Emerging tickborne diseases in children: What we can learn from a new CPSP study

Dr. Kescha Kazmi

As summer approaches, children and adolescents will spend more time outdoors playing sports and enjoying nature. While this is essential for young people to maintain a healthy lifestyle, it’s important for families to be mindful of tick exposure while outdoors. Tickborne diseases are becoming a significant public health concern in many parts of Canada. Due to climate change, ticks are growing in abundance and expanding into regions where they were previously uncommon. As a result, an increasing number of Canadians are being exposed to ticks that may carry different pathogens. Children are at particular risk for tickborne diseases as they often spend more time outdoors, tick attachment can go unnoticed, and early symptoms may be mistaken for other childhood infections, delaying diagnosis and treatment.

While Lyme disease remains the most common tickborne disease in Canada, other lesser-known diseases may go under-recognized. The tick species responsible for transmitting Lyme Disease, Ixodes sp. or deer tick, also transmits other tickborne diseases including anaplasmosis, babesiosis, and Powassan virus disease.

Anaplasmosis is a bacterial infection that shares similar symptoms to Lyme disease except without a rash. It can also present with gastrointestinal symptoms such as diarrhea, abdominal pain, and vomiting. Reported cases of anaplasmosis have increased in recent years, making it one of the fastest‑growing tickborne infections in Canada. Babesiosis is a parasitic infection that causes fever and hemolytic anemia. Although still uncommon in Canada, cases have been reported in provinces where deer ticks are established. Powassan virus disease is rarer but can potentially cause severe encephalitis and meningitis. As of 2024, anaplasmosis, babesiosis, and Powassan virus disease are nationally reportable to the Public Health Agency of Canada.

Less common tickborne diseases that are not nationally notifiable include hard‑tick and soft‑tick relapsing fever, Rocky Mountain spotted fever (RMSF), and tick paralysis. Hard‑tick relapsing fever is caused by Borrelia miyamotoi and transmitted by deer ticks in eastern Canada, while soft‑tick relapsing fever is caused by Borrelia hermsii and is transmitted by soft-bodied ticks (Ornithodoros sp.) and found in southern British Columbia. These infections can cause recurrent fever episodes. RMSF is a rickettsial infection transmitted by Rocky Mountain wood ticks and dog ticks (Dermacentorsp.) and can cause fever, headache, and rash. Delayed treatment is associated with high morbidity and mortality. Although rare in Canada, a small number of cases are reported each year, primarily in western Canada. Notably, two human cases were reported in Ontario in 2025, representing the first locally acquired RMSF cases in Ontario in nearly 50 years (1). Lastly, tick paralysis is caused by a neurotoxin released in Rocky Mountain wood ticks and dog ticks’.saliva after prolonged attachment. It presents as an ascending paralysis and is treated by prompt identification and removal of the tick. Cases are seen most often in western Canada.

Despite the rising prevalence of tickborne diseases in Canada, there are important gaps in our understanding of where these diseases occur and how they present clinically in children. Many healthcare providers are unaware of these tickborne diseases and symptoms can be non-specific, which likely contribute to their underdiagnosis and recognition. While national surveillance exists for some tickborne diseases, limited clinical and epidemiologic data are captured through the national human case surveillance system and many tickborne diseases are not nationally notifiable.

As climate change increases the risk of exposure to tickborne diseases, enhancing awareness and surveillance efforts is crucial to controlling their spread in Canadian children. Through this CPSP study, we aim to better characterize the burden of non-Lyme tickborne diseases in children across Canada, identify geographic areas of risk, and describe clinical patterns of presentation, management, and outcomes. These findings may help inform diagnostic considerations and public health strategies for primary care providers and public health officials.

The CPSP study, Tick-born diseases (excluding Lyme disease) launched in May of this year and runs until 2029.

Reference:

1. Ontario Agency for Health Protection and Promotion (Public Health Ontario). Rocky Mountain spotted fever in Ontario. Toronto, ON: King's Printer for Ontario; 2025.

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