There seems to be a renewed concern about Lyme Disease this year with some good information floating around but also a lot more worry than I think is justified. Lyme Disease is a serious concern but in Ontario it is limited to a few very small areas.
Here are a couple of useful links if you are wondering where you would be at risk of being exposed to Lyme Disease bearing ticks:
1) The first is a map of Lyme Disease Risk Areas from Public Health Ontario. A risk area is defined as a 20km radius from where a
deer tick has been found. The deer tick(s) found did not have to be infected with Lyme Disease, so while it is a good medical & biological definition of a risk area, the resulting areas shown are much larger than any know instance of Lyme Disease infected ticks in Ontario:http://www.publichealthontario.ca/en/eRepository/Lyme_Disease_Risk_Areas_Map_2015.pdf
2) The second is a map of known locations where Lyme Disease has actually been found. This is from a Canada Communicable Disease Report and gives you a much better idea of where Lyme Disease is actually found.http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/14vol40/dr-rm40-05/dr-rm40-05-1-eng.php
From what I see in the CCDR report, the known areas where Lyme Disease exists in Ontario do not appear to have changed significantly since the early 1990's when I was working on a Lyme Disease research project at the University of Guelph.