Rates of blacklegged ticks with Lyme disease infection on the rise

Temperatures are beginning to cool in northwestern Ontario this fall, but officials say tick activity is still on the rise and people spending time outdoors need to remain vigilant.

Twenty-one blacklegged ticks were submitted to the Thunder Bay District Health Unit (TBDHU) between the end of September and the end of October. That's about the same number of ticks submitted to the public health agency at the beginning of the spring season.

"I'm pretty concerned because … people seem to think that 'oh, well, now that we've had a frost, there's going to be no problem.' And there is a problem because the backlegged ticks are officially active down to four degrees." said Ken Deacon, entomologist and TBDHU vector-borne disease program coordinator.

Deacon said it's important to take precautions to prevent tick bites, as the blacklegged tick is the primary vector of the four tick-borne diseases, including Lyme disease, Powassan virus, and Anaplasmosis, and Babesiosis.

This fall, TBDHU submitted eight ticks to the National Microbiology Laboratory for testing, and five tested positive for Lyme disease. One of the ticks also tested positive for a new species of bacteria that also causes Lyme disease.

Deacon called the results "shocking," adding the percentage of infection is higher than in the past, but still not record breaking.

Blacklegged ticks were first identified in the Thunder Bay District in 2005, and now the area is considered a risk area by Public Health Ontario, along with Kenora and Rainy River areas.

The percentage of blacklegged ticks in the Thunder Bay area infected with Lyme disease was more than 40 per cent as of 2023, but most of the ticks found in the district area are wood ticks, which do not carry Lyme disease.

Deacon said a harsh and long lasting cold snap with no snow would help to control the tick population, but those conditions are becoming less frequent as the climate continues to change.

"It means it is going to expand. They're heading north," said Deacon, talking about the impact of climate change on tick populations. "It's something I'm afraid that we're going to have to learn to live with," he added.

Climate change and increase in ticks impact wildlife

A biologist with the Ontario Federation of Anglers and Hunters said the changing climate and an increase in the tick population is also a growing concern for some wildlife in the Thunder Bay area.

The tick-borne disease impact on wildlife is low, but some species like wolves, coyotes and birds can be affected.

Matthew Robbins, a Fish and Wildlife Biologist with the Ontario Federation of Anglers and Hunters, explained that animals like deer and moose are more affected by ticks as a parasite, which can impact their survival rate.

"Especially in high tick years, which are becoming more and more common, fawns are found with just infestations around their eyes and they're blind, or just very weak because of blood loss and things like that," said Robbins.

Robbins said the "explosion" of winter tick population due to the changing climate is more of a threat for animals like moose in the Thunder Bay area, especially the moose calves.

"It's really an awful sight to see," said Robbins. "If you get a moose calf, it can be covered in thousands, hundreds of thousands of these winter ticks. And it can become so weakened by the blood loss that it dies or becomes very vulnerable to other stressors or risks."

Robbins said hunters can report tick-infested animals to the Ministry of Natural Resources, or to the Canadian Wildlife Health Cooperative.

Officials are recommending people thoroughly check clothing, skin, and pets for ticks from the start of spring through the fall.

More information about identifying ticks and preventing bites can be found on the Thunder Bay District Health Unit website.

If a blacklegged tick is found, the health unit recommends people call (807) 625-5900 or toll-free at 1-888-294-6630 to speak with a public health inspector.