Lyme disease: Monitoring

On this page

• Monitoring of Lyme disease in Canada
• Monitoring of human cases
• Lyme disease risk areas
• Publications

Monitoring of Lyme disease in Canada

Canada monitors Lyme disease to:

• keep track of the number of human cases of Lyme disease
• identify areas where blacklegged and western blacklegged tick populations may be emerging
• identify the areas where people are most at risk of Lyme disease

To get as much information as possible, we work with:

• provincial and territorial public health authorities
• researchers and academics

Learn more about:

• Provincial and territorial public health authorities

Monitoring of human cases

Monitoring of human cases is based on reporting of Lyme disease cases by provincial and territorial public health authorities.

Between 2009 and 2024, provincial public health units have reported 27,463 human cases of Lyme disease across Canada.

Reported cases of Lyme disease include those that are locally-acquired and travel-related. The national surveillance case definition for Lyme disease, initially implemented in 2009, was revised in 2016 and in 2024. These updates may have impacted the surveillance data, and it is important to consider these changes when interpreting trends.

There’s underreporting because some cases are undetected or not reported. In addition, annual case counts fluctuate due to a combination of factors including:

• public health prevention efforts
• variations in weather affecting tick activity
• variations in human activity such as time spent outdoors or healthcare-seeking behaviors

All provinces and territories voluntarily provided available data over the 14-year period.

Learn more:

• National case definition: Lyme disease

Lyme disease risk areas

Blacklegged ticks are spreading to new areas in Canada in part due to climate change. They can also spread by travelling on birds and deer. You can sometimes find blacklegged ticks in areas outside of where they're known to live.

Ticks can be active whenever the temperature is consistently above freezing and the ground isn't covered by snow. You're most likely to encounter ticks during the spring, summer and fall. However, when conditions are favourable, ticks can be active at any time of the year. The best way to prevent Lyme disease is to protect yourself against tick bites. Always take precautions against tick bites when you're in wooded or grassy areas.

The Public Health Agency of Canada, in collaboration with provincial and territorial public health authorities and partners, uses tick surveillance data and reported Lyme disease cases to identify areas where:

• tick populations may be emerging
• people are most at risk of Lyme disease

Learn more about:

• Ticks in Canada
• How to prevent tick bites

Check if you're in a risk area. Enter the first 3 characters of your postal code or municipality in the filter field below.

Lyme disease risk areas map

The map in figure 1 displays areas where people are most at risk of Lyme disease.

Figure 1: Text description

This figure contains 5 cross-sections which display locations where the risk:

• from tick bites is known to occur
• for Lyme disease is possible

Hatched areas are locations where tick risk is known and are called risk areas.

Cross-section 1: Manitoba and Western Ontario

Risk areas can be found:

• on the western Ontario border, and
• across Manitoba, wherever there is suitable tick habitat below the 53rd parallel.

Cross-section 2: Southern Ontario

Risk areas can be found along the north shores of Lake Erie and Lake Ontario, and on the south shore of Lake Huron.

Cross-section 3: Southeastern Ontario and Southern Quebec

Risk areas can be found around Kingston in the Saint Lawrence valley that extend northeast towards Ottawa, locations covering:

• Montérégie, Montréal, Laval, and large parts of Estrie and Mauricie et Centre du Québec
• parts of Outaouais, Lanaudiére and Laurentides

Cross-section 4: Maritime provinces

In New Brunswick, risk areas can be found in the counties of:

• York
• Charlotte
• Sunbury
• Queens
• Saint John
• Kings
• Albert
• Westmorland
• Kent
• Carleton
• Northumberland
• Victoria

All of Nova Scotia is found to be a risk area.

Cross-section 5: Southern British Columbia

Risk areas can be found in:

• much of Vancouver Island and the coast of British Columbia facing Vancouver Island
• river valleys across southern British Columbia

Publications

• 2022

  • Lyme disease surveillance in Canada: Annual edition 2022
  • Lyme disease surveillance in Canada: Annual edition 2022 (infographic)

• 2021

  • Lyme disease surveillance in Canada: Annual edition 2021
  • Lyme disease surveillance in Canada: Annual edition 2021 (infographic)

• 2020

  • Lyme disease surveillance in Canada: Annual edition 2020
  • Lyme disease surveillance in Canada: Annual edition 2020 (infographic)

• 2019

  • Lyme disease surveillance in Canada: Annual edition 2019
  • Lyme disease surveillance in Canada: Annual edition 2019 (infographic)
  • Surveillance for Lyme disease in Canada: 2009 to 2019
  • Lyme disease surveillance in Canada: 2009 to 2019 (infographic)

• 2018

  • Lyme disease surveillance in Canada: Annual edition 2018
  • Lyme disease surveillance in Canada: Annual edition 2018 (infographic)