New Genetic Insights Show How Tuberculosis May Be Evolving to Become More Dangerous (preview)

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Tuberculosis seems to be evolving in unexpected ways that outsmart humans

By Sally Lehrman

Image: Daniel Chang

In Brief

• More than one million men, women and children around the globe die of tuberculosis every year, and about a third of the world's population harbors a latent infection.
• A growing number of studies suggest that TB may be evolving into a new bug that is far more deadly, spreads more quickly and is more likely to become resistant to treatment with antibiotics.
• Designers of new treatments should take these latest findings into account if they do not want to make matters worse. Changing the host environment with improved housing, for example, may also prove key.

Today most people in the richer parts of the world think of tuberculosis, if they think of it at all, as a ghost of history. Throughout ancient times the tenacious bacterial infection consumed the bodies of untold millions, rich and poor, filling their lungs with bloody sputum. As TB spread in the centuries that followed, it continued to attack across economic and class lines, affecting both the famous and the obscure. Among its better-known victims: poet Manuel Bandeira, writers Emily and Anne Bront?, and sculptor Fr?d?ric-Auguste Bartholdi, who designed the Statue of Liberty. By the early 20th century humanity had begun fighting back with public health campaigns, improved living standards, and eventually antibiotics and a modestly effective vaccine. Although in 2011 TB sickened nearly nine million people, killing 1.4 million of them, mostly in the poorer regions of the globe, the mortality rate has nonetheless fallen by more than a third since 1990. Things are looking up?or so it may seem.

New genetic research, however, suggests that the bacterium responsible for TB could be poised to emerge stronger and more deadly than ever before?and not just because some strains have become resistant to treatment with the standard set of antibiotics. A small but increasingly influential group of investigators believes that the microbe, Mycobacterium tuberculosis, may have evolved along an unexpected and particularly dangerous path. The scientists have discovered that TB can be divided into seven families of genetically related strains, at least one of which is surprisingly virulent, prone to drug resistance and especially well suited to spreading disease in our increasingly interconnected, densely populated world.

This article was originally published with the title The Diabolical Genius of an Ancient Scourge.

Source: http://rss.sciam.com/~r/sciam/basic-science/~3/NWdAXdPsys4/article.cfm

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