Ontario sees surge in Lyme disease as tick season peaks

Warmer weather and climate‑related changes are expanding tick populations across Canada, with the blacklegged (deer) tick most closely monitored for Lyme disease. In Ontario, the number of reported human cases jumped from 144 in 2009 to 7,105 in 2025, highlighting a rapid spread that now threatens farmers who encounter ticks on livestock, pets and wildlife.

Experts advise outdoor workers and the public to wear treated clothing, apply DEET or icaridin repellents, keep yards trimmed, and control rodent and deer numbers. Frequent tick checks on people and animals are recommended, as transmission can occur in less than 24 hours. Early symptoms may include flu‑like illness, fever, fatigue, joint pain, and sometimes a bull’s‑eye rash. Doxycycline remains the standard treatment when administered promptly.

Public health officials emphasize that the rising tick season calls for coordinated prevention efforts among agricultural communities, researchers and citizens to curb the spread of Lyme disease.