Tick Trouble

When humans encroach on areas where ticks and small mammals or deer live then there's greater potential for people and ticks that carry disease to come into contact. (Dawn Villella/Associated Press)

Lyme disease cases are on the rise in Canada as ticks that carry the disease advance into new areas, public health officials warn.

Health officials want people to take precautions against ticks that carry Lyme disease, which are increasing their range.

The ticks pick up bacteria from feeding on rodents or deer and can pass on the bacteria to humans.

The Public Health Agency of Canada says that in 2012, there were 315 cases of Lyme disease in the country. The final numbers for 2013 aren’t in but are expected to be about 500. The agency predicts 18,000 cases by 2020.

Health officials recommend that Canadians be aware of the risks of Lyme disease and take precautions where there’s potential for ticks:

  1. Cover up with light-coloured clothing to spot ticks more easily.
  2. Wear closed-toed shoes.
  3. Tuck your pant legs in to your socks to prevent ticks from crawling up your legs.
  4. Tuck your shirt in to prevent ticks from getting on to your skin.
  5. Use insect repellents that contain DEET or Icaridin.
  6. Shower or bathe within two hours of being outdoors to wash away loose ticks.
  7. Do daily "full body" checks for ticks on yourself, your children and your pets.
  8. If you find a tick on your skin, remove it within 24 to 36 hours.

More cases may be partly a result of increased awareness and testing, said Dr. Frank Atherton, Nova Scotia's  deputy-chief medical officer of health.

"I expect the numbers will go up, they won't shoot up," Atherton said.

Role of warmer temperatures

It’s important to plan for tick-borne illnesses such as Lyme disease, Atherton said. Climate change is a factor in the spread of "zoonotic diseases" that primarily affect animals and can cross over to humans, he said.

"Warmer temperatures permit the ticks to be established in new areas where previously it may have been too cold for them to survive in the past," said Amy Greer, who holds a Canada Research Chair in population disease modelling at the University of Guelph.

Greer has studied how ticks are expanding northward from the U.S. border into the most heavily populated areas of Canada.

The tick needs to be attached for about 36 hours on average, Greer explained. "If you can find the tick and remove it before that point in time then the risk … you would become infected is very slim."

Based on her research in the U.S., Greer points to human population density, increased urbanization and underreporting as other explanations for the projected increase in Lyme diseases cases in this country.

Wooded areas are the best habitat for ticks, Greer noted.

For Ingrid McAdam, 50, of Dartmouth, N.S., it took 2½ years after the discovery of a tick embedded in a lump in her elbow to be diagnosed with Lyme disease. She initially had symptoms such as a rash and sharp pain in her eye.

"I had sore joints, sore muscles," McAdam recalled. "My brain went from a 45-year-old working brain to an 85-year-old brain basically overnight."

Antibiotics have helped, but she still has cognitive issues.

With files from CBC's Pauline Dakin and Amina Zafar