact-tracing study. A group of randomly selected control households were enrolled to determine community prevalence of undetected TB and HIV. Field teams screened participants for TB symptoms, collected sputum specimens for smear microscopy and culture, provided HIV counseling and testing, and collected blood for CD4 testing. Participants were referred to public clinics for TB treatment and antiretroviral therapy.
Measurements and main results: We evaluated 2,843 household contacts of 727 index patients with TB and 983 randomly selected control household members. The prevalence of TB in household contacts was 6,075 per 100,000 (95% confidence interval, 5,789-6,360 per 100,000), whereas the prevalence detected in randomly selected households was 407 per 100,000 (95% confidence interval, 0-912 per 100,000; prevalence difference, 5,668 per 100,000; P < 0.001). TB detected among contacts was less likely to be smear-positive than in the index patients (6% vs. 22%; P < 0.001). Most contacts with culture-confirmed TB were asymptomatic. At least one case of undiagnosed TB was found in 141 (19%) of 727 contact versus 4 (1%) of 312 control households. HIV testing was positive in 166 (11%) of 1,568 contacts tested versus 76 (14%) of 521 control participants tested (odds ratio, 1.48; P = 0.02).
Conclusions: Active case finding in TB contact households should be considered to improve TB and HIV case detection in high-prevalence settings, but sensitive diagnostic tools are necessary.