Hoary TB
The tuberculosis (TB) germ is far older than believed, predating diseases such as the plague. TB was thought to be a few tens of thousands years old. But a molecular analysis by scientists at the Paris-based Institut Pasteur shows Mycobacterium tuberculosis is about 3 million years old.
M tuberculosis and its close variations cause most modern cases of TB. However, some patients from East Africa the scientists were studying, were infected with unusual strains that form colonies physically different from the predominant strains. Using this genetic data, the scientists discovered that modern strains evolved from these now-rare strains. "Tuberculosis could thus be much older than the plague, typhoid fever, or malaria, and might have affected early hominids,' said Veronique Vincent, senior author of the study appearing in the inaugural issue of PLoS Pathogens. The researchers postulate that TB's expansion throughout the world may have coincided with human migration out of Africa.
TB is re-emerging across parts of Europe, Asia and Africa, killing three million people each year. Understanding the origins of the bacterium could help develop new drugs to combat TB.