Quirks & Quarks

As climate warms and tick populations grow, Quebec turns to science to combat rising rates of Lyme disease

Warmer weather conditions allow disease-carrying ticks to reproduce faster while gradually migrating north by hitching rides on their hosts — mice, birds, deer and other animals, including humans. As a result, Lyme disease has become a far more pressing public health issue in parts of Quebec than it has ever been before.

Researchers are mobilizing to track and control Lyme-carrying ticks and their hosts

As the climate warms, researchers are concerned that tick populations are being established in areas where they've never been a problem before. Lyme disease is carried by ticks. (AFP/Getty Images)

This is the fourth in a series of Quirks & Quarks stories on how science and technology are working in regions and communities across Canada facing unique challenges of climate change. 

Public health officials in Quebec are concerned about how climate change is opening the door to new insect-borne illness like Lyme disease.

Lyme disease is carried by ticks, and as the climate warms, tick populations are being established in parts of the province where they've never been a problem before. 

The key for ticks to survive and thrive is temperature and the duration of consecutive warm days during their two-year life cycle, said Dr. Nick Ogden, a veterinarian and public health expert. 

"It's the amount of warmth in spring, summer and autumn. And that has increased quite noticeably in recent decades," said Ogden. 

When he's not putting pandemic plans into place for COVID-19, Ogden heads a research team at Health Canada that looks at how climate change impacts animal-borne diseases.

One of the team's key research areas is Lyme disease, in particular the blacklegged tick, Ixodes scapularis, that's responsible for spreading Lyme disease in Quebec. The blacklegged tick has historically been found farther south, in the East and Midwest of the U.S.

Longer, warmer summers have increased the rate of tick reproduction. (Submitted by eTick)

Ogden said warmer temperatures contribute to increasing numbers of ticks in Quebec. Longer, warmer summers have increased the rate of tick reproduction, and thus the number of ticks that can potentially carry disease. 

According to Virginie Millien, an assistant professor at McGill and curator of zoology and paleontology at McGill's Redpath Museum, warmer temperatures also benefit one of the tick's most important hosts, the white-footed mouse, which has expanded its range northwards, and outcompeted other mice.

The result is that Lyme disease has become a far more pressing health issue in southeastern Canada than ever before.

Virginie Millien, in the basement of McGill's Redpath museum, is an assistant professor at McGill and curator of zoology and paleontology at the museum. (Ellen Payne Smith/CBC)

Increase in Lyme disease cases

In Quebec alone, there were 338 Lyme disease cases contracted locally in 2019 — 115 more than the year before. Back in 2004, there were only two reported cases — and those people contracted the bacteria outside of Quebec.

It's an issue in other parts of the country as well. Federal public health data collected from the provinces found that reported Lyme disease cases increased from 144 in 2009 to 992 in 2016. (Data from 2018 shows 1,487 reported cases, but that number also reflects updated — and more flexible — ways of diagnosing Lyme disease cases.)

Not every tick bite will infect you. But if you do contract Lyme, it can cause terrible illness. If untreated, severe symptoms can last months — even years. These can include intense headaches, rashes, neurological and cognitive issues, arthritis and even heart disorders. 

Mélissa Laporte-Parenteau learned that first hand. Growing up in Quebec she had never heard of Lyme disease, but in 2017, she contracted the bacteria while camping in upstate New York.

"It was a Saturday morning. I was lying in my bed and my husband was there with me and he saw that under my armpit and on the side of my chest, I had like a big red spot and there was like a red bulls-eye rash, and we never saw something like that."

She had the characteristic "bulls-eye" rash, and other symptoms, including back pain. 

The 'bulls-eye' shaped rash can be a marker of Lyme disease. (Centers for Disease Control)

Laporte-Parenteau was lucky. Her infection was caught quickly and treated successfully. However, when Lyme disease lingers, it can potentially wreak havoc on multiple systems in the body. 

But Lyme disease is bad news not just for the patients who suffer serious symptoms, but for Quebec in general. That's because the disease risk is highest in places like the municipality of Bromont, in the Estrie, a region in the Eastern Townships, Quebec's tourist playground famous for summer and winter outdoor activities.

