Ministry of Agriculture
Ticks and Humans in British Columbia
- The Rocky Mountain Wood Tick
- The Western Black-legged Tick
- Other Ticks
- Removal of Attached Ticks
- Personal Protection
- Area Tick Control
There are more than 20 species of ticks in British Columbia, but only three species normally bite humans. Although the bites may sometimes be painful and slow healing, there is little danger of disease provided they are removed promptly. Adult ticks are distinguished from insects by having eight legs rather than six. They cannot jump or fly and do not drop from trees. Ticks require blood as a source of protein for egg development. A few simple precautions outlined below, will decrease the likelihood of tick bites.
In British Columbia, this tick occurs in the interior dry belt from the United States border north as far as Williams Lake and eastward into Alberta. It is not found west of the Coast Range mountains. The Rocky Mountain wood tick is a three-host tick, a new host being sought for each one of its three feedings which occur over a period of 1 to 3 years. Usually rodents and other small animals serve for the first two feedings, and large animals such as deer, cattle, dogs, sheep and humans serve as the host for the last feeding. This tick is most frequently encountered between March and June, usually in open, rocky areas.
Rocky mountain wood tick female
The adult female is reddish-brown with a white "shield" near the front, and the similarly sized male is mottled-grey in colour. Both sexes "quest" for hosts by waiting near the top of grass and low shrubs, readily attaching to passing humans or animals that brush against them. Once on a host they climb upwards, giving rise to the erroneous observation that they have dropped from trees. If the quest is unsuccessful, the ticks return to the ground until the next spring. Ticks successful in finding a host attach their mouthparts to the skin by means of a rapidly hardening cement. Feeding females quickly increase in size, excreting a mass of black bloodwaste during the process. When they reach the size of a swollen raisin they drop to the ground and, after several weeks, lays a few thousand eggs and dies.
Although the Rocky Mountain wood tick is a known carrier of Rocky Mountain spotted fever, tularemia, and Colorado tick fever in the United States, these diseases rarely occur in Canada. However, in British Columbia this tick causes a disease in man and animals called tick paralysis.
The disease is characterized by increasing uncoordination and eventual collapse. The first symptoms, usually a numbness in the feet and legs causing difficulty in walking and standing, occur after a female tick has been feeding for about 5 days. The hands and arms are usually affected next and there is often partial paralysis of the throat and tongue muscles, resulting in difficulty swallowing and speaking. There is little pain and usually no fever. Complete recovery occurs when the tick is removed if paralysis has not progressed too far, but death may occur if the tick is overlooked. There is no known antidote for tick paralysis. The nature of the toxin, likely secreted by the female during feeding, is not known.
|Life Cycle of Dermacentor andersoni|
The red and black females and smaller black males attach to humans, deer, cats and dogs, becoming grey and bean-like in size as they feed. The bite is often painful and may result in a slow-healing ulcer. This tick does not cause paralysis; however, it is a carrier of the microorganism responsible for Lyme disease in North America. The organism which causes Lyme Disease, Borrelia burgdorferi, has been found in ticks collected from many areas of B.C., and health authorities now believe that Lyme Disease carrying ticks may be present throughout the province. For more information on Lyme Disease, see the B.C. Centre for Disease Control web site.
|Western black-legged tick (Ixodes pacificus)
Photo: Creative Commons, by Ryan Kaldari, licensed under CC0 1.0
Many other British Columbia ticks feed only on a narrow range of hosts such as squirrels, rabbits, groundhogs and birds. Probably the one most commonly encountered by man is the winter tick. It feeds on moose, deer, horses and cattle during the winter but, while it may brush off onto humans, it will not feed on man.
The brown dog tick is a reddish-brown species that attacks dogs, usually feeding around the ears and between the toes. It rarely feeds on humans. This species may be found around cracks and baseboards in homes after dropping off a dog.
Many methods have been developed over the years for removing feeding ticks which connect themselves to their host with small, barbed mouthparts. Ticks do not burrow under the skin. A number of the more drastic techniques such as using a hot cigarette, gasoline, or hot matches to induce the tick to detach itself are unreliable and may cause injury to the person involved. Ticks are most safely and effectively removed by a slow and gentle pull without twisting, using tweezers or fingers. This will normally remove the tick with the mouthparts attached. The wound should be treated with an antiseptic. See the BC Center for Disease control web site for further information on removal of ticks.
The following precautions will decrease the likelihood of tick attachment.
- Wear high boots or tuck pant cuffs into socks. Tuck shirt into pants. Do not wear short pants. Application of commercial insect repellents containing diethyl toluamide (DEET) to the pants may assist in repelling ticks.
- If possible, avoid game trails or old roads overgrown or closely lined with vegetation. Tick levels may be high in areas frequented by animals.
- When resting, sit on a bare rock, a ground sheet, or a vegetation-free area instead of stretching out on vegetation.
- Make daily examinations for ticks, paying particular attention to the pubic region, the base of the skull, and the scalp. Check the backs of everyone in the group and carefully inspect any children. Clothes should be closely examined for ticks, especially near the collar, after they have been hanging overnight.
If you have the following symptoms within days or weeks after being bitten by a tick, please report them to your family doctor immediately. Tell your doctor when and where you were bitten by a tick. If possible, keep any removed ticks and take them to your doctor who may need to have the ticks identified. Ticks can be stored in any sealed container in a fridge or freezer.
- General symptoms of fever headache, muscle and joint pains, fatigue or weakness of the muscles of the face.
- Skin rash, especially one that looks like a "Bull's Eye". It may or may not be where the bite was.
- In some cases paralysis may occur. The paralysis usually starts in the feet and legs and gradually works its way up to the upper body, arms and head. This paralysis can develop from within a few hours to several days.
Removal of brush and other vegetation may also reduce the number of ticks along trails or in picnic areas.
Updated July 2014