An African origin for Mycobacterium bovis

Background and objectivesMycobacterium bovis and Mycobacterium caprae are the two most important agents of tuberculosis (TB) in livestock and the most important causes of zoonotic TB in humans. However, little is known about the global population structure, phylogeography and evolutionary history of these pathogens.nnMethodologyWe compiled a global collection of 3364 whole-genome sequences from M. bovis and M. caprae originating from 35 countries and inferred their phylogenetic relationships, geographic origins and age.nnResultsOur results resolve the phylogenetic relationship among the four previously defined clonal complexes of M. bovis, and another eight newly described here. Our inferences indicate that M. bovis emerged in East Africa likely between the 4th and 10th century. While some M. bovis groups remained restricted to East- and West Africa, others have subsequently dispersed to different parts of the world.nnConclusions and implicationsOur results allow a better understanding of the global population structure of M. bovis and its evolutionary history. This knowledge can be used to define better molecular markers for epidemiological investigations in settings where whole genome sequencing cannot easily be implemented.nnLay SummaryMycobacterium bovis and M. caprae are both the most important agents of tuberculosis in livestock and zoonotic tuberculosis in humans. Using phylogenetic and molecular clock inferences based on an extensive collection of whole-genome sequences we provide new insights into the global population structure, phylogeography and evolutionary history of these pathogens.