Bull’s-eye rash, swollen knee joints among common symptoms
“We are not at all in the context of a crisis,” added Habel, a medical resident focusing on the prevention and control of infectious diseases. “We encourage people to take advantage of the weather to go outside.”
Lyme disease, which got its name after it was first diagnosed in Old Lyme, Conn., in the mid-1970s, is caused by the bacterium Borrelia burgdorferi when transmitted by the bite of a tick. Only the deer tick, or black-legged tick, transmits the disease in Quebec, and most cases have been concentrated in the Eastern Townships and Montérégie.
The most common symptoms are swollen knee joints and a telltale bull’s-eye rash, although some infected people do not have the rash. Other symptoms can include fever, chills, headache, fatigue, muscle and joint aches as well as swollen lymph nodes — symptoms that are so nonspecific that it can sometimes be difficult to diagnose Lyme disease initially.
The disease can be treated with a course of antibiotics over two to three weeks to clear the infection. In 10 to 20 per cent of cases, however, treated patients may suffer from lingering symptoms of fatigue, musculoskeletal pains, disrupted sleep, and lack of customary mental functions, observes the New England Journal of Medicine.
The number of confirmed cases of Lyme disease in Canada has climbed from 144 in 2009 to 992 in 2016, the federal government reports. Although the total in 2016 was high, it’s far below the estimates of 10,000 to 15,000 cases a year that have been predicted by some experts.
Nova Scotia reports the highest incidence of cases of any province, followed by Ontario and Quebec. The three provinces are responsible for 88 per cent of all cases in the country. “Surveillance in these three provinces indicates that populations of black-legged ticks have been established for years,” a government statement says.
On the island of Montreal, the number of cases increased to 46 last year from 25 in 2016. Prior to 2016, the annual number of cases was stuck at around 25 since 2013.
“In our interviews, when we speak with people, we’ve observed that they travelled to regions like the Eastern Townships and the Montérégie, Ontario and the United States,” Habel said. “These are residents of Montreal who go on vacation and who were bitten by a tick outside Montreal.”
Dr. Christopher Labos, a contributor to the Office for Science and Society at McGill University, said Lyme disease is on the increase for two reasons: much greater awareness of the infection as well as climate change.
“I think it’s a combination of the two,” Labos explained. “I think people are more vigilant about it now, but part of it is that because of global warming and milder winters, you’re getting more ticks. The ticks are able to survive through the winter.”
Climate change is also responsible for other tick-borne illnesses like West Nile virus spreading to Canada.
However, the number of cases of people infected with the virus has declined from a peak of 428 cases in 2012.
Given the numbers of cases of Lyme disease, Labos offers a nuanced message:
“For the person who gets sick, it’s very significant because they feel terrible and they feel debilitated. But it you look at the total number of patients, it’s a very small number compared to the whole population. So the risk of getting Lyme disease is still pretty low.”