The short answer
No. Only one species, the blacklegged tick, transmits Lyme disease in Ontario. And not even all blacklegged ticks are infected.
What the data says
Ontario has at least 13 established tick species, and 43 species have been reported in the province when you count adventive and travel-related ones. Of all of those, only the blacklegged tick (Ixodes scapularis, sometimes called the deer tick) carries Borrelia burgdorferi, the bacterium that causes Lyme disease.
And even among blacklegged ticks, infection rates vary by region:
- In Ottawa, about 30% of blacklegged ticks tested positive.
- In the Dundas area, 41% tested positive.
- In the City of Toronto, prevalence sits above 20%.
So even in higher-risk areas, the majority of blacklegged ticks are not carrying Lyme. That said, one in three is not odds most people want to bet on.
Oakville and Halton Region
The Oakville area sits right along the north shore of Lake Ontario, one of the established risk zones for blacklegged ticks identified by Public Health Ontario. Halton Region has confirmed blacklegged tick populations, and the risk area has been expanding year over year.
Lyme disease is rising across Canada. The 2024 incidence rate hit 14.1 per 100,000 people, up from 11.9 the year before. Ontario, Nova Scotia, and Quebec together account for 96% of Canadian cases. For the local picture — including why Halton’s blacklegged tick infection rate jumped from 0% in 2018 to 38% in spring 2025 — see our 2026 field guide on ticks in Halton and why are there so many ticks this year.
June is the worst month for Lyme transmission risk in Ontario because of nymph-stage ticks, which are tiny and hard to detect. Whether to add the canine Lyme vaccine on top of preventive medication is a lifestyle-based call worth discussing at a visit.
Other tick-borne diseases
Other tick species in Ontario carry different diseases. Anaplasmosis, Babesiosis, and Ehrlichiosis are all tick-transmitted, just by different species and different pathogens. So tick prevention matters regardless of whether Lyme specifically is your concern.
If you find a tick on your dog, save it — don’t flush it. Bring it in or submit it through eTick for species identification, and a lab partner can test confirmed blacklegged ticks for Lyme. That beats guessing. We cover the best way to save a tick in our post on why you shouldn’t flush ticks.
Key takeaways
- Only the blacklegged tick transmits Lyme disease in Ontario. Other tick species carry different diseases.
- Not all blacklegged ticks are infected. Rates range from about 20% to 41% depending on the area.
- Oakville and Halton Region are in an established risk zone for blacklegged ticks.
- Lyme disease rates in Canada are climbing year over year.
- Save any tick you remove and bring it to your vet for identification.
References
- Public Health Ontario. “Lyme Disease.” publichealthontario.ca
- Public Health Ontario. “The Ticks of Ontario.” publichealthontario.ca (PDF)
- ClimateData.ca. “Lyme Disease in Ontario.” climatedata.ca
- Government of Canada. “Lyme Disease Surveillance.” canada.ca
- Geneticks. “Tick Testing Maps & Statistics for Ontario.” geneticks.ca