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Lyme disease


Lyme disease is transmitted by the bite of a tick that carries Borrelia burgdorferi bacteria. It can affect humans and animals. To learn more, consult the page Lyme disease in animals.

This disease was first described in 1977 following an outbreak of arthritis in children living in the town of Lyme, Connecticut in the United States.

Ticks that can transmit Lyme disease are now found in North America, Europe, Asia and North Africa.

In Canada, ticks that can transmit Lyme disease are found in parts of southern Manitoba, Ontario, Québec and British Columbia and parts of New Brunswick and Nova Scotia. For more information, see the Government of Canada web page Lyme disease: Prevention and risks This hyperlink will open in a new window..

Lyme disease in Québec

There are a dozen species of ticks in Québec. Since ticks can be transported by birds, they are found in almost all regions of Québec. However, not all ticks carry the bacteria. The only species that can transmit Lyme disease in Québec and northeastern North America is the Ixodes scapularis tick, also called the “deer tick” or “blacklegged tick”.

In Québec, according to available surveillance data, Ixodes scapularis ticks are established in the following areas:

  • Estrie
  • Lanaudière
  • Mauricie-Centre-du-Québec
  • Montérégie
  • Montréal
  • Outaouais
  • Laval
  • Laurentides

For more details on risk areas, see the risk maps for Lyme disease This hyperlink will open in a new window. (in French only).

Since diagnosing Lyme disease can be difficult in some cases, the actual number of cases is probably higher than the number of cases reported. However, in Québec, Lyme disease has been a reportable disease (MADO) since 2003. Therefore, doctors and laboratory managers who diagnose a case of Lyme disease must inform the public health authorities. This system allows us to track the progression of this disease in Québec.

Since 2011, there has been a significant increase in the number of Lyme disease cases reported to the public health authorities in Québec as well as an increase in the proportion of cases that acquired their infection in the province. This proportion has increased from around 50% in 2013 to close to 90% in 2022.

The number of cases of Lyme disease reported in Québec since 2014 is as follows:

  • 125 cases in 2014
  • 160 cases in 2015
  • 177 cases in 2016
  • 329 cases in 2017
  • 304 cases in 2018
  • 500 cases in 2019
  • 274 cases in 2020
  • 709 cases in 2021
  • 586 cases in 2022

The fact that Québec winters are less cold than they used to be partly explains the increases before 2020. The warmer climate enables the ticks to survive and grow more easily. In fact, ticks are active at 4 °C and reach their optimum level of activity at about 25 °C.

Ticks and tick bites

Ixodes scapularis ticks live primarily in humid places such as forests, wooded areas, tall grass, gardens, landscaping and piles of dead leaves.

Ticks can be found at various stages of development (larva, nymph, and adult) in the same area throughout the year.

At each of these stages, ticks must feed on animal or human blood to go on to the next stage.

Before feeding, ticks can vary in size between 1 and 3 millimetres. Ticks can triple in volume when filled with blood, which makes them easier to detect in case of bites. Nymphs are smaller (the size of a poppy seed), often go unnoticed and generally stay attached to the person’s skin longer before they are detected. They are more active in the spring and summer months. Adult ticks are the size of a sesame seed, which makes them easier to detect, and are more active in fall.

After outdoor activity that may allow exposure to ticks, it is important to examine your skin to detect the presence of ticks and remove them as soon as possible. To know how, see the Removing a tick after a bite page.


Lyme disease is spread only through a bite from a tick that carries the Borrelia burgdorferi bacteria. After a tick bite, the risk of developing Lyme disease is very low if the tick remains attached to the skin for less than 24 hours, even if you were bitten in a high-risk sector. However, the risk increases if the tick remains attached for longer. It is, as a result, vital to remove the tick from your skin as quickly as possible. For more information, visit our page Removing a tick after a bite.

Ticks can cling to any part of the human body. They are often found in areas that are difficult to inspect, such as:

  • The groin
  • The navel
  • The armpits
  • Inside or around the ears
  • Behind the knees
  • The bottom of the buttocks
  • The lower back
  • The scalp

Pets who go outdoors can also bring ticks into the home.

People with Lyme disease can contract it again.

Lyme disease cannot be transmitted from an infected animal to a human or through contact between two people.


Tick bites are usually painless and often go unnoticed.

Lyme disease symptoms can vary from person to person. It is important to watch for symptoms so that the disease can be detected and treated quickly.

The first symptoms of Lyme disease usually appear 3 to 30 days after being bitten by a tick that carries the bacteria.

The most common symptom is a skin rash that is not usually painful or itchy. It develops at the site of the bite, most frequently on the thighs, groin, armpits or torso. It may sometimes occur in areas that are hard to see, such as behind the knees, the lower buttocks or back, the scalp, behind the ears, the eyebrows, the bellybutton or between the toes. A rash develops in 60% to 80% of cases of infection but is not always noticed. It is present for at least 48 hours and expands rapidly until it is over 5 centimetres in diameter. The rash may be circular or look like a bull’s eye. It is sometimes very pale and its edges may be poorly defined.

Some people also experience fatigue, fever and muscle aches.

