Ticks and Humans in British Columbia

Pest Control Note 93-04, updated January 2003

• 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.

There is no need to fear or avoid tick-infested country. A few simple precautions, outlined in this pamphlet, will decrease the likelihood of tick bites.

The Rocky Mountain Wood Tick (Dermacentor andersoni)

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 Western Black-legged Tick (Ixodes pacificus)

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 BC over the last 6-8 years, and health authorities now believe that Lyme Disease carrying ticks may be present throughout the province. To date in British Columbia there have been over 60 confirmed cases of Lyme Disease. Of these, 20 cases had no record of travel outside of the province, and the disease is considered to have been contracted in BC. For more information on Lyme Disease, see the BC Centre for Disease Control web site.

Other Ticks

Winter Tick

Removal of Attached Ticks

Personal Protection

The following precautions will decrease the likelihood of tick attachment. 

1. 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. 
2. If possible, avoid game trails or old roads overgrown or closely lined with vegetation. Tick levels may be high in areas frequented by animals. 
3. When resting, sit on a bare rock, a ground sheet, or a vegetation-free area instead of stretching out on vegetation. 
4. 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. 

1. General symptoms of fever headache, muscle and joint pains, fatigue or weakness of the muscles of the face. 
2. Skin rash, especially one that looks like a "Bull's Eye". It may or may not be where the bite was. 
3. 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.

Area Tick Control

Removal of brush and other vegetation may also reduce the number of ticks along trails or in picnic areas.

Revised by:
H.G. Philip, Entomologist
Crop Protection Program
Plant Industry Branch
Kelowna

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