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First case in Quebec: a new tick-borne infection identified
Anne-Sophie Poiré
Monday, August 18, 2025 4:41 PM
A new tick-borne infection, more severe than Lyme disease, has been reported in Quebec. The first case of Rocky Mountain spotted fever, which is widespread across the American continent, was reported in the Eastern Townships at the beginning of the summer. Should we fear its arrival in the region?
"I thought it would happen in Quebec a little later, in five or ten years. But now it's happened, we've had our first case," says Alex Carignan, a microbiologist and infectious disease specialist and holder of the Research Chair on Lyme Disease and Emerging Infections at the University of Sherbrooke.
Rocky Mountain spotted fever is a well-known infection, he said, having been present for several years throughout the United States, Central America and parts of South America.
It is still emerging in Canada and Quebec, where a first case was identified at the beginning of the summer in Estrie.
Like most infected people, the patient responded well to doxycycline treatment, which is also used to treat Lyme disease.
The bacteria responsible for the fever, however, is transmitted by a different tick.
New tick, new bacteria
The Dermacentor tick – also known as the American dog tick – is responsible for the spread of Rocky Mountain spotted fever. The blacklegged tick carries Lyme disease.
This species has been on the radar of Bishop's University tick surveillance program since 2017.
"Generally speaking, infected patients recover without complications," assures Dr. Carignan .
"But spotted fever can be more severe," the specialist adds. "Several cases of death have been reported following this infection if it is not treated early enough. Deaths are extremely rare with Lyme disease, whereas with fever, we see them much more."
The infection causes high fever, headache, confusion, and a characteristic rash on the lower limbs that appears as small, dark, reddish lesions.
"It was these red rashes that led our teams to suspect Rocky Mountain spotted fever," explains Alex Carignan.
Climate change again
The microbiologist-infectious disease specialist nevertheless wants to be reassuring: "there is no reason to be alarmed."
"With climate change, we've been observing ticks migrating north for some time now," says Dr. Carignan .
The Dermacentor tick infected with Rocky Mountain spotted fever probably arrived in the Eastern Townships by land or by bird, he said.
"Rocky Mountain spotted fever is nevertheless part of a larger picture where we will see more tick-borne infections. It is essential to adopt protective behaviors," the specialist emphasizes.
The Ministry of Health recommends wearing long, light-colored clothing, tucking pants into socks and sweaters into pants, and using insect repellent when outdoors. It's also advisable to inspect your body and quickly remove ticks with fine-toothed tweezers.
https://www.tvanouvelles.ca/2025/08...nfection-transmise-par-les-tiques-repertoriee
