Skip to main content

Climate change allows these biting bugs to multiply even more, reach new places, infect more people with Lyme disease – and then endure the milder winters before starting the cycle again. Here’s what you can do to stay safe

Katie Stevenson stands with her four-year-old daughter and their rescued hens in Digby, N.S., where they live. The hens were introduced to prey on the abundant ticks on their property.Carolina Andrade/The Globe and Mail



Until Katie Stevenson moved from PEI to Digby, N.S., in the fall of 2019, she’d never even seen a tick. But since the spring, the ticks on their rural two-acre property have become so abundant, she’s had to restrict where her children play and resorted to buying six hens, which eat the eight-legged arthropods, to help tame the population in her yard.

But the family’s most traumatic encounter with black-legged ticks (also known as deer ticks) happened an hour away, in Yarmouth. Ms. Stevenson’s husband and four-year-old daughter went for lunch at a Wendy’s before walking through a patch of cut grass beside the parking lot. Later that evening, Ms. Stevenson was brushing her daughter’s hair when she felt what she thought was a scab on the top of her head.

“It was the tiniest tick I’ve ever seen,” Ms. Stevenson says – the size of “a couple of eyelashes.”

Following the government’s recommended guidelines for tick removal, she grabbed a pair of tweezers, pinched close to the tick’s head and tried to pull it straight out.

“It immediately broke,” she says. “And then it actually got sucked down into her head, or it had enough life to squirm back down.”

Fearing her daughter could be infected with Borrelia burgdorferi – the bacterium that can cause Lyme disease – she placed the partial tick in a plastic bag, and took it and her child to the hospital.

While waiting to see the doctor, Ms. Stevenson took a closer look and noticed a second, larger tick attached to the skin behind her daughter’s ear. The girl was treated with the antibiotic doxycycline, but for the next year, she has to be monitored for symptoms of Lyme disease, including unusual fatigue and muscle pain.

This has been become an increasingly familiar routine for Canadians.

“As our climate is getting warmer, the range of the ticks that cause Lyme disease is expanding northward,” says Dr. Lori Burrows, a professor of biochemistry and biomedical sciences at McMaster University in Hamilton.

“So 20 years ago, we really didn’t have a problem to the extent we do now – but it’s getting worse and worse.”

Deer ticks, also called black-legged ticks, are one of the species that commonly bites people in Canada.Stegerphoto/Getty Images

Coming into this summer, researchers are seeing an explosion of ticks that could spell big trouble as Canadians, fed up after months of lockdowns and restrictions, plunge into the great outdoors.

But ticks don’t only affect campers and other adventurers – not any more. Climate moderation, coupled with changes in land use (like farmland to forest), have fuelled the tick’s rise in a couple of ways. They’ve improved survival rates among host animals, particularly deer and mice, which thrive in urban areas (They’re also found on groundhogs and coyotes.)

Milder temperatures mean more of the parasitic arachnids, which have a two-year life cycle, are surviving Canadian winters and staying put year-round.

And they’re spreading.

In recent years, the majority of Lyme disease cases were reported in Nova Scotia, Ontario and Quebec. Nonetheless, “you cannot say with certainty, ‘You will not encounter a tick in this place in Canada’ – it’s just greater or lesser risk,” says Dr. Vett Lloyd, a professor of biology at Mount Allison University in New Brunswick who studies ticks and zoonotic diseases.

Cases of Lyme disease, the most common tick-borne disease, have increased rapidly over the past decade, from 144 in 2009 to 2,636 preliminary cases in 2019, the most recent year for which the Public Health Agency of Canada (PHAC) has data. And according to Kirsten Crandall, a joint PhD candidate who researches ticks and infectious diseases at McGill University and the University of Ottawa, cases of reported Lyme disease can be used as a proxy for the growth of tick populations.

