Warmer winters are contributing to a rise in tick-borne illnesses across Canada, prompting warnings from health experts. The Public Health Agency of Canada (PHAC) reports a sharp increase in Lyme disease cases, climbing from 917 in 2015 to over 5,200 preliminary cases in 2024. However, the true number is likely much higher due to undiagnosed or unreported infections.
Dr. Isaac Bogoch, an infectious diseases specialist at Toronto General Hospital, notes that milder winters enable ticks to survive and thrive in more northern latitudes. This has led to a rise in not only Lyme disease, but also other tick-borne infections previously unseen in Canada, such as anaplasmosis and babesiosis, both now reportable diseases in Ontario. Last summer, Ontario recorded two cases of Rocky Mountain spotted fever believed to have been acquired in Long Point, a region where it was not previously observed.
The trend extends beyond Ontario. Montreal public health officials recently reported 161 cases of Lyme disease in 2025, the highest number since 2003. The Quebec government attributes this increase to climate change, which allows ticks to survive more easily. Since 2024, the entire Island of Montreal has been considered at risk for tick exposure.
Canadians are advised to take preventative measures when in areas known to have ticks. These include wearing protective clothing, using insect repellent, and checking for ticks after spending time outdoors. Early detection and treatment are crucial in managing tick-borne illnesses.
