What researchers described as a "radical" bid to cut down on tuberculosis (TB) infections among South African gold miners has failed to prevent infections or deaths, said a study released on Wednesday.
A high proportion – as much as 3% – of miners begin treatment for the contagious lung disease each year.
Tuberculosis spreads easily among miners due to the close quarters in which they work, and the epidemic has worsened along with the rise in HIV infections, according to the article in the New England Journal of Medicine.
The clinical trial led by scientists at the London School of Hygiene and Tropical Medicine offered thousands of South African miners a preventive drug therapy called isoniazid over the course of nine months. Previous research showed the drug was effective at preventing latent tuberculosis infection from progressing to full-blown disease. But this trial showed that while the therapy did appear to prevent TB while the participants were taking it, the effects quickly wore off once they stopped.
One year after the end of the intervention, researchers did not find any difference in the number of TB cases among workers in the mines where TB preventive therapy was offered, compared to mines that continued their standard practices. The trial therefore did not reduce the number of cases or deaths from the disease.
"HIV, exposure to silica dust in the mines and close working and living conditions predispose South African gold miners to TB," said lead investigator Alison Grant, a professor of international health. "As conventional control methods were not working, we investigated a radical approach to TB control. Our study shows that isoniazid preventive therapy works while people take it, but, in this setting, the effect was not enough to improve overall TB control."
The findings suggest that a better approach might include a combination of factors, from better TB testing to prompter treatment for TB as well as HIV, along with preventive therapy regimens.
According to the World Health Organisation, TB is closely behind Aids as the top infectious killer worldwide. More than eight-million people were sickened by TB in 2012 and 1.3-million died from it. – Sapa-AFP