Tick-Borne Disease Spreading in Canada
Babesiosis is a rare and life-threatening disease similar to malaria that is becoming more common in Canada.
The disease is transmitted through blacklegged ticks, also known as deer ticks, which are found in some provinces and parts of the northeastern United States. Babesiosis can be fatal, particularly for elderly and immunosuppressed individuals, causing complications such as renal, liver and heart failure, and respiratory distress syndrome. In March 2023, the U.S. Centers for Disease Control and Prevention reported an increase in babesiosis cases in northeastern states, with the disease now endemic in Maine, New Hampshire, and Vermont.
Ticks can be active at temperatures above 4°C, meaning that they can be active year-round in Canada. The peak tick season in Canada is from mid-spring to early fall, and climate change is contributing to the increased prevalence of tick-borne diseases. Ticks are thriving in more suitable environments, with shorter winters improving their reproduction and extending their seasonal activity.
Until recently, babesiosis was not found in Canada, but migratory birds and the changing climate have facilitated the northward spread of blacklegged ticks. They are now present in increasing numbers in Manitoba, Ontario, Quebec, Nova Scotia, and New Brunswick, bringing babesiosis with them. The disease is transmitted to humans during the tick’s nymphal stage through its saliva when it bites into the skin. Babesiosis can be transmitted by ticks at various stages of their development, but it is not as common.
Babesiosis is caused by a parasite that infects red blood cells and is transmitted primarily through the bite of blacklegged ticks. Although babesiosis is similar to Lyme disease, it doesn’t cause a rash. Lyme disease is the most common tick disease in Canada and is also transmitted by deer ticks. It is caused by a bacteria called Borrelia burgdorferi and is characterized by a “bullseye” rash. In 2021, there were 3,147 reported cases of Lyme Disease across Canada.
Babesiosis is still rare in Canada, although it is on the rise. The species Babesia microti and Babesia duncani are becoming more common, but there is another species called Babesia odocoilei that is more concerning. A 2021 study found that Babesia odocoilei was prevalent in blacklegged ticks in certain parts of Ontario. The mortality rates for those infected with babesiosis are around five per cent, but can be as high as 21 per cent among hospitalized and immunocompromised individuals.