US soldiers in high-tuberculosis areas face new epidemic: false...( U.S. Army service members are increa...),Health

U.S. Army service members are increasingly deployed in regions of the world where tuberculosis (TB) is rampant, such as Iraq and Afghanistan, and the military now faces a growing medical problem. But it is not TB itself that is on the riseinstead, the problem lies with the growing number of pseudoepidemics, or clusters of false-positives for TB that are the result of universal testing with a notoriously inaccurate tuberculin skin test (TST) and inconsistent procedures for interpreting those tests in low-risk populations.

These false positives tests have become more than a mere institutional inconvenience or a momentary medical scare for Soldiers being tested. They are a real financial and medical burden because they inappropriately diverting limited funds and resources.

A recent study, published in American Thoracic Societys first issue for June of the American Journal of Respiratory and Critical Care Medicine, describes eight outbreaks of false-positive TB tests between 1983 and 2005. The study was led by U.S. Army Major James Mancuso, M.D., of the Uniformed Services University of the Health Sciences.

Recent deployments to Iraq and Afghanistan, which are reported to have among the highest rates of active TB in the world, have raised concerns about TB exposure. However, many service members do not have sufficient contact with locals to raise their risk of contracting TB. As a consequence, testing after recent deployments to the endemic and hyperendemic areas has occasionally resulted in large numbers of U.S. Army service members with [positive tests] and massive efforts aimed at preventing active TB, wrote Dr. Mancuso.

Because the positive-predictive value of a testthat is, the likelihood of a positive result indicating an actual caseis dependent on the prevalence of disease in a population. The lower the prevalence of a disease, and the higher the variability in the test and testing procedures, the less the positive-predict
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