Invasion of the ticks: Watch their remarkably fast spread across Canada

This graph shows the rise of ticks in Canada, and the rate of their population spreading across the provinces from 1977 to 2024.

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Ticks are pushing farther across Canada every year, and the diseases they carry are coming with them. Reported Lyme disease cases climbed from 522 in 2014 to 5,239 in 2024, according to the Public Health Agency of Canada.

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National Post reached out to three experts for more information on where ticks are spreading, why and how to stay safe. Manisha Kulkarni is a professor at the University of Ottawa’s School of Epidemiology and Public Health. Virginie Millien is a biologist at McGill University. Luis Anholeto is a lab manager at the Canadian Tick Research and Innovation Centre at Acadia University.

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Millien spoke by phone. Kulkarni and Anholeto responded by email. Their answers have been edited and condensed for clarity and length.

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How big is Canada’s tick problem now compared to a decade ago?

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Kulkarni: We’ve seen a dramatic increase in tick populations across Canada in the last decade, especially the blacklegged ticks (deer ticks) that can carry Lyme disease. Ten years ago, there were established tick populations in defined pockets of southern Manitoba, southern and eastern Ontario, southern Quebec, New Brunswick and Nova Scotia, but since then we’ve seen an expansion of these populations further north in all provinces, including around major population centres like Toronto, Ottawa and Montreal.

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Which parts of the country have been hit hardest, and is that map still changing?

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Millien: Ontario is actually a hotspot. It’s number one in terms of abundance of ticks and number of Lyme disease cases. Quebec is not far behind, but Ontario, this is where it started, Long Point.

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Anholeto: Nova Scotia has consistently had the highest incidence rates in the country.

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Blacklegged ticks are often found in wooded and forested areas, especially areas with thick underbrush. Photo by Getty Images

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What’s driving the spread, and how much of it comes down to climate?

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Kulkarni: Climate change and the associated warming temperatures are a major force behind the spread of blacklegged ticks in Canada. They can survive further north, where it was once too cold, and there’s a longer warm season for them to complete their life cycle. But other factors, like land-use changes, are also at play. Urban expansion into woodlands and resulting forest fragmentation creates an ideal habitat for white-tailed deer and white-footed mice, and in turn, ticks.

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Millien: Up until recently, none of them would survive the winter. But now that we have ticks that survive, they reproduce locally, so the pathogen is circulating and it’s established.

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Which tick-borne illnesses should people actually worry about, and how serious are they?

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Kulkarni: The most common tick-borne illness in Canada is Lyme disease, which can be very serious if it’s not treated promptly. Other serious tick-borne illnesses are also on the rise, such as Anaplasmosis, Babesiosis and Powassan virus.

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Anholeto: Beyond Lyme, anaplasmosis is increasing in Canada. Powassan virus is rare but can cause encephalitis. We also have Rocky Mountain spotted fever, a rare but potentially deadly infection that is spreading northward in Canada due to climate change.