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

This story is part of CBC Health’s Second Opinion, a weekly analysis of health and medical science news emailed to subscribers on Saturday mornings. If you haven’t subscribed yet, you can do that by clicking here.

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.”

Patchwork surveillance for tick-borne illnesses

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. 

Since then, human cases have shot up. While there were only a few hundred country-wide infections identified in the first few years after provinces started reporting data, the annual count in recent years regularly hit more than 2,500, likely due to both increased awareness and higher numbers of bacteria-carrying ticks.

Numbers are hazier, however, for tick-borne pathogens like Powassan, which is known for causing life-altering neurological symptoms and brain inflammation in roughly 10 per cent of cases. 

That viral infection, along with the bacterial infections anaplasmosis and babesiosis, was recently deemed nationally notifiable — but hard data from the provinces remains hard to come by.

Canada’s first locally recorded case of anaplasmosis was back in 2009 in Alberta. For more than a decade afterwards, Manitoba was the only province tracking its spread, while some others, including Ontario and Nova Scotia, followed suit last year by broadening out their tracking beyond just Lyme disease.

In 2023, Ontario had 40 confirmed or suspected anaplasmosis cases, the majority occurring from June to August, plus 15 cases of babesiosis. Both infections can cause flu-like symptoms, or more serious illness. (Manitoba’s figures suggest there are just a handful of infections in any given year, including few if any cases of babesiosis.)

But those provincial figures don’t capture the full situation.

WATCH | Insect-borne infections on the rise, thanks to climate change:

Insect-borne infections on the rise thanks to climate change

Diseases carried by insects that infect humans, like Lyme disease and West Nile virus, are on the rise in Canada. The shorter, less severe winters due to climate change have allowed those insects to expand their range.

“We are seeing a lot more victims, especially in those high-tick areas, specifically if you’re looking at Ontario, Quebec, and Nova Scotia,” said Heather Coatsworth, one of the Public Health Agency of Canada’s (PHAC) top tick experts, in an interview with CBC News.

Coatsworth, the chief research scientist for the National Microbiology Laboratory’s field studies section, said there are now “hundreds and hundreds” of anaplasmosis infections occurring across the country every year, along with “sputtering” reports of babesiosis.

As for Powassan — named after the Ontario town where it was first discovered in a young boy who died of his illness back in 1958 — infections remain rare and localized to certain regions, Coatsworth noted. 

What’s concerning, she added, is that the virus transmits through tick bites in as little as 15 minutes, and is a “much harder hitter” when it comes to human symptoms.

New U.S. surveillance data, published in the journal Clinical Microbiology and Infection in June, also shows a four-fold spike in the number of American cases, partially thanks to the broader spread of the black-legged ticks that carry both Powassan and Lyme. From 2004 to 2013, 64 human Powassan cases were reported to U.S. officials, but that tally jumped to nearly 300 cases in the decade after.

A similar spike in Canada isn’t out of the question, given rising annual temperatures that are providing ticks more warm days to circulate far beyond their historic habitats.

“Climate change is the main driver,” Coatsworth said, noting that the increased range of ticks means these various health threats are now appearing in more animal species and urban, downtown areas.

“And once those pathogens get to a higher level, they kind of spill over naturally into the human population.”

Prompt treatment can be crucial

Despite spiking case counts of these lesser-known infections, limited awareness means a growing cohort of patients may face hurdles in getting a diagnosis and treatment.

Many health-care providers aren’t yet aware that these infections even exist, which can mean medical teams don’t always conduct the right diagnostic tests, warned Bogoch, the infectious diseases specialist in Toronto.

Those delays matter given the time-sensitive nature of tick-borne illnesses, which aren’t yet preventable through any approved vaccines.

When it comes to bacterial infections, prompt antibiotic treatments can be crucial to ensure someone’s infection doesn’t progress into dangerous territory. (In some cases, mild illness resolves on its own. There’s also no specific treatment for Powassan virus, but rather supportive care to manage its range of symptoms, including pain control for headaches, or rehydration for vomiting.)

Ottawa-area resident Mary Raths considers herself lucky for getting a prompt anaplasmosis diagnosis and treatment when she fell ill with a headache, nausea, and fever, not long after a camping trip in 2021. 

Raths first tested herself for COVID-19, and when that came back negative, she went to a nearby hospital. After being admitted, she soon felt like “one of those mystery patients.”

“They did so many tests…. I don’t even remember a lot of the things they did, because I was that ill, but they did so many different blood tests, they did X-rays, they did a CT scan,” she recalled.

Thankfully, said Raths, her attending physician had previously treated an anaplasmosis patient and knew to consider the tick-borne disease. Within 24 hours she was given heavy-duty antibiotics as a precaution, and after five days in hospital, she ended up making a full recovery. 

It wasn’t until later on that blood tests confirmed she had indeed caught the bacterial infection, likely from a tick bite on her recent camping trip. 

“They made their best guess, and treated me for that, and confirmed it later,” she explained. “If I hadn’t recovered so quickly, it would’ve been scary.”

‘We’re behind the 8-ball’

Not all patients are that fortunate, and limited awareness remains a challenge, Bogoch stressed. “We’re behind the 8-ball,” he said, “and we definitely have a lot of catching up to do.”

In a statement, PHAC told CBC News a new national tick-borne disease surveillance dashboard is under development and could be up-and-running by this fall. It’s meant to give Canadians a picture of case counts over time, broken down by geographic, demographic, and seasonal factors, with a focus on Lyme disease. 

But the first provincial data for that trio of additional infections — anaplasmosis, babesiosis, and Powassan — isn’t expected until summer 2025, the agency said.

Timing aside, Coatsworth is hopeful that more data-sharing will give Canadians a better sense of where they’re most at risk, so people can try to prevent tick bites from happening in the first place.

“As you enjoy the outdoors, it’s probably going to be a new reality,” she warned.

WATCH | Ontario tracking 3 more tick-spread diseases:

Ontario is now tracking three additional tick-borne illnesses

A warming climate means a greater tick population and more tick-borne illnesses in Canada. Ontario already tracks cases of lyme disease, but starting now, it will also track three other tick-borne illnesses, including anaplasmosis, babesiosis and powassan virus disease.

A life cut short

That reality is one de Lint hopes others won’t have to face, given the suffering and high level of paralysis his wife endured following her Powassan infection. The couple doesn’t even know where she got bit, he added, since Harris hadn’t spent time beyond their own Ottawa neighbourhood leading up to her illness.

“I really hope that doctors, especially the ER docs, are more educated and given more data and information so they can recognize this kind of thing when it comes across them,” he said. 

The Ottawa resident recounted four decades of memories with Harris, prior to her illness. From the couple’s meet-cute while de Lint was working in a record shop and Harris was searching for a mandolin player, to “years and years” of playing music together, to their longtime creative collaborations through Harris’s work as an artist and de Lint’s career as a writer and novelist — all of it, he said, was cut short.

“It was terrible what happened to MaryAnn, but she had 70 years,” de Lint added. “Imagine this happening to a kid? Their life would be over.”