A female deer tick (also known as a blacklegged tick) that transmits Lyme disease is seen under a microscope at the University of Rhode Island. (Victoria Arocho/Associated Press)

A growing number of Canadians will have to start checking themselves thoroughly for ticks that spread Lyme disease if climate change enables the insects to survive a northern climate, researchers warn.

In a study published in Monday's online issue of the Canadian Medical Association Journal, scientists documented how the territory of the blacklegged tick Ixodes scapularis, which transmits Lyme disease, is expanding east across the country.

Once limited to a corner of Lake Erie's shoreline in Ontario, migrating birds have carried the ticks through southern Quebec, Manitoba, northern Ontario, the Maritimes and parts of the Prairies, the researchers found.

"Projected increases in temperature with climate change are expected to permit and accelerate the expansion of I. scapularis into Canada," wrote Dr. Nicholas Ogden from the Public Health Agency of Canada in Saint-Hyacinthe, Que., and his colleagues.

Lyme disease is transmitted by ticks that suck on the blood of animal or human hosts. The disease starts with a skin lesion that expands. Left untreated, it can result in facial palsy, meningitis, heart problems, nerve damage and inflammation of the brain and spinal cord, the team said.

The ticks, which look like a small, flat watermelon seed, live in tall grasses.

Ticks have built-in painkiller

The insects can bore into the body without being noticed, said entomologist Peter Heule of the Royal Alberta Museum in Edmonton.

"They do use a painkiller in order to prevent you from noticing when they've actually sunk in," said Heule. "They have a second feature there where they have spines on their mouth parts, and they can actually secrete a glue-like substance to cement themselves in until they're done feeding."

The ticks aim for warmer areas of the body, such as armpits, back of the neck and behind the ears, said Neil Haggart, an avid nature lover who grew up in the B.C. Interior and regularly checks for ticks.

Ogden's team urged doctors to be vigilant about signs of the disease and to treat it quickly.

Removing infected ticks from a person within 24 hours of attachment often prevents transmission, and early Lyme disease is usually easily treated with antibiotics, they noted.

As of this year, physicians will be required to report clinically confirmed and suspected cases of Lyme disease to the federal authority.

Combined with intensive field studies, the researchers hope to predict and then confirm how ticks are spreading in Canada, which should help doctors and public health officials target their public awareness programs where they are needed the most, the study's authors said.