According to data from the health monitoring department, as of June 22, 103 cases of Lyme disease have been declared in Quebec, half of which are in Estrie. This makes it by far the most affected region.
In 2023, of the 652 cases declared, 322 were identified as probably acquired in Estrie.
The proximity to the American border partly explains why Estrie is the epicenter of cases in Quebec. Dr. Geneviève Baron, public health and preventive medicine doctor at the CIUSSS de l’Estrie-CHUS, said that until around 2011, the region had no cases of Lyme disease, but some caught it during of trips to American states where ticks survived the winter.
“With the milder climate, ticks have slowly established themselves in our region,” explained Dr. Baron. There are areas that are perhaps more affected because ticks have been established there for longer, but which are also areas that are more suitable as habitat.”
Deer, for example, which are quite numerous in certain areas of Estrie, are animals on which ticks like to breed.
The number of municipalities considered in an endemic area has exploded, from 117 in 2023 to 461 this year. The INSPQ emphasizes, however, that this sharp increase is largely due to the surveillance criteria which have changed.
It is possible to consult the map on the INSPQ website which details all the municipalities where blacklegged ticks are present and active as well as the map of endemic areas for Lyme disease in Quebec.
Endemic area
To be considered an endemic area, a municipality must have at least three reported, locally acquired human cases in the previous five years or have 23 submissions of human-caused blacklegged ticks under passive surveillance in the last five years.
If all three stages of the tick (larva, nymph, adult) are spotted or at least six specimens of the same stage are collected in one year, the municipality is also classified as an endemic zone. A new criterion has been added, that of being 20 km or less from a municipality that meets one of the endemicity criteria.
“In 2024, the definition of the endemic zone for Lyme disease was expanded to better represent the epidemiological situation of this disease in Quebec,” explained the INSPQ in an email sent to The Canadian Press.
With the new definition, the Capitale-Nationale and Chaudière-Appalaches have been added to the map of endemic zones in Quebec.
Regions spared
The areas most at risk are those where populations of blacklegged ticks are established and infected with the bacteria that causes Lyme disease. According to the INSPQ, “the current distribution of populations of blacklegged ticks established and infected with the bacteria will continue to expand in Quebec.”
Dr. Baron believes that soon all of southern Quebec will be affected by Lyme disease.
“Quietly not quickly, with birds – because ticks can be carried by birds – with deer and other small mammals, it is slowly expanding towards the North,” she explained.
There is an absence of blacklegged ticks in the more northern regions: Côte-Nord, Northern Quebec, Terres-Cries-de-la-Baie-James and Nunavik. However, the INSPQ mentions that the risk of acquiring Lyme disease is possible in all regions of Quebec due to the possible presence of ticks which are infected and brought occasionally by migratory birds.
Northern Quebec still remains protected by its climate. Ticks survive in relatively humid habitats such as forests and woodlands. “Tundras are not suitable habitats for ticks, so unless with climate change the vegetation changes, they should not be habitats that host many ticks,” said Dr. Baron.
Advice to the public
The first symptoms of Lyme disease, which can appear in the month following a tick bite, are a redness which increases over time, generally exceeding 5 cm, fever and muscle or joint pain.
When the disease is left untreated, arthritis, facial paralysis, heart rhythm disturbances and other multiple skin rashes may develop.
Lyme disease is treated with antibiotics and there are treatments for all stages of the disease, Dr. Baron said.
In the event of an injection, it is recommended to call 811. The healthcare professional on the line will assess the condition of the injection with the patient and the patient may be redirected to a pharmacist for preventive treatment if they are eligible.
The proximity to the American border partly explains why Estrie is the epicenter of cases in Quebec. (University of Ottawa/Roman McKay)
If the person already has symptoms when they notice a tick bite, they should consult a doctor.
To avoid tick bites, Dr. Baron advises applying mosquito repellent containing DEET, wearing long clothing when going out in nature and avoiding walking in vegetation.
When you return home, showering will remove any ticks that are not yet attached and inspecting your body will help spot intruders. If you see a tick, gently pull upwards with eyelash tweezers. For those who have pets that go outdoors, it is prudent to examine them regularly and remove ticks in the same way.
Many people are bitten by a tick without even leaving their yard. To avoid becoming a breeding ground for ticks, you should get rid of piles of dead leaves — a place that ticks love — and mow your lawn. As these insects hate drought, it is good to have a patio or children’s play area in a place exposed to the sun.
