Public health officials brace for uptick in Lyme disease
Risk zone now covers nearly all of city as insects migrate north
Deep inside Rouge Park, Durham Region health official Toni Moran sweeps a white flannel cloth slowly over thick brush to try and capture blacklegged ticks, whose numbers are growing and spreading across the country.
This is part of the battle against Lyme disease, a potentially debilitating condition affecting cardiac and nervous systems that is transmitted through the bite of an infected tick. Dragging helps determine if a tick population exists, how it’s evolving and the risk for exposure.
Ten minutes in, Moran captures her first tick, also known as a deer tick. To the untrained eye, it’s barely visible: adults are the size of a sesame seed.
“We hesitate to pinpoint areas where they may be . . . That would give the public a false sense of security if they’re in areas where we haven’t found them,” says the senior public health inspector with the Vector-Borne Disease Program. “If you’re outside in wooded or brushy areas in southern Ontario, you need to take precautions.”
In the GTA, part of York and Durham and nearly all of Toronto are in a risk area for Lyme disease, according to a 2017 map by Public Health Ontario, which defines a risk area as a 20-kilometre radius around where ticks have been found.
Last year, just half of Toronto was in a risk area, but this year the risk area blankets nearly the entire city.
In Canada, there were 841 human cases of Lyme disease in 2016, compared with 144 in 2009, when it became a nationally notifiable disease. In Ontario, there was a similar rise in cases, from 44 in 2005 to 343 in 2016.
But the real number affected may be tenfold, say experts.
“Lyme disease isn’t going to go away,” says Dr. Doug Sider, medical director of communicable disease prevention and control at Public Health Ontario, noting that the risk area will only increase. “But we are not powerless.” ‘Once ticks are established, they don’t leave’ As a result of climate change, ticks have moved north to Canada, hitching a ride on migratory birds, deer and small mammals as they feed, health officials say.
They thrive in wooded areas with deciduous trees, leaf litter and tall grasses. Because they’re prone to drying out, they’re unlikely to be on golf courses and sports fields with short grass, says Curtis Russell, a senior program specialist at Public Health Ontario.
Lyme disease is caused by the bacterium Borrelia burgdorferi. An infected tick must feed for at least 24 hours for transmission to occur. Ticks secrete an analgesic so you don’t feel pain when they bite.
“That’s where the risk is: people don’t notice them,” Russell says. “Ticks will bite you anywhere, but they typically bite around your hairline, armpits, the back of your knees, buttocks and groin area — areas that are harder to check.”
Not all ticks carry the bacteria. The prevalence of infection is higher in areas where they’re more established — such as Long Point Provincial Park, which was the only known risk area for Lyme in Ontario in the early 1990s — than where they’ve more recently appeared, such as Rouge Park.
“Once ticks are established, they don’t leave,” Russell says. And if they are introduced into a location without Lyme disease, there’s a three- to five-year lag before it shows up in the area’s mammals.
In Ontario, all public health units do passive surveillance, whereby people submit ticks, which helps pinpoint areas of concern. A growing number of units are also doing active surveillance, or tick dragging. Collected specimens are sent to public health for identification and to the National Microbiology Laboratory for bacteria testing. This year in particular, both labs have been inun- dated with submissions.
Toronto started tick dragging in 2013, focusing on one park. In 2016, it dragged in 36 parks and found ticks in six, including Algonquin Island Park, Highland Creek and Morningside Park. What residents can do In Rouge Park, Moran captures two ticks in an hour. She recommends people walk or cycle in the middle of trails, away from the brush, and routinely check themselves, their families and pets for ticks.
Also, wear light colours and long sleeves and tuck in clothing, including socks over pants, so ticks have farther to crawl, she says.
“Enjoy the outdoors,” Moran says. “Just take some basic precautions.”
Bug sprays with DEET offer protection. Permethrin-treated clothing can also be effective and continues offering protection for several washes. Such garments are not for sale in Canada to the general public, but Health Canada is reviewing an application that could make them available.
Once home, be sure to shower within one or two hours because ticks may not have had time to attach. Also, put clothing in the dryer for an hour so the high heat kills any ticks. If a tick is attached, use fine-tipped tweezers, grasp it close to the skin, and pull straight out — ensure the mouth is intact. If you’re worried about improper removal, see a doctor. What the experts can do Doctors are being told to consider prompt treatment if there’s been a known tick exposure, particularly in a risk area, and the patient has the classic symptoms, says Sider of Public Health Ontario, a provincial agency that provides scientific and technical advice on public health matters. Similarly, patients should see their physician if they suspect a tick bite and seek immediate treatment.
He says the true impact of the disease is unknown because it’s underreported, suggesting some doctors diagnose and treat early Lyme without notifying health units, while some may misdiagnose it because the symptoms are non-specific and often flu-like, including fever, chills and fatigue. A telltale sign is an expanding rash at the site of a tick bite, sometimes resembling a bull’s eye, but this doesn’t always occur. Symptoms typically appear within a week, but can surface between three and 30 days.
Antibiotics should clear early symptoms. But if untreated, Lyme can progress to a more serious illness causing problems such as joint pain, neurological issues, irregular heartbeat and difficulty concentrating.
For years, public health has been raising awareness on how to prevent, suspect, diagnose and treat Lyme. Ten years ago, it focused on getting its message to doctors. But in recent years it’s also worked with tourism groups, outdoor workers, outdoor activity groups and parks and recreation departments.
Given “the steady, inexorable climb” in Lyme cases, Sider says, “we need to double down” on those efforts.
In late May, the federal government said it plans to spend up to $4 million to establish a Lyme disease research network to improve diagnosis and treatment. It also released a federal framework to prevent and control Lyme disease over the next five years.
Last week, the University of Guelph announced a $1.4-million grant from G. Magnotta Foundation, named after Magnotta Winery co-founder Gabe Magnotta, who died in 2009 after a seven-year battle with Lyme. The money will go toward creating a research lab to improve diagnostic testing and treatment to prevent long-term suffering.