Like it or not, the ticks are advancing and Canadians will have to adapt

Climate change is driving disease-carrying tick populations into new habitats across southern Canada, with various species migrating north from the United States at a rate of 35 to 55 kilometres per year. Public health data shows an exponential rise in Lyme disease cases, climbing from 144 reported cases in 2009 to a preliminary count of 7,105 in 2025, according to the Public Health Agency of Canada.

Did You Know? Canada is home to more than 40 different species of ticks, a number that continues to grow as climate patterns allow new varieties to survive and reproduce in regions previously too cold for them to inhabit.

How climate change facilitates tick expansion

Rising temperatures and shifting weather patterns are the primary drivers behind the northward movement of ticks. According to Katie Clow, an assistant professor in the department of population medicine at the University of Guelph, historical climates in Canada were previously too cold to support tick populations, causing them to starve. Longer, warmer summers now provide the necessary conditions for these pests to feed and reproduce, even surviving winter cold snaps by sheltering under leaf layers.

The expansion is further aided by migratory birds and host animals like deer and rodents, which transport ticks into new territories. As human development pushes into wooded areas, this “forest fragmentation” creates environments where deer and rodent populations thrive, providing more hosts for the ticks. Negar Elmieh, a scientist with the National Collaborating Centre for Environmental Health at the B.C. Centre for Disease Control, notes that tick populations are expanding along riverbeds and paths where these animals travel.

Health risks and the “new norm”

The establishment of blacklegged ticks—the primary carriers of Lyme disease—across Canadian provinces has introduced significant health concerns. Beyond Lyme disease, which can cause fever, fatigue, and serious complications if left untreated, other species are emerging. The lone star tick, found in small numbers across the country, is linked to a severe red meat allergy in humans, while the Asian longhorned tick has raised concerns among agricultural producers due to its potential impact on cattle.

Expert Insight: The northward migration of ticks represents a significant shift in public health, moving from isolated incidents to a broader, year-round environmental risk. As these populations establish themselves in suburban and recreational areas, the burden of disease prevention shifts from reactive treatment to consistent, proactive personal care, such as regular tick checks and landscape management.

What to expect in the coming decade

Experts anticipate that the invasion process will continue as ticks fill available ecological niches across southern Canada. According to Clow, it is likely that areas currently without established tick populations will see them emerge over the next ten years. While extreme weather events, such as heat domes with temperatures exceeding 40 C, can kill off local populations, the long-term trend remains a consistent increase in tick prevalence.

To mitigate these risks, health officials recommend standard precautions during outdoor activities. These include wearing long sleeves and light-coloured clothing, tucking pants into socks, using DEET, and performing thorough body checks after spending time outside. Showering after outdoor exposure and running clothing through a dryer can help remove and eliminate ticks that have not yet attached to the skin.

Frequently Asked Questions

Are ticks being dropped from planes to infect the population?
No. While such claims have appeared on online conspiracy forums, researchers state that the spread of ticks is entirely predictable based on climate change patterns and the migration of host animals.

Which tick stage is considered the most dangerous?
According to Katie Clow, the nymph, or “teenage,” stage of the blacklegged tick is particularly concerning because the ticks are smaller and more difficult to detect. This stage typically peaks in June and early July.

Can cold Canadian winters kill off tick populations?
According to Clow, cold winters are not sufficient to eradicate established tick populations. Ticks can survive winter cold snaps by hiding under layers of leaves, provided they have enough warmth throughout the rest of the year to reproduce.

What steps are you taking to protect your family from tick exposure during your time outdoors?