Lyme Disease spreading in the Montérégie

Translated by Cathleen Johnston

Publié le 14 mars 2017

Lyme Disease is transmitted to humans through Deer Tick bites.

©TC Média Archives

Several towns in the Montérégie have been added to the 2016 list of municipalities whose residents are at risk of exposure to ticks carrying Lyme Disease. Others have had their risk level raised.

The number of cases is slowly increasing so that, from year to year, there will be more municipalities with at least three cases. Dr François Milord

This information is revealed on the 2016 provincial map published on February 24 by the National Institute of Public Health. Salaberry-de-Valleyfield as well as a number of municipalities in the Haut-Saint-Laurent are considered areas of "moderate risk" for contracting the disease.

Dr François Milord, medical advisor for the organization, mentioned that two factors can cause a change to a municipality's risk level.

The first is the discovery of well established tick colonies in the municipality. This is done through field work carried out in wooded areas where ticks, which can carry the disease, live.

The second factor is the number of people in the municipality who have contracted the disease. For this information, the Direction de la santé publique (DSP) contacts physicians who are obliged to report any cases of the disease.

The physician will indicate the probable area where his patient would have come in contact with an infected tick.

For a municipality to be considered at moderate risk, at least three cases have to have been reported.

According to Milord, it is difficult for a municipality to achieve a level below moderate risk, because prevention measures are aimed at informing the population but not at decreasing the incidence of ticks.

"If ticks are to be destroyed in a wooded area, significant interventions must be carried out on the natural environment, either by decreasing the animal population since ticks live on animals, or by using chemical products," he explained.


Lyme Disease, which originates in the United States, has reached Québec and is gradually spreading.

"The number of cases is slowly increasing so that, from year to year, there will be more municipalities with at least three cases," mentioned Dr Milord to explain the addition of new towns on the list.

He indicated, however, that it is difficult to predict if ticks carrying the disease will eventually be found throughout Québec. Since the Montérégie is one of the regions most at risk, the specialist fears that there is a good chance its wooded areas will be affected in the next few years.

How to protect yourself

Stay on pathways

Keep skin covered

Use mosquito repellent

Check your body after walking in the woods


Painless skin rash, more than 5 cm around the site of the bite



Joint pain