If the disease is not detected and treated quickly, the bacteria can spread in the blood and cause other symptoms, which develop in the weeks and months after the bite. These symptoms may, for example, include:

  • The appearance of several expanding rashes, with little or no pain or itching
  • Facial paralysis, numbness in a limb, neck pain, severe headaches
  • Swelling in one or more joints (for example, the knee); it is usually painless
  • Chest pain, palpitations or dizziness

When to seek medical help

If you develop a rash after possibly being exposed to ticks, measure the diameter of the redness. You can draw around the rash with a pen and take a photo. to check later if the rash expands.

Call Info-Santé 811 or see a doctor if any of the following applies to you:

  • The rash is 5 cm in diameter or larger
  • The rash lasts more than 48 hours
  • You experience one or more other symptoms of Lyme disease within days, weeks or months after engaging in outdoor activities where you may be exposed to ticks

If you have noted a bite, provide the information you noted concerning the bite:

  • The part of the body that was bitten
  • The date and the place you were when you were bitten

If you consult a doctor, bring the tick, if possible, in a closed container such as a pill container.


Preventive treatment

If you were bitten by a tick in certain areas of Estrie, Mauricie-et-Centre-du-Québec, Montérégie, Outaouais or elsewhere in Canada or the United States, remove and keep the tick, then call Info-Santé 811. The nurse will tell you if you need to consult a health professional. Depending on the assessment of the situation, an antibiotic may be prescribed to you as a precaution.

Treatment of the disease

Lyme disease can be treated with antibiotics prescribed by a doctor. The nature and duration of the treatment depends on the stage of infection and symptoms.

People who are treated usually experience a quick and full recovery from the disease. Some, however, may have symptoms for several months after the treatment.


If the disease is not detected and treated quickly, it can cause problems in other organs or parts of the body, for example:

  • Joint problems
  • Heart problems
  • Neurological problems

These problems may appear within the weeks or months after you are bitten. 

Protection and prevention

Ticks do not jump, do not fly and do not drop from a height (for example, from a branch). They can, however, cling to you or your pet when you are in contact with plants in a garden, in landscaping, in the forest, in wooded areas and in tall grass. The best way to prevent Lyme disease is to avoid tick bites during outdoor activities such as gardening, walks in the forest, golf, hunting, fishing, camping, etc.

No vaccine is currently available to protect humans against Lyme disease.


How to avoid tick bites

  • Take your walks preferably on trails and avoid tall grass.
  • Use insect repellent on every exposed part of your body, avoiding your face. Closely follow the instructions for using mosquito repellent.
  • Wear a hat, closed shoes, a long-sleeved shirt and long pants.
  • Tuck your shirt into your pants.
  • Tuck your pants into your socks or boots.
  • Wear bright-coloured clothing during your walks. Clear colors make ticks more visible.

After outdoor activities, to spot a tick

  • Examine your entire body.
  • Take a bath or a shower as soon as possible, ideally within 2 hours after the outdoor activity, to check for the presence of ticks. This will also allow you to remove ticks not solidly attached to the skin.
  • Have another person help you or use a mirror to examine the least visible parts, such as the back. Also use shower time to examine your kids.
  • Carefully inspect your belongings (backpack, coat, etc.). This precaution seeks to avoid introducing a tick into your home, where it could bite a person or a pet.
  • Eliminate ticks on your clothes by putting them in the dryer at high temperature for 10 minutes. If your clothes are too dirty to be put in the dryer directly, wash them in the machine with hot water, ideally for at least 40 minutes. Then put them in the dryer at high temperature for at least 60 minutes. The clothes must be completely dry.
  • Also inspect your pets as they may bring ticks into your house. If you find ticks on a pet, remove them and consult a veterinarian if necessary. To obtain information and recommendations regarding ticks on your pets, consult the page Lyme disease in animals.

If you find a tick, remove it by following instructions indicated in Removing a tick after a bite.

To reduce the presence of ticks in your surroundings

  • Cut tall grass and undergrowth around your house, and mow your lawn
  • Remove dead leaves, undergrowth and weeds from your lawn, around wood supplies and the shed
  • Place wood chip or gravel paths between lawns and wooded areas, patios and playgrounds. Paths should be at least 3 metres in width
  • Position play areas away from trees, in a sunny location
  • Stack wood neatly in a dry, sheltered area. This can deter rodents, which attract ticks. Rid your yard of old furniture and items

Useful websites

You can use the following tools to help you identify Ixodes scapularis ticks (“deer tick” or “blacklegged tick”):

  • Detailed description of the Ixodes scapularis tick This hyperlink will open in a new window.
    Institut national de santé publique du Québec
  • eTick This hyperlink will open in a new window. (online tick monitoring program)
    Bishop’s University, in collaboration with the Laboratoire de santé publique du Québec (LSPQ) and the Public Health Agency of Canada
    Citizens can submit photos of ticks collected from themselves, their pet or in the environment to the web platform. People who submit photos will be given the name of the species of the tick collected, information about the medical relevance of the species in question and what to do after a tick bite. However, this procedure does not identify whether or not the tick carries the bacteria.
  • Modifying Your Landscape to Reduce Your Risk of Getting Lyme Disease This hyperlink will open in a new window.
    CISSS de la Montérégie-Centre

Last update: July 6, 2023


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