For ten years, the number of cases of Lyme disease recorded in Quebec has been increasing and, according to the first figures revealed by the Ministry of Health and Social Services (MSSS), this upward trend will continue in 2024.
The MSSS already reports 49 cases in the province for the period from 1er January to 1er June.
Once again, the vast majority of cases are concentrated in southern Quebec, most in Estrie (27 cases) and in the Montreal region (11).
Such a figure so early in spring suggests a very active “tick season”, according to Catherine Bouchard, veterinary epidemiologist at the Public Health Agency of Canada, who leads several research projects on Lyme disease and other diseases. transmitted by ticks, linked to climate change.
In 2022, the last full year covered by MSSS statistics, there were 527 cases of Lyme disease recorded in the province. The previous year, we reached a historic high of 650 cases. In 2014, there were only 66.
“Even if the number of infections varies annually, the underlying trend is increasing. This was unfortunately anticipated with the burden of climate change,” says the researcher, who has been following the phenomenon for almost 20 years.
Rising global temperatures mean that the blacklegged tick, the main vector of Lyme disease, is more abundant where it is established and is now found in regions that were once hostile to it, such as Saguenay. –Lac-Saint-Jean, which reports a case in 2024.
Shorter and less snowy winters favor an earlier awakening of the tick, since to be active and bite a human or animal, the mite must wait until temperatures reach 4°C and the snow cover disappears. The tick activity season is longer than in the past, and now extends into spring and fall.
“Our seasonal patterns change. The period of activity for ticks looking for their first seasonal meal in spring arrives more quickly, from March and April. And we humans too, arrive earlier in the season in the woods, forests and our gardens, where the ticks are found,” points out Catherine Bouchard.
Symptoms of Lyme disease range from a simple rash to fever and body aches. In the most serious cases, when the disease is not identified or treated in time, there is pain, dizziness, headaches and even facial paralysis.
The tip of the iceberg
Even though Lyme disease has been a notifiable disease (MADO) in Quebec since 2003, the number of infections is probably higher than government data indicates.
In many cases, people bitten by a tick will not even realize it.
“These are general symptoms, sometimes self-limiting, which can resolve without antibiotics,” emphasizes Catherine Bouchard, who is also an associate professor at the Faculty of Veterinary Medicine at the University of Montreal. How we react depends on our immune system. Not all people will suspect the disease and seek medical attention. »
Health personnel must also be able to recognize the symptoms of Lyme disease and other zoonoses transmitted by ticks, such as anaplasmosis, which is also increasing in Quebec.
So many reasons to be extra vigilant during a walk in the forest or a gardening session, in particular by wearing long clothes and using insect repellents.
“We have to take this seriously and examine ourselves in a military, systematic way, when we return from our outside activities,” advises Catherine Bouchard. It is by recognizing a tick on our body and removing it that we can avoid diseases. The sooner you safely remove a tick, the less likely you are to develop infections. »