Latent infection with tuberculosis is common and some infected people develop the active form of the disease. Health-care workers (HCWs) can become infected, develop active disease, and c an pass their infection on to patients and others. Research published in PLoS Medicine shows that HCWs in developing countries are at particularly high risk. Over half were found to have latent TB.

One third of the world's population is infected with Mycobacterium tuberculosis, the bacterium that causes TB. In most people, the bug causes no health problems and it remains latent. But about 10% of infected people develop active, potentially fatal TB disease, most commonly in their lungs. More than 90% of the world's cases of TB occur in low- and middle-income countries. The researchers Rajnish Joshi at University of California Berkeley and colleagues conducted a systematic review, which involved a comprehensive search for studies that had collected data on TB infection in health-care workers in these countries. Averaged out over the 51 studies which they found, 54% of health workers had latent TB. The TB disease rates in health-care workers were also substantially higher than those in the general population of the same countries.

In high-income countries, measures are in place to reduce the TB infection risk faced by health workers. In contrast, most of the hospitals in the studies found by the researchers reported no or minimal TB control measures. The researchers say that research is needed to establish whether the control measures that have reduced TB transmission to health workers in high-income countries will work elsewhere, and whether they will be affordable.

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Contact: Andrew Hyde
press@plos.org
44-122-346-3330
Public Library of Science
25-Dec-2006