Montreal Hits Record High for Lyme Disease as Island Becomes Official Risk Zone

Lyme Disease Surge Linked to Climate Change and Local Exposure

Montreal public health officials have confirmed that the city reached an unprecedented milestone in 2025, recording its highest number of Lyme disease cases to date. A total of 161 cases were documented in the agency’s latest annual report, marking a significant increase from the 113 cases reported just one year prior. Most notably, nearly 38 per cent of these infections—61 cases—are believed to have occurred directly on the island of Montreal, reinforcing the city’s status as an endemic zone for the black-legged ticks that carry the bacteria.

Dr. Nicolas Sheppard-Jones, medical lead for infectious disease public health emergencies, noted that the rise is not unexpected given the northward migration of tick populations. Health experts point to climate change as a primary driver, as warming temperatures create more hospitable environments for ticks to thrive in urban gardens and parks. Previously, most cases seen in Montreal were imported from Ontario or the United States, but local transmission has now become the dominant trend.

Demographics and Hospitalization Risks

The 2025 data reveals that older adults are particularly vulnerable, with Montrealers aged 50 to 69 accounting for the largest share of infections. Children are not exempt, however, with 22 cases recorded in the 0-14 age bracket. While Lyme disease is often treated effectively with antibiotics, roughly six per cent of patients required hospitalization due to severe complications affecting the heart, joints, and neurological systems.

Interestingly, many patients were unaware they had been bitten; only 14 per cent reported seeing a tick on their skin. Activities as common as gardening and yard maintenance were cited by 39 per cent of those infected locally, highlighting that the risk extends beyond deep-forest hiking into residential backyards.

Prevention and Immediate Action

Public health officials are urging residents to adopt new habits to mitigate risk. Recommendations include wearing long clothing, using approved tick repellents, and staying on marked paths during outdoor activities. Experts emphasize the importance of a ‘tick check’ and showering within two hours of returning home to remove unattached ticks. If a bite is discovered, the tick should be removed carefully with tweezers without crushing the abdomen, and the incident should be reported via 811 to determine if preventative antibiotics are necessary.