Climate change is causing ticks to move into new regions in southern Canada, with experts predicting their continuous spread. Previously uncommon in Canada, disease-carrying ticks are migrating north from the United States at a pace of 35 to 55 kilometers per year. According to Katie Clow, an assistant professor at the University of Guelph, areas in southern Canada currently without ticks are expected to see their emergence within the next decade.
The introduction of Lyme disease in southern Ontario in 1989 by blacklegged ticks, also known as deer ticks, marked the beginning of their spread across the country. These ticks, responsible for transmitting Lyme disease and in rare cases the Powassan virus, have since been detected in various provinces including Alberta and Saskatchewan. Health Canada reports that Canada now hosts over 40 tick species, some posing serious health risks.
Clow emphasizes that it is a matter of time before these tick species establish themselves in Canada, citing the surprising emergence of ticks in previously unaffected regions. The rise in tick populations has been particularly notable in Saskatchewan and Montreal, where record numbers of Lyme disease cases have been reported. Surveillance by the Public Health Agency of Canada reveals a substantial increase in Lyme disease cases from 2009 to 2025.
The proliferation of ticks has been linked to climate change, which has created more favorable conditions for their survival and reproduction. Ticks arriving with migratory birds and host animals find the necessary warmth to thrive, even surviving cold winters under leaf layers. As a result, some tick species have become a year-round concern, especially in suburban areas where forest fragmentation supports their populations.
Negar Elmieh from the B.C. Centre for Disease Control notes that climate change has facilitated the northward expansion of ticks, following the migration patterns of host animals. Elmieh describes the increasing tick populations as the new normal for Canadians, urging people to take precautions when engaging in outdoor activities. Recommendations include wearing protective clothing, using insect repellent, regularly checking for ticks, and implementing tick management strategies in outdoor spaces.
The ongoing spread of ticks underscores the importance of awareness and preventive measures to mitigate the risks associated with tick-borne diseases in Canada.
