Lyme disease | Ticks attacking Quebec

The blacklegged tick, through which Lyme disease is transmitted to humans, risks establishing itself in most of the inhabited territory of Quebec, show new projections from the National Institute of Public Health of Quebec (INSPQ) . Close-up in five questions that bother us.

If the Quebec climate of 2080 evolves according to a high scenario*, the blacklegged tick (Ixodes scapularis) will be present all year round in almost all of Gaspésie, on all of Anticosti Island and as far as the Cree village of Waskaganish near James Bay, shows the map published this week by the INSPQ. A much larger territory than at present¹.

* Increase of 4 to 8°C in the North and 4 to 6°C in the South compared to the period 1991-2020²

Why produce such a map?

“What’s super interesting about mapping the tick’s area Ixodes scapularisis that it allows us to have an early signal of the location where all the diseases that it can transmit could possibly be found,” explains Danaelle Page, scientific advisor to the Infectious Diseases in Community team at the INSPQ. .

The maps illustrate areas of favorable temperature, but “for a tick to establish itself in an environment, other factors are also needed,” recalls M.^me Page by mentioning the animal hosts which are rodents and deer. “In the absence of that, even if the temperature is favorable, that does not mean that there will be establishment. »

Isn’t this scenario exaggerated?

“There is not a single entomology researcher who took the plunge when they saw these cards,” says Jade Savage, professor at Bishop’s University and principal investigator of eTick, whose data was used by the INSPQ, in combination with those of Ouranos.

“One of the reasons why we really need to closely monitor tick populations is that their distribution changes very quickly,” says M.^me Savage, herself an entomologist. Arriving in Quebec “not even 30 years ago”, the blacklegged tick has expanded its territory “spectacularly” and “there is no reason to believe that it will not follow the changes climate change as soon as it is able to do so.

Will we be overwhelmed by Lyme disease?

The map “is really not an indicator of where there is Lyme disease at the moment, but of where we need to prepare ourselves that eventually we might have (cases of) Lyme disease.” Lyme and probably other pathogens,” says M.^me Page.

The current risk map is much sparser¹. And according to 2023 surveillance data for all of Quebec, only one in three ticks carry the bacteria responsible for Lyme disease. “We must not panic, but we must still be aware that ticks are present and that they are there for good, so we must adapt our lifestyle habits. »

So how to adapt?

“It’s to avoid getting bitten in the first place. It’s a good thing to check, after a walk (or going) in your garden, to make sure you don’t have any ticks and to check your children. If we remove it early, there is much less risk of having problems,” underlines Christophe Augé, pharmacist in Ascot Corner, in Estrie, who has trained many colleagues in post-exposure prophylaxis to a tick bite ( PPE)². Pharmacists can prescribe this antibiotic PEP by exercising their professional judgment, which takes into account in particular the area where the person was bitten. “We know very well that it will expand due to climate change. It’s clear that we haven’t finished talking about it. »

The nymphs, much smaller than adults, can go unnoticed, says entomologist Jade Savage. “So it is important to remain vigilant all year round, as soon as temperatures are above 4°C. »

What more ?

“For now, we are focusing on the tick Ixodes scapulariswhich transmits Lyme disease, anaplasmosis and, more rarely, babesiosis and others,” indicates the D^r Alex Carignan, holder of the Research Chair in Lyme disease and emerging infections, which will start in July at the University of Sherbrooke³. But “we want to quickly expand to all species of ticks known to be pathogenic”, including the star tick (Amblyomma americanum), present in the American southeast, which we “expect to see arrive within a few years”. The Chair wants to train researchers and health professionals and collect clinical samples from Quebecers bitten by a tick. The eTick platform, where individuals can send a photo of a tick to have it identified, will help recruit participants from Estrie and Montérégie⁴. Work on the effectiveness of PEP, diagnostic tests and vaccines currently in development is also planned.

1. Consult the map of the current risk of acquiring Lyme disease in Quebec

2. Read about Lyme disease prevention measures

3. Visit the website of the Research Chair in Lyme Disease and Emerging Infections

4. Visit the eTick website

See the current distribution of blacklegged ticks in Quebec

Consult the projection of temperature increases by 2100