The dark side of mining for gold: research suggests mining in Africa is spreading TB

1 June 2010

Mining for gold, diamonds, and precious minerals is dangerous work, but in sub-Saharan Africa the activity could be driving an entire continent’s tuberculosis epidemic, a new Oxford-led study has found.

Researchers at Oxford and Brown universities, the University of California, San Francisco and the London School of Hygiene and Tropical Medicine estimate that the mining industry in Africa may be implicated in as many as 760,000 new cases of tuberculosis each year, due to factors such as silica dust in mines, crowded working and living conditions, and the spread of HIV.

Men travelling from afar to work in mines, such as from Botswana to South Africa, are at the greatest risk of getting tuberculosis. But their wives, children, and friends are also at high risk when miners travel back and forth to work, often many times a year.

This means that even if mining clinics successfully diagnose tuberculosis in miners and start treatment appropriately, the message is often not relayed back to doctors who work at the miners’ hometowns. The authors suggest that this disruption of treatment poses a major threat of developing a drug-resistant form of tuberculosis.

The report, published in the American Journal of Public Health, concludes that mining companies and governments must work together to achieve ‘similar levels of risk to those observed in Western mines’, especially since mines in Africa are owned by the same companies. To do this, the researchers indicate that healthcare programmes should emphasise continuity of care as miners travel across borders and they should routinely screen miners in order to detect tuberculosis at an early stage. They also highlight the need to improve poor working conditions and reduce the miners’ exposure to silica dust.

‘Improving living and healthcare conditions for miners may be necessary not only for the miners, but for controlling tuberculosis epidemics throughout sub-Saharan Africa,’ said Dr David Stuckler, from the Department of Sociology at the University of Oxford.

Tuberculosis has been on the rise in sub-Saharan Africa over the past 20 years with a doubling of the yearly annual incidence from 173 to 351 per 100,000 population between 1990 and 2007. Largely these rises are the result of the growing HIV epidemic, but the data shows that HIV is only one of several factors involved in the spread of TB in the region.

Dr Sanjay Basu, from the University of California, noted: ‘Doctors and public health experts have long known that mineral miners in sub-Saharan Africa have the greatest risk of tuberculosis of any working group in the world. According to one industry study, within about 18 months of starting work, about one out of every three miners is estimated to become infected – with HIV in some gold mines increasing the risk of TB because immune systems are weakened.’Miners are also known to spread tuberculosis to their families and communities. Nearly half of workers in large mining countries like South Africa are foreign and routinely travel across large distances. Yet the extent to which all of these risks of tuberculosis are contributing to Africa’s overall tuberculosis epidemic has not been studied until now.

The researchers took data on mining production between 2001 and 2005 and compared them with tuberculosis incidence, prevalence, and mortality rates for 44 countries in sub-Saharan Africa. Their analysis considered and controlled for a variety of potential factors involved in tuberculosis spread. Consistently, the team found evidence that mining had a significant impact on the spread of TB. The team also found that the risk appeared to be the worst in countries with high levels of HIV, associated with the living conditions around mines, and mining for gold which is believed to expose miners to the more silica dust than any other mineral. Furthermore, the researchers were able to take advantage of natural experiments when countries decreased their mining activity to show that tuberculosis rates fell more quickly (or rose less) than in neighbouring countries where mining activity remained stable or increased.

Dr Mark Lurie of Brown University said, ‘Mining is remarkably similar to the role of prisons in spreading tuberculosis throughout the former Soviet Union. The difference is that we can learn the lessons from failing to control tuberculosis in Soviet prison to avoid a crisis on the mines in sub-Saharan Africa.’

Professor Martin McKee, from the London School of Hygiene and Tropical Medicine, said ‘This study reminds us of the importance of studying the conditions in which people live and work if we are to understand their patterns of disease.

’For more information, the full study or to arrange interviews, please contact the University of Oxford Press Office on +44 (0)1865 280534 or press.office@admin.ox.ac.uk 

Notes for Editors

  • The report ‘Mining and Risk of Tuberculosis in Sub-Saharan Africa’ by David Stuckler, Sanjay Basu, Martin McKee and Mark Lurie is published in the American Journal of Public Health on 1 June 2010.
  • The research estimated that each 10% higher mining production was linked to about 0.9% higher tuberculosis rates in the 44 countries being studied.
  • Similar to existing studies, they found each 1% higher burden of HIV was linked to about 4% to 5% higher tuberculosis incidence.
  • In countries with antenatal HIV prevalence  above 4%, the researchers found that mining doubled the risk to tuberculosis spread compared to countries with HIV rates below 4%.
  • Gold mining countries had about 50% higher rates of tuberculosis than countries that did not mine for gold, after controlling for potential factors other than mining activity.