Lyme disease in Canada

From 2009–2016

No. of cases

Incidence per 100,000 people

3.0

1,000

2.5

800

2.0

600

1.5

400

1.0

200

0.5

0.0

0

2009

2010

2011

2012

2013

2014

2015

2016

THE GLOBE AND MAIL, SOURCE: health canada                

Lyme disease in Canada

From 2009–2016

Number of cases

Incidence per 100,000 people

3.0

1,000

2.5

800

2.0

600

1.5

400

1.0

200

0.5

0.0

0

2009

2010

2011

2012

2013

2014

2015

2016

THE GLOBE AND MAIL, SOURCE: health canada                

Lyme disease in Canada

From 2009–2016

Number of cases

Incidence per 100,000 people

3.0

1,000

2.5

800

2.0

600

1.5

400

1.0

200

0.5

0.0

0

2009

2010

2011

2012

2013

2014

2015

2016

THE GLOBE AND MAIL, SOURCE: health canada                

Lyme disease by province

2016

Probable (left scale)

Incidence (right scale)

Confirmed (left scale)

Number of cases

Incidence per 100,000 people

40

400

35

350

30

300

25

250

20

200

15

150

10

100

5

50

0

0

B.C.

Alta.

Sask.

Man.

Ont.

Que.

N.B.

N.S.

PEI

NL

THE GLOBE AND MAIL, SOURCE: health canada

Lyme disease by province

2016

Number of cases

Incidence per 100,000 people

40

400

Probable (left scale)

35

350

Confirmed (left scale)

Incidence (right scale)

30

300

25

250

20

200

15

150

10

100

5

50

0

0

B.C.

Alta.

Sask.

Man.

Ont.

Que.

N.B.

N.S.

PEI

NL

THE GLOBE AND MAIL, SOURCE: health canada

Lyme disease by province

2016

Number of cases

Incidence per 100,000 people

40

400

35

Probable (left scale)

350

Confirmed (left scale)

30

300

Incidence (right scale)

25

250

20

200

15

150

10

100

5

50

0

0

B.C.

Alta.

Sask.

Man.

Ont.

Que.

N.B.

N.S.

PEI

NL

THE GLOBE AND MAIL, SOURCE: health canada

It only takes the identification of one black-legged tick for an area to become a designated Lyme disease “risk area,” which covers a 20-kilometre radius from where the tick was first identified. There are now 60-odd such areas across six provinces, including all of Nova Scotia, Vancouver Island and heavily populated urban regions in Ontario including Peel, York, Niagara, Ottawa and Toronto, where infectious black-legged ticks have been found in several city parks.

In previous decades, migratory birds were the primary vehicle for tick migration, and ticks can still be carried on birds and mammals to parts of the country that aren’t classified as risk areas. One female tick lays about 3,000 eggs.

In the Prairies, ticks are migrating from the U.S. and establishing populations. There’s a “serious problem” in southern Manitoba, Dr. Lloyd says, where Lyme disease is considered endemic. The number of confirmed cases in the province more than doubled between 2015 and 2019, according to provincial public health data.

Most risk areas are along the border, where the winters are milder – and where most Canadians live. Peak season is spring and fall, and tick activity also increases in the hot periods of summer, toward the end of June and into July. They need moisture to survive, so when it’s hot, they can often be found in areas with moist leaf litter, like brushy, wooded spots, and in deciduous or mixed deciduous forests.

“People really need to realize these ticks are extremely small,” says Dr. Curtis Russell, a senior program specialist with Public Health Ontario.

“We don’t get many black-legged tick submissions in the middle of the summer because people don’t notice them.” But that’s when they see most human cases of Lyme disease.

Ticks that carry Lyme disease in Canada

There are two types of ticks that carry Borrelia burgdorferi, the

bacteria that cause Lyme disease in humans: the black-legged

or deer tick, found in southern and eastern Canada, and the

western black-legged tick, found in the West. They go through

a two-year life cycle. The ticks can become vectors of the Lyme

disease-causing bacteria after feeding on infected birds or

rodents. Humans often contract the disease after being bitten

by tiny ticks in the nymph stage. To prevent disease, ticks

should be removed within 48 hours.

