Complex Population Structure of /Borrelia burgdorferi/ in
Southeastern and South Central Canada
as Revealed by Phylogeographic Analysis. */
/Mechai, S., Margos, G., Feil, E. J., Lindsay, L. R., &
Ogden, N. H. (2015)./
Applied and Environmental Microbiology/, /81/(4), 1309-1318.
doi.org/10.1128/AEM.03730-14Abstract
Lyme disease, caused by the bacterium Borrelia burgdorferi
sensu stricto, is an emerging zoonotic disease in Canada and
is vectored by the blacklegged tick, Ixodes scapularis. Here
we used Bayesian analyses of sequence types (STs),
determined by multilocus sequence typing (MLST), to
investigate the phylogeography*(see below) of B. burgdorferi populations in southern Canada and the United States by analyzing MLST data from 564 B. burgdorferi-positive samples collected
during surveillance.
A total of 107 Canadian samples from field sites were
characterized as part of this study, and these data were
combined with existing MLST data for samples from the United
States and Canada. Only 17% of STs were common between both
countries, while 49% occurred only in the United States, and
34% occurred only in Canada.
However, STs in southeastern
Ontario and southwestern Quebec were typically identical to
those in the northeastern United States, suggesting a recent
introduction into this region from the United States.In contrast, STs in other
locations in Canada (the
Maritimes; Long Point, Ontario; and southeastern Manitoba)
were frequently unique to those
locations but were putative
descendants of STs previously found in the United States.
The picture in Canada is consistent with relatively recent
introductions from multiple refugial populations in the
United States.
These data thus point to a geographic pattern of populations
of B. burgdorferi in North America that may be more complex
than simply comprising northeastern, midwestern, and
Californian groups. We speculate that this reflects the
complex ecology and spatial distribution of key reservoir
hosts.
(Trav added the asteric above and below and the definition below)
* phylogeography = is the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals. This is accomplished by considering the geographic distribution of individuals in light of the patterns associated with a gene genealogy.