Lyme disease is an infection caused by bacteria in the Borrelia family. The first symptoms of Lyme disease usually appear within 3 to 30 days after the bite. If left untreated, symptoms will progress over the course of the following weeks and months.
The most common symptom is reddening of the skin. It develops around the bite area, most frequently on the thighs, groin, armpits and torso. With every passing day, the rash spreads quickly, extending over 5 centimetres. In addition to the redness, other symptoms may occur:
- Muscle and joint pain
- Neck stiffness
Causes and triggers
Lyme disease is spread to humans through the bite of infected ticks. For ticks to develop, they must feed on animal or human blood. Their bites are usually painless and often go unnoticed. Before feeding, an adult tick measures between 1 and 3 millimetres, but can triple in volume when filled with blood, reaching the size of an apple seed.
Ticks that have not reached adulthood are known as nymphs, and can also transmit Lyme disease. At the nymph stage, they are very small and because they remain virtually undetected, they are able to stay attached to skin longer. Generally speaking, an infected tick must be attached to skin for 36 to 48 hours or more before it can transmit the disease to a human.
Ticks do not jump or fly. They are normally found in forests, woods, tall grasses and piles of dead leaves. Ticks that transmit Lyme disease are found throughout Canada, the United States and in other countries.
|Adult ticks at various stages of engorgement.|
If you were recently bitten by a tick, a preventive treatment may be prescribed. If symptoms appear, treatment involves antibiotics that must be prescribed by a doctor. The nature and duration of the treatment depends on the stage of infection and symptoms.
- When walking in the woods, stay on the trail;
- When walking in tall grasses or wooded areas, wear pants and tuck them into your socks, a long-sleeved shirt that is fitted at the wrists and tucked into your pants, and closed shoes and a hat;
- Wear long and light-coloured clothing to make it easier to spot ticks;
- Use insect repellent containing DEET or icaridin on exposed parts of the body, avoiding the face;
- Inspect yourself, others, pets and equipment for ticks when returning from a risk area;
- Remove the tick from the skin as quickly as possible using tweezers or a special tick removal tool. Grasp it as close to the skin's surface as possible (not by its body) and pull upward without twisting.
When should I see a medical professional?
If you develop one or more of these symptoms within 3 to 30 days of participating in an outdoor activity in a risk area, and think it may be a symptom of Lyme disease, consult a health professional. If you noticed a bite, be sure to notify the health professional.
For more information:
Public Health Agency of Canada