Black-legged or

deer tick

(Ixodes scapularis)

Western

black-legged tick

(Ixodes pacificus)

Relative sizes

Adult

female

Adult

male

Nymph

Larva

1 cm

Ticks that carry Lyme disease in Canada

There are two types of ticks that carry Borrelia burgdorferi, the bac-

teria that cause Lyme disease in humans: the black-legged or deer

tick, found in southern and eastern Canada, and the western black-

legged tick, found in the West. They go through a two-year life cycle.

The ticks can become vectors of the Lyme disease-causing bacteria

after feeding on infected birds or rodents. Humans often contract

the disease after being bitten by tiny ticks in the nymph stage.

To prevent disease, ticks should be removed within 48 hours.

Black-legged or

deer tick

(Ixodes scapularis)

Western

black-legged tick

(Ixodes pacificus)

Relative sizes

Adult

female

Adult

male

Nymph

Larva

1 cm

Ticks that carry Lyme disease in Canada

There are two types of ticks that carry Borrelia burgdorferi, the bacteria that cause Lyme

disease in humans: the black-legged or deer tick, found in southern and eastern Canada,

and the western black-legged tick, found in the West. They go through a two-year life cycle.

The ticks can become vectors of the Lyme disease-causing bacteria after feeding on infected

birds or rodents. Humans often contract the disease after being bitten by tiny ticks in the

nymph stage. To prevent disease, ticks should be removed within 48 hours.

Black-legged or

Deer tick

(Ixodes scapularis)

Western

black-legged tick

(Ixodes pacificus)

Relative sizes

Adult

female

Adult

male

Nymph

Larva

1 cm

Young ticks are about the size of a poppy seed, while adults are roughly as big as a sesame seed. Only after they’ve been feeding for a while do they “end up looking like a giant, grey skin tag with legs sticking out,” Dr. Lloyd says. An important note about ticks, she adds, “is their idea of a good time is to feed for several days. And they’d prefer that you not notice them.”

Ticks transfer to humans through contact with vegetation, meaning bites can happen in gardens, playgrounds, soccer fields and residential areas.

“There’s nothing that would force a tick to stay in the woods,” Dr. Lloyd says. “They probably prefer it, but if it’s peak tick season – so the spring or the fall, when there are a lot of ticks out there looking for a meal – you’re more likely to encounter one in your backyard or on grass.”

In St. Eugene, in Eastern Ontario, where Isabel Deslauriers has lived for the past 10 years, she’d only ever seen one tick. But in the past few weeks, she’s had to remove four from her husband, who encountered the ticks while gardening. Though he was wearing long sleeves, two had crawled up his arm unnoticed, attaching themselves to the creases inside his elbows. Ms. Deslauriers says she learned how to remove the critters in Scouts and Guides, and through public awareness campaigns on social media.

“My husband had no idea – like, he never heard any of that. So if I hadn’t known, he would probably have just scratched it off,” she says. She now warns her neighbours and any visitors to their home about ticks, and stopped taking their cat outside on a leash.

Experts say routine tick checks are essential, but it’s important to know where to look. Ticks migrate to cracks and creases in the skin, like underarms, behind the ears and along the hairline – especially on children, whose heads are closer to the ground.

“Unless they’re incredibly hungry, they’re going to crawl to a part of your body that is dark and moist,” Dr. Lloyd says.

The longer a tick feeds on a human, the higher the risk of transmission for Lyme and other tick-borne diseases. In areas where populations of black-legged ticks are established, the number of those infected with Borrelia burgdorferi can be upward of 50 per cent. If a person is bitten by an infectious tick, the likelihood of transmission rapidly increases after 24 hours, nearing 100 per cent after 96 hours. There are other, rarer tick-borne illnesses, too, such as anaplasmosis and Powassan virus, which was first identified in Ontario and causes encephalitis, an infection of the brain. In those cases, transmission can occur in about 15 minutes.

Early signs and symptoms of Lyme disease

They usually start 3 to 30 days after you have been bitten by

an infected black-legged tick. Most people experience mild

flu-like symptoms soon after being bitten, while a small

number may have more serious symptoms, sometimes

weeks after the bite.

Headache

!

