Lyme disease is an illness caused by the bacterium, Borrelia burgdorferi, which can be spread through the bite of certain types of ticks.

Lyme disease in humans can have serious symptoms but can be effectively treated. Cases of Lyme disease have been reported in parts of Europe, Asia, and throughout much of North America.

How do people get Lyme disease?

The bacterium that causes Lyme disease is normally carried in mice, squirrels, birds and other small animals. This bacterium is transmitted to ticks when they feed on these infected animals and then to humans through the bites of the infected ticks. In British Columbia, the western blacklegged tick transmits Lyme disease while in other parts of Canada, the disease is spread by the blacklegged tick, sometimescalled the deer tick.

Lyme disease is not transmitted directly from person-to-person by means such as touching or kissing. Although dogs and cats can contract Lyme disease, there is no evidence that they can transmit the infection directly to humans. Pets can, however, carry infected ticks into your home or yard. Deer hunting may increase exposure to ticks due to the need to track through high grass and brush areas. However, Lyme disease cannot be contracted from eating deer.

What are ticks?

Though closely related to insects, ticks are actually a type of mite. Ticks vary in size and colour; blacklegged ticks are very small. Before feeding, adult females are approximately 3-5 mm in length and red and dark brown in colour; following a blood-meal, females can be as large as a grape. In the pre-adult stages, young ticks are smaller and lighter in colour, when unfed. Ticks are usually picked up when brushing against vegetation and once on bare skin they attach by their mouth parts.

There are established populations of the tick that transmits Lyme disease in Canada. Though western blackleggedticks are widely distributed in British Columbia, populations are largest in the lower mainland, on Vancouver Island and in the Fraser Valley. Established populations of blacklegged ticks, on the other hand, have been found in southern and eastern Ontario, southeastern Manitoba and parts of Nova Scotia.

Research has shown that blacklegged ticks can be found in all areas of Canada, even where tick populations have not been previously identified. It is presumed that these ticks are introduced into these areas by migratory birds. About 10% of these ticks are infected with the Lyme disease agent. While it is possible to be bitten by an infected tick anywhere in Canada, the chances of this occurring are considered low in areas where populations are not established.