Recent transmission of tuberculosis in a cohort of HIV-1-infected female sex workers in Nairobi, Kenya

A 3-year (1989-92) prospective study of 587 HIV-positive and 132 HIV-negative commercial sex workers in Nairobi Kenya revealed substantial recent transmission of tuberculosis in the HIV-infected group. The cohort was enrolled at a community clinic that provides counseling sexually transmitted disease services and free condoms. In HIV-positive women 49 incident and 4 recurrent episodes of tuberculosis were diagnosed during the study period; there were no tuberculosis cases among HIV-negative women. The overall incidence rate of tuberculosis was 34.5/1000 person-years among HIV-positive women. 20 incident cases (41%) met the clinical case definition of primary disease. DNA fingerprint analysis of strains from 32 incident cases suggested 10 women (28%) may have had recently transmitted disease. 3 of 10 women who were initially purified protein derivative (PPD) skin test-negative became PPD-positive. Clinical presentation tuberculin skin testing and strain clustering data all independently suggested that substantial Mycobacterium tuberculosis transmission was occurring in HIV-infected prostitutes during the study period. As many as 26 (53%) of the 49 patients with incident disease may have recently acquired tuberculosis and DNA fingerprint analysis identified 2 (50%) of the 4 recurrent tuberculosis episodes as reinfection. These findings challenge the assumption that tuberculosis in HIV-infected individuals represents reactivation of latent endogenous infection.