Ticks are expanding their range across Canada at an alarming rate, bringing with them a growing threat of Lyme disease and other illnesses. Reported Lyme disease cases have skyrocketed from 522 in 2014 to 5,239 in 2024, according to the Public Health Agency of Canada. To understand this surge, the National Post consulted three experts: Manisha Kulkarni, a professor at the University of Ottawa's School of Epidemiology and Public Health; Virginie Millien, a biologist at McGill University; and Luis Anholeto, lab manager at the Canadian Tick Research and Innovation Centre at Acadia University. Their insights reveal a rapidly changing landscape of tick populations and associated health risks.
How Big Is Canada's Tick Problem Now Compared to a Decade Ago?
Kulkarni notes a dramatic increase in tick populations over the last decade, particularly blacklegged ticks (deer ticks) that carry Lyme disease. A decade ago, established populations were confined to pockets of southern Manitoba, southern and eastern Ontario, southern Quebec, New Brunswick, and Nova Scotia. Now, these ticks have expanded northward in all provinces, including around major urban centers like Toronto, Ottawa, and Montreal.
Which Parts of the Country Have Been Hit Hardest?
Millien identifies Ontario as a hotspot, leading in tick abundance and Lyme disease cases, with Quebec close behind. Anholeto adds that Nova Scotia has consistently had the highest incidence rates nationwide. The map of tick distribution continues to shift, with new areas becoming colonized each year.
What's Driving the Spread, Especially Climate Change?
Kulkarni emphasizes that climate change and warming temperatures are major drivers. Warmer conditions allow ticks to survive farther north and extend their active season. Land-use changes, such as urban expansion into woodlands and forest fragmentation, create ideal habitats for white-tailed deer and white-footed mice—key hosts for ticks. Millien points out that historically, ticks could not survive Canadian winters, but now they do, leading to local reproduction and pathogen circulation.
Which Tick-Borne Illnesses Should People Worry About?
Kulkarni states that Lyme disease is the most common and can be serious if untreated. Other rising threats include anaplasmosis, babesiosis, and Powassan virus. Anholeto notes that anaplasmosis is increasing, while Powassan virus, though rare, can cause encephalitis. Rocky Mountain spotted fever, a rare but deadly infection, is also spreading northward due to climate change.
Experts advise using insect repellent, wearing long sleeves and pants in wooded areas, and performing thorough tick checks after outdoor activities. Prompt removal of attached ticks reduces the risk of disease transmission.
