Tick paralysis
From Wikipedia, the free encyclopedia
| ICD-9 | 989.5 | |
|---|---|---|
| DiseasesDB | 31779 | |
| MedlinePlus | 001359 | |
| MeSH | C21.613.127.857.707 | |
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.
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[edit] 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.
[edit] Pathogenesis
Tick paralysis is believed to be due to toxins found in the tick's saliva that enter the bloodstream while the tick is feeding. The two ticks most commonly associated with North American tick paralysis are the Rocky Mountain wood tick (Dermacentor andersoni) and the American dog tick (Dermacentor variabilis); however, 43 tick species have been implicated in human disease around the world.[1] Most North American cases of tick paralysis occur from April to June, when adult Dermacentor ticks emerge from hibernation and actively seek hosts.[2]. In Australia, tick paralysis is caused by the tick Ixodes holocyclus.
[edit] Diagnostic tests
Diagnosis is based on symptoms and upon finding an embedded tick, usually on the scalp.
In the absence of a tick, the differential diagnosis includes Guillain-Barre syndrome and botulism.
[edit] 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,[3] usually due to respiratory paralysis. The tick is best removed by grasping the tick as close to the skin as possible and applying firm stready pressure.[4]
[edit] 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.
[edit] References
- ^ Gothe R, Kunze K, Hoogstraal H (1979). "The mechanisms of pathogenicity in the tick paralyses". J Med Entomol 16: 357–69.
- ^ Dworkin MS, Shoemaker PC, Anderson D (1999). "Tick paralysis: 33 human cases in Washington state, 1946–1996". Clin Infect Dis 29: 1435–9.
- ^ Schmitt N, Bowmer EJ, Gregson JD (1969). "Tick paralysis in British Columbia". Can Med Assoc J 100: 417–21.
- ^ Needham GR (1985). "Evaluation of five popular methods for tick removal". Pediatrics 75: 997–1002.
