Canada: Emerging tick-borne pathogens on the rise in the central part of the country


Tick-borne pathogens, known to cause diseases such as Lyme disease, are on the rise in central Canada – presenting new risks in areas where they had not been detected before.

The findings are by researchers at McGill University and the University of Ottawa Demonstrate the need for more comprehensive testing and tracing to detect the spread and potential risk of tick-borne pathogens to humans and wildlife across Canada.


Most people know that diseases can be transmitted to humans through the bite of an infected tick. Kirsten Crandall, a doctoral student under the joint supervision of McGill University Professor Virginie Mellen and Professor Jeremy Kerr at the University of Ottawa, explains that ticks can carry and spread many disease agents, called pathogens, that can make people and animals sick.

“While the bacteria that cause Lyme disease is the most common tick-borne pathogen in Canada, other tick-borne pathogens are also transmitted,” she adds.

To investigate the presence and spread of several emerging tick-borne pathogens, Crandall and her team analyzed small mammals and ticks collected in Ontario and Quebec. The researchers found that five emerging pathogens were present in their study sites in central Canada, including pathogens that cause Lyme disease and babesiosis, a parasitic disease similar to malaria.

They discovered that two pathogens, Babesia odocoilei And the Rickettsia rickettsi, outside their historical geographic range in Quebec. These pathogens spread both Babesia and Rocky Mountain spotted fever. “The presence of these pathogens alters the disease risk for Canadians and animals in some of the densely populated areas of Canada,” says Crandall.

Transmission spreads in different ways

Typically, pathogens are transmitted to ticks after they feed on the blood of an infected host, such as a small mammal. However, the researchers found evidence of pathogens that could be spread in other ways. Babesia odocoilei And the Rickettsia rickettsi It can also be transmitted directly from adult female ticks to tick larvae. In addition, small mammals such as mice can transmit the parasite hepatozone After eating an infected insect, spider, or tick.

“It is difficult to assess the prevalence of some emerging or re-emerging tick-borne pathogens, as many are not reported to public health agencies in Canada,” says Crandall. Only two tick-borne pathogens are listed as nationally notifiable diseases in Canada: Lyme disease (Borrelia burgdorferi) and tularemia (Francisella tularensis). However, we are seeing increasing cases of diseases such as anaplasmosis and babesiosis in humans in Canada.”

Detect spread and potential risks

According to the researchers, the prevalence of emerging tick-borne pathogens has increased steadily in Canada due to climate change, habitat fragmentation, and changes in the abundance of tick populations and their hosts.

“If we don’t know pathogens are out there, we can’t provide Canadians with the information they need to protect themselves. COVID has diverted public health resources away from challenges like this, and we need to remember that these tick-borne diseases are on the move as well,” Jeremy adds. Kerr, professor and research chair in the Department of Biology at the University of Ottawa.

“It’s a massive effort to track the emergence of these pathogens in real time across Canada, and this is when field research like ours can contribute the most. Our student’s work is a nice reminder that basic research matters and, in this case, can play a role.” have a role in public health,” says Virginie Mellen, associate professor at the Redpath Museum at McGill University.

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