Lyme disease risk rises in Ontario as ticks spread

They’re small, hard to see, but they come with a big bite.

Black-legged ticks, otherwise known as deer ticks, are spreading across southern Ontario. They’re not just a harmless nuisance but some carry the Lyme disease bacteria that can wreak havoc on a person’s body.

As climate change takes an increasing toll on the environment, it’s also creating a breeding ground for the black-legged ticks. Ticks have a complicated life cycle, but they’re able to survive longer with average temperatures that are warmer.

“There is a suggestion that the current geographical range of those ticks could potentially expand in southern Ontario,” said Andrew Powell, manager of health protection programs with the St. Thomas Elgin Health Unit.

Although Elgin County and St. Thomas aren’t considered risk areas, the health unit is sandwiched between two other health units that do have risk areas within them — Chatham-Kent and HaldmandNorfolk.

The risk areas are determined by the tick submissions by each health unit.

A diagnosis of Lyme disease is complex. Current protocol in Canada does not recognize some diagnoses. So, some people who have been diagnosed using other protocols would not be included in those numbers.

Powell said projecting the risk of Lyme disease for the coming season is difficult.

As the range of hosts like mice, migratory birds and deer increase that leaves the possibility that the range of ticks will increase as well, Powell said.

“(Ticks) are able to move,” Powell said. “In southern Ontario in general I believe the risk is increasing over time especially with climate change.”

Generally, the spring and fall is when the adult ticks are active. The summer is when the younger, smaller ticks are active.

The health units don’t get as many calls during the summer months because people don’t see the ticks, said Curtis Russell, senior program specialist with Public Health Ontario.

“The general trend is we do see more black-legged ticks in Ontario and their populations are expanding. In certain areas we do see more of those ticks testing positive,” Russell said.