Why are ticks spreading to cities across Canada

3 years ago
Duration 2:34
They may be incredibly small but ticks can cause some serious health issues. Cases of Lyme disease have doubled in Canada within a year. We look at the threat and tips you need to know to protect yourself.

Dr. Cécile Aenishaenslin, an assistant professor at the University of Montreal and veterinary epidemiologist who specializes in public health, said there were so many cases in the small city of Bromont, about 90 kilometres southeast of Montreal, the community sought additional support beyond what local public health authorities were already doing.

"They were concerned, the municipality, that this would impact their own way of life and their economy," said Aenishaenslin.

'Small tick killers'

Together with public health, she and her team developed a two-year pilot project to reduce the risk of Lyme infections. Part of the plan is to reduce the numbers of blacklegged ticks, but not by going after the ticks directly. Instead, they're targeting the mice that carry the ticks.

Their strategy is to medicate wild mice with an acaricide, or tick pesticide, similar to the kind some people give their dogs.

"We mix it with peanut butter, and we put this in small boxes that are used to control rodents," she said. The mice eat the mixture, which isn't harmful to them. But when they venture into the woods and get ticks on them, "they will act like small tick killers," said Aenishaenslin.

Tracking ticks to prevent rise in Lyme disease

4 years ago
Duration 3:00
The risk is still relatively low and experts say the threat of Lyme disease shouldn't keep you from going outdoors — but they do have tips on how to avoid ticks.

But measures to reduce the number of ticks will only go so far. They also need to convince people to develop new behaviours, such as checking themselves for ticks and using insect repellents.

Humans are also a part of the Lyme disease system, and our best defence against this emerging infectious disease is prevention. That means changing our habits.

In order to cope with ticks, some people in Bromont have stopped going outside as much with their families, or even letting their kids play in the yard, said Aenishaenslin.

That strategy that comes with big downsides, including the health risks of inactivity, said Nick Ogden.

But the people who live and work in Lyme disease hotspots can also hope for some help from citizen scientists.

Tracking ticks

Jade Savage is an entomologist and professor at Bishop's University, in Sherbrooke, Que. She and her colleagues are having success detecting and tracking ticks using photos sent to them by members of the public.

Jade Savage, an entomologist and professor at Bishop's University in Quebec, tracks ticks using photos sent to them by the public. (Ellen Payne Smith/CBC)

With support from Quebec public health authorities, Savage launched an online tick recognition platform called eTick in 2017. Using either its website or mobile app, people can upload photos of ticks for a researcher to identify. If the tick is found on a person, they'll respond within 24 hours. 

The platform has become a model for other jurisdictions, including Nova Scotia, Newfoundland, Saskatchewan and Manitoba.

"It can be seen as a Tinder for ticks because there's pictures," said Savage. "Some people don't like to look at them, but I often encourage people to actually look at the pictures and some of these ticks are quite pretty. We always see the picture of this blacklegged tick with its evil looking long palps and, and it's been demonized quite a lot."

The eTick platform provides an important service to the public, but it also generates invaluable surveillance data. It shows researchers where tick populations are growing, and where they're moving to. And already they've moved pretty far.

The northernmost place a tick has been documented in the province using eTick is in Baie-Comeau, around 420 kilometres northeast of Quebec city.

We have to look carefully and try and identify which bugs might emerge ... so that we are ready for them.- Nick Ogden

Nick Ogden said that when he and his colleagues first started investigating Lyme disease, "there were only one or two tick population to know and, and they were in Ontario."

His modelling has shown it's possible that by 2080, ticks will have journeyed 1,000 kilometres north. 

As the climate changes, other zoonoses — diseases that jump from animals to humans — may also emerge, said Ogden. 

"We have to look carefully and try and identify which bugs might emerge, why they might emerge, and when in the future they might emerge, so that we are ready for them." 

Written by Brandie Weikle and Ellen Payne Smith. Produced by Ellen Payne Smith.

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