Mycobacterial disease in South African gold miners in the era of HIV infection

Abstract

Setting: Mining company tuberculosis (TB) clinic, Freestate Province, South Africa.

Objectives: To investigate the impact of the human immunodeficiency virus (HIV) on tuberculosis case rates and case detection methods in miners.

Design: Demographic and clinical data were extracted from the central computerised TB database for the period 1990-1996.

Results: A total of 7450 miners had TB, which was smear- or culture-positive in 81% of pulmonary cases. Incidence rates more than doubled between 1990 and 1996, from 1174 to 2476 per 100000 per year. Non-tuberculous mycobacteria, predominantly Mycobacterium kansasii, were isolated more commonly from retreatment than from new cases (19.5% and 11.5% respectively, P < 0.001). HIV prevalence in TB patients increased from 15% in 1993 to 45% in 1996 (P < 0.001). There was no significant association between HIV and smear status, but HIV-positive patients were more likely than HIV-negative patients to present passively with symptoms rather than through the active radiological screening programme (OR 1.9, P < 0.0001). The overall proportion of patients presenting passively increased from 23% in 1990 to 51% in 1996 (P < 0.001).

Conclusion: The HIV epidemic has lead to increased TB incidence in South African miners to very high rates, and appears to be impacting on the efficacy of the active radiological screening programme.