Lyme disease: Prevention and risks
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- How Lyme disease spreads
- Preventing tick bites and Lyme disease
- Risks of getting Lyme disease
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How Lyme disease spreads
Lyme disease is caused by a bacterium called Borrelia burgdorferi, which is spread through the bite of infected blacklegged ticks. Infected blacklegged ticks need to be attached for at least 24 hours in order to transmit the bacteria that causes Lyme disease.
Most people get Lyme disease after being bitten by:
- nymphs, which are about the size of a poppy seed
- adult female ticks, which are about the size of a sesame seed
You may not notice a tick bite because ticks are tiny and their bites are usually painless.
Not all blacklegged ticks carry the bacteria that causes Lyme disease. Blacklegged ticks are infected with the bacteria when they feed on infected animals like:
- rodents, such as white-footed mice and chipmunks
People and other animals can get Lyme disease when an infected tick feeds on them for long enough to transmit the bacteria.
More than 40 different types of ticks live in Canada, but only 2 types spread the bacteria that can cause Lyme disease in people:
- blacklegged ticks
- western blacklegged ticks, common to British Columbia
Blacklegged ticks are most often found in or along the edge of forested areas. Tick habitats also include:
- leaf litter
- wood piles
- grass or herbs
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.
You can sometimes find blacklegged ticks in areas outside of where they're known to live. Always take precautions against tick bites when in wooded or grassy areas.
Preventing tick bites and Lyme disease
There's currently no Lyme disease vaccine available for humans. However, there are clinical trials taking place in Europe and the U.S.
The best way to protect yourself from tick-borne diseases is to prevent tick bites. Check your provincial public health authority to find out where infected ticks are most likely to be found.
Before you go into a tick habitat
- Wear light coloured, long-sleeved shirts and pants to spot ticks easily.
- Tuck your shirt into your pants, and your pants into your socks.
- Wear closed-toe shoes.
- Apply insect repellent containing DEET or Icaridin to clothing and exposed skin (always follow label directions).
- Wear permethrin-treated clothing (always follow label directions).
While you're in a tick habitat
- Walk on cleared paths or trails.
- Keep children and pets from wandering off paths.
- Avoid using trails created by animals (such as deer and moose), as ticks are often found on the grass and plants along these trails.
Before you go indoors
Do a check for ticks on yourself and your:
- Outdoor gear, such as backpacks
When you're indoors
- Shower or bathe as soon as possible, as it can help you find unattached ticks. If you don't shower or bathe, do a full-body tick check on yourself and your children.
- If you find an attached tick, remove it as soon as possible.
- To kill unattached ticks on your clothing, put dry clothes in a dryer on high heat for at least 10 minutes. If your clothes are damp, you may need to dry them for longer.
- If you wash your clothes, use hot water and dry on high heat. Ticks can survive a cold/warm wash cycle.
Reducing tick habitats around your home
Blacklegged ticks thrive in damp, shady environments. They can't survive for long in dry, sunny areas. To create an environment that's unfavourable for tick survival:
- mow the lawn regularly to keep the grass short
- remove leaf litter, brush, long grass and weeds:
- at the edge of the lawn
- around stone walls and woodpiles
- prune shrubs and trees to allow sunlight to filter through
- create a 1-metre or wider wood chip, mulch or gravel border between your lawn and:
- stone edges
- seal stone walls and other openings to help prevent animals such as deer, mice and other rodents from bringing ticks into your yard
- place patios, decks and children's playground sets in sunny areas of the yard and away from yard edges
- place playground sets on a mulch or wood chip surface
Talk to your veterinarian about tick-prevention products for your pets, as they can also bring ticks into your yard or home.
Risks of getting Lyme disease
You should always take precautions against tick bites when taking part in higher-risk activities, such as:
- working in habitats suitable for ticks, such as:
- participating in recreational activities where ticks may be present, such as:
- fishing (from land)
Animal to person
Humans cannot be directly infected with the bacteria that causes Lyme disease from other animals.
However, pets can carry ticks into your yard or home, which could increase your chance of being bitten.
Consult with a veterinarian before using any medication or substance (such as insect repellent) on your pets.
Person to person
There's currently no evidence that Lyme disease can spread from person to person through physical contact.
There have been no reports of Lyme disease cases linked to blood transfusions. For more information, consult Canadian Blood Services.
You should always take steps to prevent tick bites, including while pregnant.
Contracting infectious diseases during pregnancy can be of concern 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're pregnant, it's safe to use:
- approved insect repellent containing DEET or Icaridin (always follow label directions)
- permethrin-treated clothing (always follow label directions)
If you think you may have Lyme disease, talk to your health care provider as soon as possible.
For more information, consult the Society of Obstetricians and Gynaecologists of Canada.
There have been no reports that Lyme disease can be passed to your baby through breast milk. Consult your health care provider if you're breastfeeding and concerned about Lyme disease.
Posters to share
- Top 10 tick hiding spots on your body
- Enjoy the outdoors, without a tick
- Protect your pets from ticks and Lyme disease
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