Ontario and Wisconsin report heightened Lyme disease risk as tick activity surges

Public health officials in Renfrew County, Ontario, recorded a record 79 cases of Lyme disease in 2025, the highest annual total ever reported. The Renfrew County and District Health Unit says blacklegged (deer) ticks are expanding northwest along the Ottawa River, with established risk areas from Arnprior to Chalk River and surrounding communities. Health officials attribute the spread to warmer weather and broader climate trends across eastern Canada and urge residents to use repellents, wear protective clothing, conduct tick checks, and seek medical attention for symptoms such as rash, fever, or joint pain.

In Wisconsin, the Department of Health Services warned that tick activity has reached its seasonal peak, driven by nymphal deer ticks that are especially hard to detect. Surveillance in Iowa, Lincoln and Waupaca counties involves bi‑weekly “tick dragging” and monitoring emergency‑room visits. State health experts recommend long sleeves, DEET or picaridin repellents, permethrin‑treated clothing, staying in trail centers, daily tick checks, and prompt removal of any attached ticks. Both jurisdictions stress that early detection and prevention are the most effective defenses against Lyme disease and other tick‑borne illnesses.