When Sally Bowen first left Toronto for a man she loved and a sheep farm in rural Ontario, she knew she was signing up for a lifetime of rewarding hard work. She expected there would be some hardships and had anticipated sleepless weeks spent keeping orphaned lambs alive, and backbreaking days weeding under a sweltering August sun.
Nothing could prepare her, however, for the lingering effects of what an American specialist eventually diagnosed as Lyme disease or some other tick-borne illness. Bowen’s case is so severe, that for decades, she has been chronically tired and unable to eat without a feeding tube.
“It was 1996 and, at the time, we had about 1,100 breeding ewes,” Bowen said, recounting how that spring she was responsible for the exhausting job of bottle-feeding roughly 160 orphan lambs. “Towards the end of the foster lambing, I got incredibly ill. I'm not usually a sickie ... but I collapsed and (had) flu-like symptoms for almost a month.”
It was soon clear that, in addition to common Lyme symptoms like exhaustion and aching joints, her stomach muscles had stopped working properly, making eating impossible. While the severity of Bowen's symptoms are rare, experts warn that cases like hers could become more common as climate change puts farmers, foresters, and others who work the land at greater risk of Lyme disease and other tick-borne illnesses.
Adult ticks are sesame seed-sized insects (young ticks are smaller) that drink blood from birds and mammals to survive, and prefer brushy, wooded habitats. While several species exist, deer ticks and western blacklegged ticks are carriers of the bacteria that causes Lyme, Borrelia burgdorferi, and can transmit it to people in their bite.
“What's happening is that ticks are expanding north, and their populations are growing very quickly,” said Robert Colautti, a professor of ecology and genomics at Queen's University.
Once found mainly in a small corner of southern Ontario, the insects now thrive across the Maritimes, in southern Québec and Ontario, and in Manitoba. Western blacklegged ticks are common in southern B.C., including the Lower Mainland and southern Vancouver Island.
Their rapid spread is largely due to warmer and longer springs, summers, and autumns. Warm days allow the insects to reproduce more quickly and rapidly boost their population, explained Nicholas Ogden, senior research scientist at the Public Health Agency of Canada. Migratory birds arriving in Canada from the U.S. also act like a “conveyor belt,” bringing the bugs north from areas where they have long been common.
Climate change is warming Canada about twice as fast as the global average, and the provinces with Lyme-bearing ticks have seen their average annual temperatures increase by roughly 1.3 C, according to a 2019 report by Environment and Climate Change Canada.
“It seems that the warming has allowed more of Canada to become a zone in which ticks can complete their life cycle,” Ogden said. Moreover, forest cover has increased in tick-prone areas since the 1950s as the number of farms has decreased and agricultural land has gone fallow, bolstering tick habitat.
"Ticks ... carry a variety of microbes in their saliva and in their guts. There's a whole bunch of diseases that are tracked not as intensely as Lyme disease," says @QueensU professor Robert Colautti.
Added to this population explosion is the prevalence of the bacteria that causes Lyme disease, which accumulates in rodents and birds before infecting ticks and humans. For instance, in some parts of the U.S., roughly 70 per cent of ticks carry the microbe, significantly increasing the risk of exposure to people, he explained.
In Canada, the number of people diagnosed with Lyme has skyrocketed in recent years. In 2009, about 140 people were confirmed with the illness. By 2019, 2,630 people had the disease, Health Canada reported.
However, Colautti and Ogden emphasized Lyme disease isn't the only reason Canadians should avoid tick bites since the insects can also carry several harmful and lesser-known pathogens.
“Ticks ... carry a variety of microbes in their saliva and in their guts. There's a whole bunch of diseases that are tracked not as intensely as Lyme disease,” explained Colautti.
Those include illnesses like Rocky Mountain spotted fever — a bacterial infection that can severely harm internal organs — and the Powassan virus, which attacks the nervous system. Colautti is leading an international project, partnered with the Mitac Globalink research initiative, to develop a rapid, field-based testing system that will make it easier for doctors and public health officials to catch and treat tick-borne illnesses early.
It's possible one of these other diseases could have caused Bowen's life-altering symptoms, the farmer said. She will never know for sure: The bacteria or virus that caused her symptoms was long gone years before doctors identified a tick bite as the likely cause of her illness. At the time, she added, few Canadian doctors even considered the possibility that Lyme disease or another tick-borne illness could be causing her symptoms.
Still, Ogden said that farmers, foresters, and others who spend time in the bush shouldn't avoid the outdoors. With adequate precautions, like bug repellant and regular checks for ticks, being outside and active is far healthier than sitting indoors out of fear.
“People should be aware, but not necessarily terrified of getting out in the woods. Getting out in the countryside is an inherently healthy thing to do,” he said. “It's important to recognize the risk and be aware of how to minimize getting bitten by ticks.”