Every year, Canada sees thousands of cases of Lyme disease pop up, and the numbers have increased in recent years. That may partly be due to climate change.

According to Public Health Ontario (PHO), Lyme disease is an infection transmitted through the bite of an infected black-legged tick.

"The majority of human cases occur due to exposure to areas known to have infected black-legged ticks," PHO notes. "Early symptoms may include fever, headache, muscle and joint pain, fatigue and an expanding red rash."

Sometimes this infection can get worse and spread to your nervous system, heart, and joints, resulting in severe symptoms such as facial palsy, shooting nerve pain, and Lyme carditis — an irregular heartbeat caused by Lyme disease. So far, there's no evidence that Lyme disease spreads from person to person or animal to person.

Like the rest of us, black-legged ticks love to come out in the summer months, but they can also be found in spring and fall. Per Health Canada, climate change has extended periods of over-zero-degree temperatures, giving black-legged ticks time to hang out longer and venture into once-tick-free areas.

Preventing Lyme disease

"The best prevention is to avoid tick bites by using insect repellent, wearing proper clothing, removing ticks as soon as possible after bites and removing tick habitats around the home," says Health Canada.

The agency also has a map highlighting all the places you might encounter black-legged ticks. It was last updated in 2022, so it's fairly recent and accurate.

Map of tick risk across Canada. Credit Health Canada.

The agency also says you must take caution, especially in grassy or wooded areas and while partaking in high-risk activities, such as hiking, golfing, hunting, fishing (from land), bird-watching, gardening, and camping.

If you work in parks, agriculture, or forestry, exercise a high degree of caution, too, and always screen yourself.

People who enjoy camping, hiking, and spending time outdoors in nature are more likely to be bitten by black-legged ticks and other bacteria-carrying insects.

But prevention is essential for all. A tick will not verbally ask if you're a hiker before it chomps down on your skin. If it does, you might have a bigger problem at hand.

For more information, check out Health Canada's guide on Lyme disease. Have a safe summer!