Dispersal of M. tuberculosis via the Canadian Fur Trade

Very little is known about the migration dynamics of Mycobacterium tuberculosis, the causative agent of tuberculosis. In order to better understand dispersal patterns of this important human pathogen, we studied European lineages of M. tuberculosis currently circulating in indigenous North American communities. Our analyses of genetic and other data suggest that the Canadian fur trade (1710-1870) was an important conduit of M. tuberculosis from European immigrants to Aboriginal peoples. M. tuberculosis populations appear to have persisted in indigenous communities at very low densities (bacteria Ne~2) for about a century before abruptly expanding, following environmental changes that favored the pathogen. These unusual migration dynamics may help explain the low DNA sequence diversity observed among isolates of M. tuberculosis and likely contribute to difficulties in the global elimination of tuberculosis.

Speaker: Dr. Pepperell is interested in evolutionary relationships among pathogens and human hosts. Some of her current projects focus on how cultural, economic and historical influences shape patterns of disease transmission and, in turn, evolution of M. tuberculosis. Genetic & epigenetic mechanisms underlying this organism's ability to adapt to its natural environment are subjects of other investigations. She also studies Aboriginal North Americans in order to better understand health disparities affecting these populations. Dr. Pepperell earned her MD at Queen's University in Ontario and her professional certifications from the University of Toronto and Stanford University. She is presently an Instructor of Medicine and Infectious Diseases at Stanford Medical School.