Lyme disease continues to rise in Quebec and climate change is partially to blame

Cases of Lyme disease and other tick-borne illnesses have been on the rise in Quebec for over a decade, and experts are pointing to climate change as a contributing factor. Kirsten Crandall, a scientific adviser with the Institut national de santé publique du Québec (INSPQ), explains that rising temperatures are creating ideal conditions for ticks to thrive, especially in southern Quebec. As host animals like birds and deer move north, ticks are expanding their range, particularly black-legged ticks, which are known to transmit Lyme disease.

Lyme disease, caused by a bacterium transmitted through black-legged tick bites, can have serious consequences if left untreated. Dr. Donald Vinh, an infectious disease specialist at McGill University Health Centre (MUHC), warns that advanced stages of Lyme disease can lead to heart and neurological symptoms, requiring intravenous antibiotics for treatment. Prevention is key in avoiding the potentially severe outcomes of Lyme disease.

The number of reported Lyme disease cases in Quebec has been steadily increasing, with 653 cases in 2023 compared to 127 in 2014. The majority of cases are now being acquired within the province, indicating that Quebec has become an endemic region for Lyme disease. With the black-legged tick population expanding, communities and governments are urged to plan for future outbreaks.

Mapping projections by the INSPQ show ticks spreading into new regions in Quebec, including Saguenay, the Lower St. Lawrence, and the Gaspé. As temperatures continue to rise, tick populations are expected to thrive in cooler areas previously unaffected. Most Lyme infections occur in the spring and early summer when young ticks are in the nymph stage, making them harder to detect.

While Lyme disease is becoming more prevalent in Quebec, Crandall emphasizes that it is not a cause for alarm but rather a call for increased vigilance and prevention. The INSPQ and Health Ministry are working to educate the public about tick bite prevention, with resources available on the Health Ministry’s website. Additionally, tools like eTick.ca allow individuals to report and identify ticks, as well as receive guidance on bite prevention.

Despite a slower start to tick reports in 2025 due to cooler weather, experts anticipate a continued expansion of black-legged ticks into new areas. It is essential for Quebecers to stay informed and take necessary precautions when venturing into tick-prone areas. By raising awareness and implementing preventive measures, the spread of Lyme disease and other tick-borne illnesses can be mitigated in the future.