Tick season has begun across much of Canada, bringing with it the threat of Lyme disease.
Just a few decades ago, Lyme disease was pretty well unheard-of in Canada. But climate change and other factors have facilitated a growing number of cases in the last few years.
“It’s spreading geographically, so there’s more of Canada affected,” said Nick Ogden, a research scientist and director of the public health risk sciences division with the National Microbiology Laboratory. “But behind that, the seasons are longer, the numbers of ticks are increasing and the proportion that are infected is increasing.”
There were 2,025 Lyme disease cases in Canada in 2017 – the latest year for which public data is available. This is a huge jump from the mere 144 cases reported in 2009.
Health Canada did not provide updated Lyme disease numbers by print deadline, though Ogden said that there has been a general upward trend in the number of cases.
There are a number of reasons for this, he said, including greater awareness among patients and physicians, longer active seasons for ticks and more ticks in more places around Canada.
According to Health Canada, black-legged ticks are found in many parts of the country now, from Vancouver Island to Winnipeg, to southern Quebec, to New Brunswick and Nova Scotia.
In Ontario, “We’re seeing more black-legged ticks — we’ve also seen the spread of them into areas of the province,” said Curtis Russell, a senior program specialist with Public Health Ontario.
Ticks can expand their range by about 20 to 40 km per year, Russell said, though because ticks prefer wooded areas, he thinks it’s usually a bit slower than that. However, even outside of established tick areas, because migratory birds carry ticks from place to place, you could technically encounter a tick anywhere in Ontario, he said.
Birds are just the first step in tick migration, Ogden said. Birds bring the ticks north, and if there is a suitable environment with lots of tasty mammalian hosts nearby, they can settle in and reproduce.
So, you get more ticks, he said.
And as they reproduce and feed on local wildlife, more and more of them end up carrying the bacteria which causes Lyme disease — Borrelia burgdorferi.
So over time, a higher proportion of ticks end up becoming potentially harmful to humans.
Near Ogden’s home in southern Quebec, he said, eight years ago hardly any of the newly-arrived ticks carried the Borrelia bacteria. “But now, in some areas in that wood, 35 per cent of ticks are infected.”
Ticks love to live in brushy, wooded areas with lots of leaf litter, Russell said. They’re vulnerable to drying out, so when it gets too hot, they’re able to take shelter in the shade or in leaves on the forest floor.
Ticks hang out on leaves, grass, branches and the like, waiting for a suitable animal to brush past, so they can hop on. You don’t want to be this animal.
Staying in the middle of the trail can help you to avoid brushing up against a tick, Russell said. Similarly, wearing long-sleeved shirts and long pants in a light colour can ensure that ticks don’t immediately reach your skin if you do pick one up, and makes them easier to spot against the light background.
Wearing an insect repellent containing DEET or icaridin (sometimes called picaridin) can also help keep ticks away, Russell said. Some kinds of permethrin pre-treated clothing were also recently approved for use in Canada.
When you get home, Russell recommends placing your clothes in a hot dryer for 60 minutes, taking a shower, and doing a careful “tick check” – examining yourself for any ticks.
Ticks are extremely small: adult ticks are about the size of sesame seed, and nymphs are the size of a poppy seed.
If you do spot a tick, remove it carefully using tweezers, Ogden said. (A good instruction guide is here.) You can save the tick to show it to a health-care provider later if something happens, or you can take a photo and submit it to an online surveillance program like eTick, where experts will tell you what species it is, and what your risk might be.
Removing a tick quickly gives it less of a chance to potentially pass on an infection, Ogden said.
If you feel sick or develop a rash, Russell recommends visiting a health-care provider and telling them that you were bitten by a tick. Early Lyme disease can be treated with antibiotics, but it can become more serious if left untreated.
However, both Ogden and Russell note that you shouldn’t let the fear of ticks keep you from going outside.
“As long as we’re allowed to go out, it’s good to go out,” Ogden said. “Staying in and not doing outdoor activities is not good for your health. And that’s why it’s important to be aware of ticks and how to protect yourself from tick bites.”
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