A lesser known tick-borne disease called anaplasmosis is on the rise in southeastern Ontario.
In May, Public Health Ontario released a report that revealed that there were 40 confirmed and probable cases of anaplasmosis reported in the province in 2023; over three-quarters are from the Ottawa, Kingston, and Leeds-Grenville areas.
While there have been no reports of anaplasmosis this year, new cases will almost certainly emerge as the summer wears on.
Anaplasmosis is an infection spread by black-legged ticks, the same species that can transmit Lyme, babesiosis, and Powassan virus diseases. It is characterized by flu-like symptoms, such as fever, fatigue, muscle aches, and headache. In contrast, Lyme disease is not known to cause vomiting or diarrhea, and typically causes a rash that looks like a target mark with a red ring circling around the bite. Anaplasmosis can usually be treated with antibiotics, but have been known to be deadly to immunocompromised individuals.
Last July, the ministry designated anaplasmosis, babesiosis, and Powassan virus as three new tick-borne diseases of public health significance. Lyme disease has been on the list since 1998.
Roman McKay, the project manager of UPTick—a research project focused on the intersection of ticks and urban living around Ottawa—says that trends point to cases of tick-borne diseases continuing to rise. This could be even more prominent in southeastern Ontario.
“Ticks have been expanding their geographic ranges in recent decades, largely due to climate change,” says McKay. “This is likely to continue as climate change progresses, leading to weather conditions that are favourable for black-legged ticks.”
Black-legged ticks are mainly found around deciduous or mixed forest environments where suitable hosts, such as white-tailed deer, are available to feed on. This was previously limited to southern Ontario, but as the climate warms, ticks are moving further north.
In 2023, Ottawa Public Health reported 14 confirmed or probable cases of anaplasmosis. Half reported tick exposure in Ottawa, and the other half were found in surrounding areas, such as Perth.
Emily Morrison, a program manager with Ottawa’s public health unit, says that Ontarians should be aware of the presence of ticks when they’re outside this summer.
“There are many health benefits from being active and enjoying the outdoors in the warmer weather,” she said in a written statement. “If you will be in outdoor areas suitable for black-legged ticks, such as wooded areas or areas with tall grasses, it is important to be aware of the risk of ticks and tick-related diseases, and how to protect oneself.”
Public Health Ontario is expected to release an updated report with more data for 2024 later this month.
How to avoid tick bites
It might be impossible to fully avoid ticks this summer, but there are steps you can take to avoid getting sick.
“Ticks that are removed within 24 hours likely won’t get a chance to transmit disease-causing bacteria,” says McKay.
Here are some tips from Public Health Ontario to protect yourself from these pesky insects:
- Wear light-coloured clothing, so it’s easier to spot ticks
- Wear long-sleeved shirts, long pants tucked into socks, and closed-toed shoes
- Use an insect repellent with DEET or icaridin in it
- After being outdoors, check for ticks on your body, especially in nooks and crannies, such as behind your knees or under your arms
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