There were 959 probable and confirmed cases of Lyme disease reported in Ontario in 2017. This was three times higher than the 5-year (2012–2016) average of 313, according to surveillance published in the Canadian Communicable Diseases Report (CCDR).


Data for confirmed and probable Lyme disease cases with episode dates from January 1, 2012, through December 31, 2017, were extracted from the integrated Public Health Information System (iPHIS). In 2012, there were only 173 confirmed and probable cases in Ontario; by 2017, that number was 959.

The majority of cases in 2017 were reported by Leeds-Grenville and Lanark District (LGL), Kingston‑Frontenac, Lennox and Addington (KFL) and Ottawa.

Ontario Lyme disease incidence in 2017 was at its highest recorded level since it became a reportable disease in 1988 acknowledging the true incidence of an infection such as Lyme disease is subject to varying degrees of underreporting due to a variety of factors.

Researchers conclude this trend is likely to continue as climate change progresses and enables blacklegged ticks to survive and propagate in new areas.

Another CCDR study showed 30 percent of Ixodes scapularis ticks sampled near Ottawa, Ontario, carried the bacterium,  Borrelia burgdorferi that causes Lyme disease.