Ancient Pathogens

Science has an interesting article about a paper from PLoS Pathogens that has reanalysed the tuberculosis complex.

Tuberculosis (TB), an infectious disease that damages the lungs and kills approximately 2 million people each year, is caused by thousands of extremely closely related strains of bacteria collectively known as the Mycobacterium tuberculosis complex (MTBC). Their remarkable lack of genetic variation led researchers to propose that MTBC members are all the progeny of a single bug that flourished worldwide between 20,000 and 35,000 years ago. But a unique TB strain found in Africa in 1997 made some researchers wonder whether the bugs were really as homogenous, and thus as young, as scientists had believed.

Interestingly, they found that the organisms that cause tuberculosis might be even older than 35,000 years, possibly having spread to humans as early as three million years ago. That's been a long time to have gotton aquainted with us. It's interesting to note that Mycobacterium bovis, which infects farmed animals dates back roughly to the time we domesticated animals proving that for a change, we gave one of our pathogens to an animal and not the other way around.