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Instances of Lyme disease are increasing across Quebec every year, according to INSPQ, l’Institut national de santé publique du Québec.
INSPQ says that as of June 22, 103 cases of Lyme disease have been declared this season in Quebec, half of which are in Estrie. Of the 652 cases declared in 2023, 322 were identified as probably originating in Estrie.
The proximity to the U.S. border partly explains why Estrie is the epicentre of cases in Quebec. Until around 2011, the region had no cases of Lyme disease, but some people caught it during of trips to U.S., where ticks survived the winter, said Dr. Geneviève Baron, public health and preventive medicine doctor at the CIUSSS de l’Estrie-CHUS.
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“With the milder climate, ticks have slowly established themselves in our region,” Baron said. “Some areas are more affected because ticks have been established there for longer. Those areas are more suitable habitats for ticks.”
Ticks breed on deer, which are numerous in some parts of Estrie.
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 changes in surveillance criteria.
Maps on the INSPQ website show municipalities where blacklegged ticks are active as well as endemic areas for Lyme disease in Quebec.
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 classified as an endemic zone. A new criterion has been added: being 20 km or less from a municipality that meets one of the endemicity criteria.
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“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
According to the INSPQ, “the current distribution of populations of blacklegged ticks established and infected with the bacteria will continue to expand in Quebec.”
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, INSPQ says the risk of acquiring Lyme disease is possible in all regions of Quebec because of the possibility that ticks hitch a ride with migratory birds.
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Northern Quebec is protected by its climate. Ticks survive in relatively humid habitats, such as forests and woodlands.
“Tundras are not suitable habitats for ticks, so unless the vegetation changes with climate change, they should not be habitats that host many ticks,” Baron said.
Advice to the public
The first symptoms of Lyme disease, which can appear in the month following a tick bite, are a redness that increases over time, generally exceeding 5 centimetres, fever and muscle or joint pain.
When the disease is left untreated, arthritis, facial paralysis, heart rhythm disturbances and other skin rashes may develop.
Lyme disease is treated with antibiotics and there are treatments for all stages of the disease, Baron said.
In the event of a tick bite, it is recommended to call 811, where a health-care professional can assess the situation. The patient might be referred to a pharmacist for preventive treatment.
If the person already has symptoms when they notice a tick bite, they should consult a doctor.
To avoid tick bites, 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 a good idea to check 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 the 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.
Presse Canadienne’s health content receives funding through a partnership with the Canadian Medical Association. The Presse Canadienne is solely responsible for editorial choices.
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