The risks rats pose are hugely overstated, including in this very thread. Most of the world has rats -- often enormous numbers -- but we have functioning agriculture, aren't dying of weird rat diseases, etc. Notably Alberta has the same mice problem as everywhere else, and mice are a much greater threat[1]. I live in Ontario -- a warmer, much hospitable, more populous place than Alberta -- and rats somehow present zero concern in my life, despite the absence of any real control initiatives.
This is all mostly just geographical and time happenstance that baked in a situation and norm. Rats actually aren't native to North America but were introduced with Europeans. They then slowly spread, and Alberta made the choice to stop rats before they took hold in the province. So they started at zero and that made efforts to stop them from taking hold easy if sustained, especially given the brutal winters and inhospitable geography for rats.
[1] - Elsewhere someone referenced hantavirus, yet the overwhelming percentage (basically 100%) of cases of that are from mice in living spaces. Mice like the deer mice that are found throughout Alberta.
This is all mostly just geographical and time happenstance that baked in a situation and norm. Rats actually aren't native to North America but were introduced with Europeans. They then slowly spread, and Alberta made the choice to stop rats before they took hold in the province. So they started at zero and that made efforts to stop them from taking hold easy if sustained, especially given the brutal winters and inhospitable geography for rats.
[1] - Elsewhere someone referenced hantavirus, yet the overwhelming percentage (basically 100%) of cases of that are from mice in living spaces. Mice like the deer mice that are found throughout Alberta.