Tick paralysis is caused by a toxin released by certain species of ticks which can lead to paralysis in animals and rarely in humans. This paralysis is reversed upon tick removal. The species causing the most cases of human tick paralysis in Canada are Dermacentor andersoni (the Rocky Mountain wood tick) and Dermacentor variabilis (the American dog tick). Dermacentor andersoni is found throughout the province of British Columbia (BC). Other ticks such as Ixodes spp also can cause tick paralysis but this is very rare.

The disease is not reportable and official counts are not available. The BCCDC Public Health Laboratory receives consultations on tick paralysis in 0-2 human cases per year in BC. Most cases occur in the BC Interior region in the spring and summer. Children are more often affected than adults.

Symptoms begin after a female tick attaches to the skin and has fed for 5-7 days. Symptoms may include numbness and tingling in the face and limbs, fatigue, weakness, irritability, restlessness or muscle pains. Over several hours or days, this can progress to unsteady balance and then complete paralysis (affecting the whole body) starting from the legs and moving upwards, or partial paralysis (affecting only one body part, e.g. an arm or leg). Other features include double vision and difficulty swallowing and speaking.

Prolonged attachment of a tick to an animal or human can cause tick paralysis. The tick releases a toxin which disrupts the function of nerves. The toxin is found in its in saliva and is transmitted during tick feeding.

Respiratory difficulties and death due to respiratory muscle paralysis can rarely occur if the tick is not removed rapidly.

If this diagnosis is suspected, a meticulous examination should be done to look for a tick on the body, with special attention paid to the scalp, neck, ears, and the spaces between the fingers. Hair should be sifted through with a fine tooth comb. If a tick is found in an accessible location then it should be extracted carefully using proper methods (see "Tick Removal and Testing", section under Lyme Disease (Borrelia burgdorferi infection) -BCCDC ). If a tick is found in a location where proper removal can be difficult, then seek medical attention for removal. Rapid improvement once an attached tick is properly removed is diagnostic. The diagnosis can be delayed due to the rarity of the condition.

The treatment for tick paralysis is tick removal. Most patients with tick paralysis will recover or substantially improve within a few hours following tick removal.

Tick paralysis can be avoided by not walking through or brushing against vegetated areas where ticks are endemic. Bathing and self-examination for ticks after outdoor activities is recommended. Wearing long pants, long sleeved shirts, socks and enclosed shoes, as well as using insect repellant containing DEET, reduce a tick's chance of contacting the skin.