When raccoon rabies re-emerged in Ontario last fall, one of the big questions was “where did it come from?” It had been eradicated from the province and control measures were in place at the borders to reduce the risk of re-introduction. It was assumed that a rabid raccoon hitched a ride across the border from northwestern New York state and made it into the Hamilton region (outside the border area where rabies prevention measures were greatest).
Further genetic analysis of the raccoon-variant rabies virus that was found in Hamilton has essentially confirmed that it did indeed come from New York state, but it doesn’t seem to be from the closest border area as expected. As reported by the Canadian Press, Susan Nadin-Davis, a researcher with the Canadian Food Inspection Agency, compared the genetic sequence of the Hamilton virus with strains from different parts of the northeastern US. Surprisingly, “the virus is closely related to a strain from southeastern New York state, and quite distinct from the strains found closer to the border.”
Rather than a (still impressive) hitch-hike of 100 km or so from northwestern New York, past the rabies control zone in the Niagara Region and into Hamilton (where it infected other raccoons and and then spread into the skunk population as well), the index animal’s road trip was likely more like 500 km.
That road trip has caused a big problem in Ontario, with ongoing transmission in the raccoon and skunk populations (128 cases detected at last report) and a widening control zone (that now includes where I live).