Another effect of climate change may be crawling up your leg this summer as you frolic in the woods.
Scientists say our warming world is speeding the spread of ticks that carry potentially debilitating Lyme disease, CTV News reported.
Dr. Robbin Lindsay, of the Public Health Agency of Canada who specializes in zoonotic diseases, said the populations of the blacklegged ticks that carry Lyme disease (sometimes called the deer tick) are growing.
"I myself have been studying these ticks for over 20 years and we have seen a tremendous change in the range and expansion of these ticks," Lindsay said from the National Microbiology Laboratory in Winnipeg.
The blacklegged tick that carries the Lyme disease bacteria used to be largely restricted to the northeastern United States.
It's named after the town of Lyme, Connecticut, where a number of children came down with unexplained rheumatoid arthritis in the early 1970s. Researchers eventually linked it to deer ticks that inhabited the wooded areas where the kids played, identifying the bacteria in 1981.
Lindsay told CTV News that when he began studying for his PhD in 1989 the only known Canadian population of the ticks was in southern Ontario. They are now established in other parts of Ontario, as well as regions of Quebec, Manitoba, New Brunswick, Nova Scotia and southern British Columbia.
The ticks continue to spread, said Lindsay, but the prevalence of the Borrelia burgdorferi bacteria that causes Lyme disease remains low in Canada, ranging from 10 to 50 per cent in the insects.
"So the risk of Lyme disease is reasonably low right now," he said. "But as the ticks get more established, the infection rate will go up."
Canada has about 150 confirmed cases of the disease each year, he said.
The majority are in Ontario, which typically reports about 100 cases a year, the Toronto Star said.
Lyme disease can be stealthy. Tick bites are usually painless and most people won't even know they've suffered a bite unless they perform, as Lindsay suggests, a tick check after walking in the country.
And not all bites produce the telltale bulls-eye skin rash at the site, which if found means prompt treatment with antibiotics to prevent the disease and its long-term, sometimes life-changing symptoms such as arthritic joints, neurologic problems and fatigue.
[Related: Lyme disease: Symptoms to look for]
It can take three days to a month for symptoms of untreated Lyme disease to show up.
CanLyme, a research foundation on tick-borne infections, said it provides counselling and support for hundreds of Canadians who are refused clinical diagnosis each year.
The group said it supports a private member's bill by B.C. MP Elizabeth May, leader of the Green Party, to set up a national strategy on Lyme disease.
"This bill responds to the failure of existing guidelines to reliably detect and treat Lyme disease," CanLyme President Jim Wilson said in a news release.
"Current policies make access to treatment subject to confirmation by a flawed test, resulting in refusal of diagnosis to many people with Lyme."
Among those supporting May's bill is Marleen Meerkat, who suffered symptoms such as blinding pains and headaches for years before being properly diagnosed. Several rounds of antibiotics and even treatment from a U.S. specialist has not cured her completely.
"It is preventable," Meerkat told CTV News. "It's about $50 of antibiotics at the early stages and that's that."