Cases of Lyme disease in Canada are dramatically rising as blacklegged tick populations grow and expand, say health officials who are urging the public to take precautions while enjoying the outdoors this summer.

With warm weather ushering in tick season, experts warn about the risks of infected ticks transmitting Lyme disease, a potentially debilitating infection that can result in heart problems, extreme fatigue and nervous system disorders.

The number of Lyme disease cases is at a record high and expected to keep growing. In 2017, there were 78 cases in Toronto, 987 in Ontario and more than 1,400 in Canada. By comparison, a year earlier there were 23 in the city, 388 in the province and 992 cases nationwide. But because it’s under-reported, some experts say the true number may be tenfold.

“The probability that someone would actually be exposed to a blacklegged tick in the early ’90s was very very low,” says research scientist Robbin Lindsay of the Public Health Agency of Canada, which began tracking Lyme as a nationally notifiable disease in 2009 with just 144 cases. “Now, the situation is very dynamic … The more we look, the more we find.”

In the 1990s, the only known risk area was Ontario’s Long Point Provincial Park. But with climate change, ticks are increasingly moving north from the United States, hitching rides on migratory birds. Now, they’re in Ontario, Quebec, New Brunswick, Nova Scotia, and have moved into Manitoba.

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“We definitely see westward movement of these ticks” says Lindsay, who works at the National Microbiology Laboratory in Winnipeg. “Undoubtedly, they’re going to end up in Saskatchewan in the very foreseeable future.”

In areas where ticks are more established, there’s a greater chance of their being infected with Borrelia burgdorferi bacteria, which causes Lyme disease. In Ontario, about 20 per cent to 25 per cent carry the bacteria, but in hot spots such as Long Point Provincial Park and Murphys Point Provincial Park, more than half are infected.

According to Public Health Ontario, their populations are expanding along the shores of Lake Erie, Lake Ontario and the St. Lawrence River and in the northwest. The agency releases an annual map showing the risk area for Lyme disease based on a 20-kilometre radius of where the ticks were found. This year, new additions to the map include Hamilton, Kenora and communities in the Simcoe Muskoka District Health Unit. Nearly all of Toronto and York Region, and half of Durham are at risk. But because ticks feed on migratory birds, they can show up outside the known risk areas, says entomologist Curtis Russell, a senior program specialist at Public Health Ontario.

“While the probability is low, people can find a tick almost anywhere in the province,” Russell says. But they need the right habitat to survive: wooded and brushy areas with lots of leaf litter and tall grass, where they wait for their next blood meal to pass by. “They don’t like short, short grass because it’s too hot for them. If someone is playing in the middle of a soccer field, it’s very unlikely that you’d find a tick there.”

In Toronto, tick populations exist in the east, in places such as Rouge Valley Park, Morningside Park and Highland Creek Park, and they’re moving west, says Dr. Christine Navarro, associate medical officer of health for Toronto Public Health. This spring, staff will look for them in 40 parks, conducting tick drags. She says she doesn’t want people to stay clear of city parks — just exercise some caution. After all, about 80 per cent of the city’s cases of Lyme disease last year weren’t contracted in Toronto, but when people were camping or cottaging in eastern Ontario.

“We definitely want people to go outside and enjoy the outdoors,” Navarro says. “If you’re going into a wooded and bushy area it’s important to plan ahead.”

The challenge with ticks is that they’re tiny — an adult is the size of a sesame seed — and their bites are painless, so a person may not see or feel them. They’re slow feeders and can suck blood for several days before dropping off. It takes about 24 hours for an infected tick to transmit Lyme disease. That’s why early detection and treatment is key. If attached for longer than 24 hours, a doctor can prescribe an antibiotic to prevent the disease, but it should be taken within 72 hours of removing the tick.

Early symptoms usually occur within 30 days of being bitten and include fever, chills, headache, stiff neck, fatigue, muscle and joint pains. A circular rash, known as a bull’s-eye rash, occurs in about 75 per cent of cases.

Patients and advocacy groups say the illness can go undetected, misdiagnosed and insufficiently treated. Because symptoms are non-specific it can be tough for doctors to diagnose without the characteristic rash. Some doctors delay treatment until they get a positive lab test or will outright dismiss Lyme disease as a possibility, and refer patients to mental health services for help in dealing with their issues.

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In part, that’s why the Ministry of Health and Long-Term Care appointed a Lyme Disease and Tick-borne Illnesses Task Force — comprising patients, advocates, health professionals and academic researchers — to make recommendations on how to improve supports. (This builds on other ministry efforts, such as the 2016 plan to improve awareness, education, prevention and control of Lyme disease, called Combating Lyme Disease Through Collaborative Action: Ontario’s 10-Step Education and Awareness Plan.)

Last month, the task force submitted its report to the ministry which is currently reviewing it. Key priorities for immediate action include establishing centres of excellence for tick-borne illnesses; reviewing current clinical practice guidelines and diagnostic testing methods; and improving communication to health professionals about standards for diagnosing and treating Lyme disease.

“We really did hear a lot of stories about patients having trouble navigating the system,” says the chair of the task force Adalsteinn Brown, a University of Toronto professor who’s the interim dean of the Dalla Lana School of Public Health. “There’s a need to provide support, both to patients and to (health care) providers.”

If you’re a Lyme disease patient who’s had difficulty navigating the health care system, contact iteotonio@thestar.ca

How to avoid tick bites:

Wear long pants and long sleeves.

Light-coloured clothing makes ticks easier to spot.

Apply insect repellent containing DEET or icaridin.

After being in wooded or bushy areas, shower to remove ticks before they become attached.

Do a full bodycheck for attached ticks — and check your children and pets.

If you find a tick on your body, remove it as soon as possible.

On your property:

Mow the lawn regularly.

Remove leaf litter, brush and weeds from the edge of the lawn.

Trim branches and shrubs to let in more sunlight.

Move swing sets and sandboxes away from the woodland’s edge and consider placing them on a wood chip or mulch foundation.

Keep rodents, deer and birds, which ticks feed on, away from the yard.