Increased infectious disease risks moving north as Canada’s temperatures rise

black-legged tick

“Climate Change: The Rising Threat of Tick-Borne Illnesses and Mosquito-Borne Diseases”

Fifteen years ago, young Ontario student Justin Wood’s life took a drastic turn when he fell ill, unable to participate in sports or academic activities. After years of suffering, he was diagnosed with Lyme disease, a rare tick-borne illness at the time. Fast forward to today, and the landscape of infectious diseases in Canada is rapidly evolving due to climate change. The warming climate is not only expanding the range of pathogens carried by ticks and mosquitoes but also increasing the incidence of diseases like Lyme disease and dengue fever.

The Growing Threat of Lyme Disease

Lyme disease, once a rare occurrence in Canada, has seen an exponential increase in cases over the past decade. With the expansion of black-legged tick populations, the number of ticks carrying the bacteria responsible for Lyme disease has also risen. This phenomenon has led to a growing concern for public health as more Canadians are at risk of contracting this debilitating illness.

In addition to Lyme disease, the threat of other tick-borne pathogens like Babesia odocoilei and Babesia microti is also on the rise. These parasites cause babesiosis, a disease with symptoms similar to the flu. As temperatures continue to rise, ticks are finding new habitats to thrive, increasing the likelihood of these diseases spreading further.

The Emerging Risk of Mosquito-Borne Diseases

While Canada was once shielded from mosquito-borne diseases like dengue fever and malaria, the changing climate is creating favorable conditions for exotic mosquito species to establish themselves in the country. The presence of Aedes albopictus and Aedes aegypti mosquitoes in Ontario is a worrying sign of the changing ecosystem.

As temperatures increase and extreme weather events become more common, the risk of food-borne diseases associated with warm weather is also on the rise. Studies have shown a strong association between rising temperatures and the prevalence of E. coli, salmonella, and vibrio infections, posing a significant threat to public health.


The impact of climate change on the spread of infectious diseases in Canada cannot be understated. As tick-borne illnesses like Lyme disease and mosquito-borne diseases like dengue fever become more prevalent, it is crucial for public health authorities to take proactive measures to mitigate these risks. By addressing the environmental factors contributing to the rise of these diseases, we can work towards a healthier and more resilient future for all Canadians.



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