Fatigue

Chills

Swollen

lymph nodes

Rash Some

times shaped

like a bull's eye

Fever

Muscle and

joint aches

john sopinski and MURAT YÜKSELIR / THE GLOBE AND MAIL

SOURCE: GOVERNMENT OF CANADA; university of

rhode island

Early signs and symptoms of Lyme disease

They usually start 3 to 30 days after you have been bitten by an

infected black-legged tick. Most people experience mild flu-like

symptoms soon after being bitten, while a small number may have

more serious symptoms, sometimes weeks after the bite.

Headache

!

Fatigue

Chills

Swollen

lymph nodes

Rash Some

times shaped

like a bull's eye

Fever

Muscle and

joint aches

john sopinski and MURAT YÜKSELIR / THE GLOBE AND MAIL

SOURCE: GOVERNMENT OF CANADA; university of

rhode island

Early signs and symptoms of Lyme disease

They usually start 3 to 30 days after you have been bitten by an infected black-legged tick.

Most people experience mild flu-like symptoms soon after being bitten, while a small

number may have more serious symptoms, sometimes weeks after the bite.

Headache

!

Fatigue

Chills

Swollen

lymph nodes

Rash Some

times shaped

like a bull's eye

Fever

Muscle and

joint aches

john sopinski and MURAT YÜKSELIR / THE GLOBE AND MAIL

SOURCE: GOVERNMENT OF CANADA; university of rhode island

One notable symptom of early Lyme disease is a bull’s-eye rash. But experts warn that not every case begins with one, and besides, it’s not always easy to spot. Kris and Shannon Daugherty of Sarnia, Ont., might have missed the rash on their eight-year-old son’s ankle if it weren’t for the poison ivy he’d contracted while camping at Pinery Provincial Park, a designated risk area. His reaction to the ivy was so severe that they took him to the hospital, where a doctor spotted the bull’s-eye. Mr. Daugherty says his son had barely noticed the bite, “so we didn’t think anything of it.”

By the time the bite was discovered, the tick had fallen off. But diagnostic testing determined the boy had been infected with Lyme disease. He received medication quickly enough that it had no long-term effects.

“You have to wait six to eight weeks for the body to produce detectable levels of antibodies, and that kind of puts you outside that ideal treatment window,” says Justin Wood, founder and CEO of Geneticks, the first private tick-testing lab in Canada. Determining the species of tick and the presence of pathogens can better equip a person seeking treatment from their health care provider. (He says that ticks kept in sealed bags or containers in the freezer can be tested up to five years later.)

So with the notable increase in ticks and cases of Lyme disease, why isn’t the government taking action to control tick populations the same way they do for gypsy moths, for instance? Dr. Russell says it’s not that easy – spraying to control ticks would likely be ineffective.

“We’ve looked at what the U.S. has done,” he says. But some of the pesticides in use there haven’t been approved in Canada – and they don’t seem all the effective in reducing tick populations anyway, Dr. Russell says. In cases where the use of pesticides has cut tick populations, it didn’t necessarily lead to a reduction in the spread of bacteria or human cases.

Dr. Russell says the only areas where tick control might work is on a peninsula or island, where ticks infestations can be tamed through spraying in combination with deer barriers and culls, which prevent deer from bringing them into the area. Ontario, he says, is simply too vast for a program like that to be effective. “That’s why we tell people the two big things are personal protection and general tick awareness.”

A researcher at France's Institut National de la Recherche Agronomique studies a tick under a microscope in 2018.JEAN-CHRISTOPHE VERHAEGEN/AFP/Getty Images

In the early 2000s, a Lyme disease vaccine called Lymerix became available, but the manufacturer pulled it from the market in 2002. While the company that made it, SmithKline Beecham (now GlaxoSmithKline), cited insufficient consumer demand, Dr. Burrows says there was speculation the vaccine caused arthritis in certain patients – which likely wasn’t true.

“But it scared enough people off from getting the vaccine that it didn’t do very well when they tried to sell it, so they eventually just pulled it,” Dr. Burrows says, likening the situation to recent concerns about AstraZeneca’s COVID-19 vaccine causing blood clots.

