Mining a Major Contributor to Sub-Saharan Africa's Tuberculosis Epidemic

As many as one-third of new tuberculosis (TB) cases in sub-Saharan African--or about 750,000 cases annually--may be attributable to mining.

Researchers at Brown University (Providence, RI, USA), Oxford University (United Kingdom), and other institutions used multivariate regression to estimate the contribution of mining activity in 44 sub-Saharan African countries to TB incidence, prevalence, and mortality, as well as the rates of TB among people living with HIV, with controls for economic, health system, and population confounders.

The results showed that mining production was associated with higher population TB incidence rates, corresponding to about 33% higher TB incidence after adjustment for economic and population controls. Similar results were observed for TB prevalence and mortality, as well as with alternative measures of mining activity. Independent of HIV, there were significant associations between mining production and TB incidence in countries with high HIV, as well as between log gold mining production and TB incidence in all of the studied countries. In some countries, the incidence of TB among miners was 10 times higher than that of the general population.

The researchers attribute the high incidence of TB among miners to multiple factors, including silica dust in mines, crowded working and living conditions, and the rampant spread of HIV, which weakens the body's immune system. Additionally, many mineworkers are migrants and are exposed to multiple TB risk factors, including health-care disruption and low socioeconomic status. The children, wives, and friends of these workers are also at higher risk, given the migratory pattern that has most miners traveling back and forth from their home countries several times a year. The study was published in the June 2010 issue of the American Journal of Public Health.

"We have long known that the conditions on the mines - both above and below ground - are conducive to the spread of TB and HIV. But this is the first time we have used statistical techniques to accurately quantify the contribution of mining to TB,” said lead author Mark Lurie, Ph.D., M.P.H., an assistant professor of medical science at Brown University. "It is a sad irony that precious minerals and metals coveted around the world cause such great harm in their production. Our research points to the urgent need to improve the living and working conditions on African mines as an effective public health intervention.”

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