Tick-spread illnesses are on the rise in Canada. Are surveillance, awareness efforts keeping up?

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One morning in Sept. 2021, MaryAnn Harris felt strangely tired. She told her husband, Charles de Lint, that she needed to lie down. Then more worrisome symptoms began cropping up, from nausea to double vision.

The Ottawa couple rushed to a local emergency department. 

At first, the cause of Harris's ailment was a mystery. The ER team ran various tests, and after a few hours with no answers, they sent her husband home due to visitor restrictions put in place during the pandemic.

By the time de Lint came back the next day, his beloved partner of four decades was unresponsive and on life support in the intensive care unit.

"You don't know what to think, what to feel," de Lint recalled. "It was just utter panic."

What followed was a three-year ordeal, as medical teams offered a battery of tests and treatments in hopes of bringing Harris back from the brink of death. She eventually regained consciousness, but by that point, inflammation in her brain stem had left her paralyzed. Harris never left the hospital and died in early June at the age of 71.

The cause of her devastating illness? A little-known virus that spreads through tick bites.

For years, medical experts have warned a rising number of Canadians are being exposed to ticks carrying an array of dangerous pathogens. Lyme disease is the most familiar — and by far the most common — but there's growing concern about lesser-known threats as well, from various bacterial infections, to the rare Powassan virus that claimed Harris's life earlier this year.

Case counts are rising, yet data remains thin, all while climate change is helping tick populations spread further north, putting even more of the population at risk. The question now, experts say, is whether awareness and surveillance efforts are keeping up with a growing threat.

"There's probably still more of [these infections] than what's being diagnosed … because the general public is probably not that aware of it, and healthcare providers aren't aware of it," said Dr. Isaac Bogoch, an infectious diseases specialist with the University Health Network in Toronto.

"The more you look, the more you find."

Actually finding evidence of these emerging health threats is a tricky business, given the patchwork approach to tracking various tick-spread diseases in Canada.

Lyme disease, a potentially serious illness spread through black-legged ticks, has been nationally reportable in Canada since 2009.