Description
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.
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 monitoring data, Ixodes scapularis ticks are established in certain areas of all Québec regions, with the exception of the following regions:
- Côte-Nord;
- Nord-du-Québec;
- Nunavik;
- Terres-Cries-de-la-Baie-James.
However, among areas with established tick populations, the risk of exposure to Lyme disease varies. For more details on these areas, consult the map of the current distribution of Ixodes scapularis ticks (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.
Over the past 15 years, the number of reported cases of Lyme disease in Québec has risen sharply, as has the proportion of people who acquired their infection in the province, from around 50% in 2013 to almost 86% in 2023.
The number of Lyme disease cases reported in Québec since 2021 is as follows:
- 709 cases in 2021;
- 586 cases in 2022;
- 652 cases in 2023.
The fact that Québec winters are not as cold as they used to be could partly explain the increase in previous years. A milder climate would allow ticks to survive and develop more easily. Ticks are active at 4°C and above. They reach their optimum level of activity at around 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.
Transmission
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.
After any outdoor activity that may allow exposure to ticks, it's important to check your skin for ticks and remove them as soon as possible. To find out how to proceed, consult the page Removing a tick if bitten. Then call Info-Santé at 811.
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.
Protection and prevention
The best way to avoid catching Lyme disease is to avoid tick bites during outdoor activities. To find out how to prevent Lyme disease, see Protect yourself and your animals from mosquito and tick bites page.
Transmission
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.
Redness caused by Lyme disease. © Centers for Disease Control and Prevention (CDC)
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.
If you develop a rash after possible exposure to ticks, measure the diameter of the rash. You can also draw the outline with a pencil and take a photo to check later if it spreads.
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
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.
Treatment
Preventive treatment
If you've been bitten by a tick in Canada or the U.S., remove and store it, then call Info-Santé 811 or consult your pharmacist promptly. Depending on the situation, you may be prescribed an antibiotic as a preventive measure.
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.
Other tick-borne diseases
Other diseases, such as anaplasmosis and babesiosis, can be transmitted by the same ticks that cause Lyme disease.
In Québec, these diseases are emerging. A few cases have been reported in recent years.
Anaplasmosis
Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum.
It has been a mandatory notifiable disease in Québec since 2019. The first peak in reported cases was in 2021, when 47 cases were reported, 35 of them in residents of the Estrie region. In 2023, 46 cases were reported, 40 of which were acquired in Québec. The regions most affected are Estrie, with 31 cases acquired in this region, and Montérégie, with 7 cases acquired in this region.
Symptoms can develop from 5 to 21 days after the bite of an infected tick.
These symptoms may include the following:
- fever, chills
- headaches;
- muscle and joint pain.
In rare cases, other symptoms may appear, such as:
- nausea, vomiting, diarrhea, loss of appetite;
- redness of the skin;
- coughing.
If left undiagnosed and untreated, the disease can become more severe, leading to respiratory problems, clotting disorders and, in some cases, death.
People at greater risk of developing a severe form of the disease are:
- people aged 65 and over
- people with weakened immune systems.
Babesiosis
A few cases of babesiosis have been reported among Québec residents, but the disease remains very rare. In 2023, three cases were reported, only one of which was acquired locally.
Babesiosis is caused by a microorganism called Babesia microti, which infects red blood cells. Many infected people may experience no symptoms at all. Some may experience flu-like symptoms, such as:
- fever, chills, sweating;
- muscle pain;
- loss of appetite;
- nausea;
- fatigue;
- possible jaundice.
People at greater risk of developing a severe form of the disease are:
- people aged 50 and over
- people who have lost their spleen;
- people with weakened immune systems
In healthy people, symptoms usually disappear within a week.
The best way to prevent these diseases is the same as for Lyme disease: avoid tick bites. To find out more, see Protecting yourself and your pets from mosquito and tick bites.
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
Institut national de santé publique du Québec - eTick (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
CISSS de la Montérégie-Centre - Ticks in a changing climate
CISSS de la Montérégie-Centre
Last update: July 11, 2024