This is a little more deeply engrained than from an outbreak of a single disease. The thing that is bizarre is that Ontarians respond to disease similar to how the Japanese cultural response has been to radiation.
The only thing is Japan had two nuclear bombs dropped on it. Ontario has at most one outbreak of an infectious disease, which didn't really do a god damn thing; 44 Torontonians died from SARS... but by the average incidence of accidents over 5100 Torontonians literally died because 'shit happens'.
It's so completely bizarre to an outsider. I mean if this is a corollary to all North Americans, if I go to New York I expect everyone to duck and cower on the ground whenever they hear the sound of a plane. But they don't.