Lyme disease: Prevention and risks

On this page

• How Lyme disease spreads
• Preventing Lyme disease
• Risks of Lyme disease
• Lyme disease risk areas
• Subscribe to the Zoonoses Bulletin

How Lyme disease spreads

Lyme disease is caused by a bacterium called Borrelia burgdorferi, which is spread through the bite of infected blacklegged ticks (deer ticks) and western blacklegged ticks.

In most cases, infected ticks need to be attached for at least 24 hours to transmit the bacteria that causes Lyme disease.

You may not notice a tick bite because ticks are tiny, and their bites are usually painless.

Learn more about:

• Ticks and tick-borne diseases

Preventing Lyme disease

There's currently no vaccine to prevent Lyme disease. However, there are clinical trials taking place in Europe and the U.S.

The best way to protect yourself from Lyme disease is to prevent tick bites. Check your provincial and territorial public health authorities to find out where infected ticks are most likely to be found.

Learn more about:

• How to prevent tick bites
• Provincial and territorial public health authorities

Risks of Lyme disease

You may have a higher risk of Lyme disease infection if you:

• spend time outdoors in and near areas with trees, shrubs, tall grass or piles of leaves where ticks can be found
• have pets that go outdoors because they can carry ticks into your yard or home, which could increase your chance of a tick bite
  • talk to your veterinarian about tick prevention for your pets

Learn more about:

• Canadian Veterinary Medical Association

Pregnant people

You should always take steps to prevent tick bites, including while pregnant.

During pregnancy, it's safe to use:

• approved insect repellent containing DEET or Icaridin (always follow label directions)
• permethrin-treated clothing (always follow label directions)

Infections during pregnancy can be concerning for you and your baby. If you're pregnant and don't feel well, or are concerned about your health, talk to your health care provider.

Current evidence related to Lyme disease and pregnancy is limited.

While transmission of Lyme disease during pregnancy is possible, the risk of passing Lyme disease to a baby during pregnancy is considered very low.

If a pregnant person has Lyme disease, they can be safely and effectively treated with antibiotics. Early treatment reduces the risk of potential placenta infection and complications.

If you think you may have Lyme disease, talk to your health care provider as soon as possible.

Breast milk

There have been no reports that Lyme disease can be passed to a baby through breast milk. Consult your health care provider if you're feeding breast milk and concerned about Lyme disease.

Learn more about:

• Society of Obstetricians and Gynaecologists of Canada: Lyme disease and pregnancy

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.

Use our interactive map with your postal code, municipality or province to check if you're in a risk area.

Interactive map

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, expanding inland, 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

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The Zoonoses Bulletin is an email subscription list that will provide you with regular updates from the Public Health Agency of Canada regarding our work on zoonoses. Zoonoses are infectious diseases that can be spread between animals and people including those that can be spread through the bite of a tick or mosquito.

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