In this study, a team of scientists led by Dr. Igor Mokrousov from St. Petersburg's Pasteur Institute demonstrated that the evolutionary history of the causative agent of tuberculosis (TB) has been shaped by human migration patterns.
The researchers examined the genetic signatures of over 300 strains of Mycobacterium tuberculosis, rod-shaped bacteria that, when airborne, infect the pulmonary systems of vulnerable individuals and give rise to clinical TB. The World Health Organization (WHO) estimates that TB kills 5,000 people worldwide every day, or approximately 2 million people each year. The pathogen is rapidly spreading and evolving multi-drug resistant strains in susceptible regions such as Africa. Interestingly, a strong gender bias in TB infection is reported globally each year; a 70% excess of male TB cases is typical.
"M. tuberculosis also has a remarkable ability to persist in the human host as a latent, asymptomatic form," explains Mokrousov. "This is probably what permitted M. tuberculosis to co-exist with humans during pre-industrialized times, when the primary mode of transmission was within families or households where there was significant physical contact." Today, approximately one-third of the world's population are carriers of latent TB.
Mokrousov's team hypothesized that, given the strong gender bias of TB infectivity and the likely family-based mode of TB transmission during pre-industrialized times, M. tuberculosis dissemination h
Contact: Maria A. Smit
Cold Spring Harbor Laboratory