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AIDS. 2000 Dec 1;14(17):2759-68.

HIV infection and silicosis: the impact of two potent risk factors on the incidence of mycobacterial disease in South African miners.

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Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, UK.



To investigate the combined effects of HIV infection and silicosis on mycobacterial disease.


A retrospective cohort of 1374 HIV-positive and 2648 HIV-negative miners who attended a South African gold mining hospital and primary health clinics.


Miners who had been tested for HIV, with consent, at primary health clinics during 1991-1996, predominantly because of a symptomatic sexually transmitted disease.


Tuberculosis (TB) incidence was 4.9 and 1.1 per 100 person-years in HIV-positive and HIV-negative miners respectively. The incidence of Mycobacterium kansasii disease was also high (0.32 and 0.10 per 100 person-years, respectively). Silicosis was highly prevalent, implying inadequate dust control, and was a significant TB risk factor among both HIV-positive and HIV-negative men (adjusted incidence rate ratios 1.4-2.5 according to radiological severity). The data were consistent with the risks of silicosis and HIV combining multiplicatively, but did not fit an additive model. The incidence of HIV-associated TB increased significantly during the study, with no corresponding change in HIV-negative rates, to reach 16.1 per 100 person-years among HIV-positive silicotics.


The risks of silicosis and HIV infection combine multiplicatively, so that TB remains as much a silica-related occupational disease in HIV-positive as in HIV-negative miners, and HIV-positive silicotics have considerably higher TB incidence rates than those reported from other HIV-positive Africans. The increasing impact of HIV over time may indicate epidemic TB transmission with rapid disease development in HIV-infected miners. Similar but currently unrecognized interactions may be contributing to TB control problems in other industrializing countries affected by the HIV epidemic.

[Indexed for MEDLINE]

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