The introductory "Beekeeping in Western Canada" recommends treating with Fumagilin in Fall.
I did my first year, but not since.
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex38
"Honey Bee Pests and Diseases" published by CAPA, recommends treatment at the Economic Threshold of a million spores per bee.
Based on how quickly stocks of Fumagilin sold out at the local bee supply store, I'm thinking a lot of beekeepers up here are, or were, using it prophylactically. I don't think Alison McAfee was out of line with her thinking on that issue, at least for this part of the world.
Brian
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