But given the quick development of COVID vaccines, and the availability of a Lyme disease vaccine for dogs, some wonder why it’s taken so long for a human version to return to the market. Dr. Burrows says the likely reason is the high cost of human clinical trials and the difference in clinical standards for testing on animals compared with humans. But she stresses the need for a human vaccine is urgent.

In the meantime, Dr. Lloyd says we’ll just have to learn to live with ticks. “They’re not going away, but we can certainly live around them,” she says. But much like COVID-19, it will mean changing our behaviour in order to make us safer.

“Most people are repulsed by ticks,” Dr. Lloyd says. “They’re creepy, crawly bags of pathogens. There’s really not much to love about a tick. But we still need to go outside.”



People go for an evening walk along Quarry Rock in North Vancouver's Baden Powell trail.The Canadian Press

How to protect yourself from ticks

  • Stay on trails. Ticks don’t jump or fly, so human contact occurs through brushes with vegetation, like grass and leaves. Avoid these areas, along with heavily wooded and brushy areas, and familiarize yourself with Lyme disease risk areas.
  • Dress properly. Wear socks and closed-toe shoes, and tuck long sleeves and long pants into socks and waistbands when visiting risk areas. Light-coloured clothing can make it easier to spot ticks. After walking on a trail or other tick habitat, remove your clothing and have a bath or shower. If the tick hasn’t yet bitten, it can be washed off. Putting clothing in the dryer for an hour on high heat can also kill ticks.
  • Perform full-body tick checks. Ticks often crawl around before they bite, and they migrate to cracks, crevices and moist areas on the body. Take extra care to check behind the knees, in the creases of elbows, the underarms, groin and behind the ears. Also check along the hairline – especially on children, as their heads are closer to the ground. Using a buddy system can be helpful for checking hard-to-see areas.
  • Spray yourself. Use insect repellants such as DEET or wear clothing treated with permethrin when going outside.
  • Keep your grass short. Clear tall grasses and brush around homes and at the edge of lawns, remove leaf litter, and move children’s play sets away from wooded areas.
  • Build a barrier. Placing a metre-wide wood-chip or gravel boundary between lawns and wooded areas can keep ticks from migrating into recreational areas, as they avoid dry areas.
  • Get a hen. Both guinea fowl and hens eat ticks and can be used as a natural way of controlling tick populations on your property, depending where you live.

I got bitten by a tick. Now what?

Unlike a mosquito bite or bee sting, it’s unlikely you’ll even register a tick bite right away. “Ticks are sneaky and can go unnoticed,” says Dr. Katie Clow, an assistant professor at the Ontario Veterinary College at the University of Guelph who researches vectors and vector-borne zoonoses.

If you do get bitten, don’t panic. Not every black-legged tick carries Lyme disease, and even if it does, that doesn’t necessarily mean it will result in human transmission. If transmission of bacteria does occur, it also doesn’t mean a person will contract Lyme disease.

That said, experts recommend removing a tick within 24 to 36 hours to reduce the likelihood of bacterial transmission. Grab the tick as close to the skin as possible using clean forceps or tweezers. Slowly pull it straight out, without twisting, and try not to crush or break it. Don’t attempt to burn a tick or spin it, or use Vaseline or nail polish remover, as it can agitate the arthropod and prompt it to regurgitate bacteria into the wound. (If any part of the tick remains in the skin, try to remove it with tweezers. If that’s not possible, let the skin heal and consult your health-care provider.)

Wash both the bite area and your hands with soap and water, or disinfect with alcohol-based hand sanitizer.

Try to keep the tick in a sealed bag or container to bring to your health care provider for testing, and record the date of the bite. Photos of ticks found on humans and animals can be submitted to eTick.ca for identification, and private tick-testing services such as Geneticks can determine pathogens and deliver results within 48 hours. Drowning the critter in rubbing alcohol or freezing it for several hours will kill it.

If you develop an unexpected rash or fever after being in an area known to have ticks, health experts recommend calling a doctor. And though a bull’s-eye rash is a key indicator of early Lyme disease, and sudden rashes or fevers after visiting a tick-infested area could indicate a tick bite, many people never develop any symptoms – which is why experts say awareness and prevention are key.