Lyme disease is an infection caused by bacteria in the Borrelia family, and 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.
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:
The best prevention is to avoid being bitten by an infected tick. Here are some precautions you can take to protect yourself:
- 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 (e.g., DEET) 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 (by its body) and pull upward without twisting.
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.
For more information:
Public Health Agency of Canada