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

AIDS. 2000 Dec 1;14(17):2759-68. doi: 10.1097/00002030-200012010-00016.


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

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

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

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS-Related Opportunistic Infections / complications
  • AIDS-Related Opportunistic Infections / epidemiology
  • Adolescent
  • Adult
  • Cohort Studies
  • Gold
  • HIV Infections / complications*
  • HIV Seropositivity / complications
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Mining*
  • Mycobacterium Infections / complications*
  • Mycobacterium Infections / epidemiology*
  • Mycobacterium Infections, Nontuberculous / complications
  • Mycobacterium Infections, Nontuberculous / epidemiology
  • Prevalence
  • Retrospective Studies
  • Risk Factors
  • Silicosis / complications*
  • Silicosis / epidemiology
  • South Africa / epidemiology
  • Time Factors
  • Tuberculosis / complications
  • Tuberculosis / epidemiology


  • Gold