Lyme disease is caused by the bacteria called Borrelia burgdorferi.
Lyme disease is an infectious disease spread through the bite of infected ticks. There are two types of ticks that can spread Lyme disease in Canada:
Ticks need blood to survive, so they attach on animals and humans to feed. Ticks become infected with Lyme disease bacteria by feeding on infected wild animals, such as:
Once infected, ticks can spread the bacteria to humans and pets, particularly dogs. In most cases, the infected tick must attach and feed for at least 24 hours before the bacteria can be transmitted.
Most humans are infected through the bite of immature ticks that are approximately the size of a poppy seed, called nymphs. Adult ticks, approximately the size of a sesame seed, can also spread Lyme disease. Ticks are very small and their bites are usually painless, so you may not know that you have been bitten.
Blacklegged ticks are most often found in wooded or forested areas, in leaf litter or on shrubs and tall grass in some parts of Canada. Blacklegged ticks in at risk areas of southeastern and south-central Canada are more commonly infected.
Information taken from; https://www.canada.ca/en/public-health/services/diseases/lyme-disease/causes-lyme-disease.html