RECENT TRANSMISSION OF TUBERCULOSIS IN A COHORT OF HIV-1-INFECTED FEMALE SEX WORKERS IN NAIROBI, KENYA

Objectives: To describe the epidemiological and clinical characteristi cs of HIV-related tuberculosis in a female cohort, and to investigate the relative importance of recently transmitted infection and reactiva tion in the pathogenesis of adult HIV-related tuberculosis. Design: Me mbers of an established cohort of female sex workers in Nairobi were e nrolled in a prospective study. Women were followed up regularly and s een on demand when sick. Methods: Between October 1989 and September 1 992 we followed 587 HIV-infected and 132 HIV-seronegative women. Stand ard protocols were used to investigate common presentations. Cases of tuberculosis were identified clinically or by culture. All available M ycobacterium tuberculosis strains underwent DNA fingerprint analysis. Results: Forty-nine incident and four recurrent episodes of tuberculos is were seen in HIV-infected women; no disease was seen in seronegativ e sex workers (P = 0.0003). The overall incidence rate of tuberculosis was 34.5 per 1000 person-years amongst HIV-infected participants. In purified protein derivative (PPD) skin test-positive women the rate wa s 66.7 per 1000 person-years versus 18.1 per 1000 person-years in PPD- negative women. Twenty incident cases (41%) were clinically compatible with primary disease. DNA fingerprint analysis of strains from 32 inc ident cases identified two clusters comprising two and nine patients; allowing for index cases, 10 patients (28%) may have had recently tran smitted disease. Three out of 10 (30%) patients who were initially PPD skin test-negative became PPD-positive. Taken together, 26 incident c ases (53%) may have been recently infected. DNA fingerprint analysis a lso identified two (50%) of the four recurrent tuberculosis episodes a s reinfection. Conclusions: Substantial recent transmission of tubercu losis appears to be occurring in Nairobi amongst HIV-infected sex work ers. It may be incorrect to assume in other regions of high tuberculos is transmission that active HIV-related tuberculosis usually represent s reactivation of latent infection.