I've never seen it in BC or Ontario, either and hunted bunnies all my childhood in Southern Ontario. The cottontails there ran the 7 year cycle, but never saw sick ones, only 'fast' ones.

Here, in BC, we head shoot snowshoe hares with our flintlock and caplock rifles, but in Ontario, I'd never shot one with a rifle - always running too fast - we only used shotguns.