Ticks are gaining ground in Quebec. Lyme disease too.
What there is to know
- For the year 2022, 586 cases of Lyme disease were declared, a decrease of 123 cases compared to the year 2021.
- In high-risk areas, the probability of contracting the disease from a bite varies between 1% and 3%.
- If the tick is removed within 24 hours, the risk of contracting Lyme disease is very low.
- In some regions where the risk is higher, it is possible to obtain a dose of antibiotic to prevent infection before the appearance of symptoms in the event of a bite.
When you take a quick look at the most recent data from the Institut national de santé publique du Québec (INSPQ), published this week, you might think that Lyme disease is on the decline: 586 cases were reported in 2022, a decrease of 123 cases compared to 2021.
But we must not stop at these statistics.
The disease continues to progress, says Najwa Ouhoummane, scientific advisor and epidemiologist at INSPQ and author of the report. Specifically, the long-term data indicates an upward trend.
“Ticks are here to stay,” explains Najwa Ouhoummane.
The record number of Lyme disease cases reported in 2021 can be attributed to the particular context of the pandemic and containment. “We observed a very strong enthusiasm for outdoor activities, since people could not necessarily travel outside the country,” notes Najwa Ouhoummane.
More people outdoors, so more exposure to ticks and Lyme disease.
With 320 cases, Estrie remains the most affected region, confirm the data for 2022. Montérégie comes second, with 113 cases.
The disease also continues to spread across the country. The risk level of 13 municipalities went from “possible” to “present” (two cases in the last five years) between 2022 and 2023. These municipalities are located in the following health regions: Capitale-Nationale, Mauricie-et- Centre-du-Québec, Estrie, Outaouais, Chaudière-Appalaches and Montérégie.
Fourteen municipalities moved to a “significant” risk level (at least three cases in the last five years) in 2023; they are located in Mauricie-et-Centre-du-Québec, Estrie, Outaouais and Montérégie.
“In high-risk areas, the probability of contracting Lyme disease following a bite varies between 1% and 3%,” says Najwa Ouhoummane.
Ticks, great travelers
This geographic expansion is not entirely the result of chance. “Ticks travel on the backs of birds and deer,” explains Catherine Bouchard, associate professor at the Faculty of Veterinary Medicine at the University of Montreal.
Once the deer or bird arrives in a new environment, the accompanying ticks will fall to the ground. If the climatic conditions and the characteristics of the new environment are favorable to their survival, they will establish themselves and reproduce. “This explains why certain regions present a greater risk than others,” explains Catherine Bouchard.
But not all ticks carry Lyme disease. The bacterium responsible for the disease originally circulated in the blood of rodents, mainly the white-footed mouse. It is also present in red squirrels and eastern chipmunks.
The tick therefore becomes a vector of the disease after biting an infected rodent. “Contrary to popular belief, the source of the pathogen is therefore the rodent, and not the tick,” says Catherine Bouchard.
Lyme disease is not the only disease that can be transmitted by ticks in Quebec. The others, although rarer, are anaplasmosis, babesiosis and Powassan encephalitis.
Better to prevent
It is therefore essential to protect yourself adequately when practicing activities in the forest. The winning formula is well known: avoid walking off the trails, wear long clothes, apply insect repellent solutions to the parts of the skin that are exposed.
But prevention can go further, explains Catherine Bouchard, of the University of Montreal. Once back home, a thorough visual inspection is paramount. It is also recommended to put your clothes in the dryer for at least 10 minutes and to take a bath or a shower to dislodge any tick that has not yet attached itself.
The tick escaped your vigilance and bit you? Do not panic.
If the tick is removed within a 24-hour window, the risk of contracting Lyme disease is very low.
Catherine Bouchard, veterinary epidemiologist at the University of Montreal
When removing the tick, make sure that its rostrum, the harpoon-shaped organ it uses to bite and penetrates the skin, is completely removed.
In some areas where the risk of acquiring Lyme disease is higher, it is possible to obtain a dose of antibiotic to prevent infection before symptoms appear in the event of a bite. This post-exposure prophylaxis should be taken 36 to 72 hours after the bite.
Since 2003, it has been mandatory for clinicians and laboratories to report cases of Lyme disease to public authorities. “The disease is well known and well taken care of by public health”, notes Najwa Ouhoummane.