Mining industry in Africa is making TB epidemic worse

The presence of a large mining sector in African countries is a strong influence on the severity of a country’s TB epidemic, especially in countries with a high HIV prevalence, and more needs to be done in the mining industry to control TB, a new Oxford University-led study has found.

The mining industry may be creating the conditions for around 750,000 TB infections every year in Africa, the researchers estimate, and is probably the second biggest driver of expanding TB epidemics after HIV infection across the continent. Overall, around 2.3 million new TB cases occurred in sub-Saharan Africa in 2005.

Researchers at Oxford and Brown universities, the University of California, San Francisco and the London School of Hygiene and Tropical Medicine conducted a multivariate analysis of factors associated with national TB incidence in 44 countries in sub-Saharan Africa, controlling for social, economic and population factors, using data from 2008-9 for health and 2001-2005 for the mining industry.

In particular they looked at the size of the mining sector, and tried to analyse whether the mining sector itself was influencing the spread of TB, or whether high HIV prevalence among miners explained any apparent association between the mining sector and TB.

They found that both the number of mines in a country and the presence of a mining sector that was larger than the African average strongly influenced the number of incident TB cases. Mining for gold was strongly associated with a higher TB burden, regardless of a country’s HIV prevalence, probably due to much higher silica exposure in gold mines.

In countries with high HIV prevalence, mining was more likely to be associated with HIV/TB coinfection.

There are numerous explanations for the association, say the researchers. Poorly ventilated conditions in the mines and hostels increase the risk of transmission. Silica dust increases the risk of developing TB. Migration back and forth between home and mine reduces the likelihood of diagnosis and increases the chance of treatment interruption and failure. Health care for mine workers is often poor and TB screening by employers is inconsistent and unverified.

“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.

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 by improving cramped hostel living quarters and reducing exposure to silica dust.

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 – further increasing the risk of TB because immune systems are weakened.”

“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.

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.

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 prisons 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.’

The AIDS Rights Alliance for Southern Africa issued a series of recommendations in 2008 designed to improve cross-border control of TB in mineworkers:

**The establishment of systems for better prevention, diagnosis and treatment of TB and HIV for miners, ex-miners and their families in Lesotho and South Africa;

**The strengthening of linkages between TB and HIV programmes in Lesotho and South Africa, and between the public and private sectors – including the establishment of bi-national information and administrative systems to support continuity in TB prevention, diagnosis, treatment and care for miners, ex-miners and their families;

**Ensuring the rights of miners, ex-miners and their families are protected and fulfilled, which include access to health care and compensation guaranteed under South African law and the Constitution of the country.