Tick paralysis - Definition

Tick paralysis is the only tick-borne disease that is not caused by an infectious organism. The illness is caused by a neurotoxin produced in the tick's salivary gland. After prolonged attachment, the engorged tick transmits the toxin to its human host. The incidence of tick paralysis is unknown.

Signs and Symptoms

The toxin causes symptoms within 2-7 days, beginning with weakness in both legs that progresses to paralysis. The paralysis ascends upward to trunk, arms, and head within hours and may lead to respiratory failure and death. The disease can present as acute ataxia without muscle weakness.

Diagnostic Tests

Diagnosis is based on symptoms and upon finding an embedded tick, usually on the scalp.

Treatment

Removal of the embedded tick usually results in resolution of symptoms within several hours to days. If the tick is not removed, the toxin can be fatal, with reported mortality rates of 10-12 percent.

Prevention

No vaccine is currently available for any tick-borne disease. Individuals should therefore take precautions when entering tick-infested areas, particularly in the spring and summer months. Preventive measures include avoiding trails that are overgrown with bushy vegetation, wearing light-colored clothes that allow one to see the ticks more easily, and wearing long pants and closed-toe shoes. Tick repellents containing DEET (N,N, diethyl-m-toluamide) are effective and can be applied to skin or clothing. Although highly effective, severe reactions have occurred in some people who use DEET-containing products. Young children may be especially vulnerable to these adverse effects. Permethrin, which can only be applied to clothing, kills ticks on contact.