Lyme disease is continually progressing in Quebec with an increase in the number of cases and new municipalities in the endemic zone each year, confirms the Institut national de santé publique du Québec (INSPQ).

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.

“As the climate warms, 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.

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.

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 broadened to better represent the epidemiological situation of this disease in Quebec,” explained the INSPQ in an email sent to La Presse Canadienne.

With the new definition, the Capitale-Nationale and Chaudière-Appalaches have been added to the map of endemic zones in Quebec.

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 spreading north,” she explained.

Northern Quebec still remains protected by its climate. Ticks survive in relatively humid habitats like 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.

The first symptoms of Lyme disease, which can appear in the month following a tick bite, are a red rash that 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 can develop.

Lyme disease is treated with antibiotics and there are treatments for all stages of the disease, Dr. Baron said.

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 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 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.