Okay, MD consult forgive me for spreading the news of this, but being from colorado, I am putting the power of knowledge in the hands of the people who read this unbiassed :) blog.
Tick paralysis is easily treated but often missed
August 23, 2010
By Bruce Jancin |  |
| A dorsal view of a male Rocky Mountain wood tick, Dermacentor andersoni: This tick species is a North American carrier of Rickettsia rickettsii, which causes Rocky Mountain spotted fever. (Photo Courtesy of James Gathany/CDC) |
VAIL, Colo. (EGMN) – Tick paralysis is often misdiagnosed – with potentially dire consequences – as one of the other diseases that cause an acute ascending paralysis with preserved mental status.
The arthropod-inflicted paralysis is most often confused with Guillain-Barré syndrome. Other causes of an acute ascending paralysis with preserved mental status include spinal cord tumors and acute poliomyelitis. Botulism, in contrast, causes a descending paralysis with preserved mental status, Dr. Sean O’Leary said at the annual conference on pediatric infectious diseases, which was sponsored by the Children’s Hospital, Denver.
Conducting a thorough search for an embedded tick is essential in a patient with an acute ascending paralysis with preserved sensorium, particularly when there is a history consistent with potential tick exposure. Treatment of tick paralysis is simple: remove the tick. Clinical improvement will follow within hours.
In unrecognized and untreated cases of tick paralysis, however, the fatality rate is about 10%, with death typically occurring just 18-30 hours after symptom onset, according to Dr. O’Leary of the Children’s Hospital and the University of Colorado, both in Denver.
Tick paralysis is more common in children than adults. The highest-risk group is young girls with long hair that can readily hide an engorged tick that’s had a blood meal. At 3 days after attachment, the tick (usually a female) begins secreting the neurotoxin that causes the paralysis. Symptoms appear 4-7 days after attachment. The peak time for tick paralysis is tick mating season: April through June.
The clinical scenario typically begins with loss of appetite and voice, followed by gait instability, ascending flaccid paralysis, excessive salivation, eye irritation, pupil asymmetry, and vomiting. Death usually is from respiratory failure. For more than half a century, there have been postmortem reports of ticks being found embedded in the skin of people who died suddenly of unexplained paralytic illnesses.
About 8% of the 870 named tick species have been associated with intoxication syndromes. The species that cause the most cases of human, dog, and livestock paralysis in North America are Dermacentor andersoni and D. variabilis, both of which are vectors for the rickettsial diseaseRocky Mountain spotted fever. In the United States, tick paralysis occurs most often in the Pacific Northwest and Rocky Mountain states.
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| Dr Sean O'Leary |
The tick toxin’s pathogenic mechanism isn’t fully understood. Australian investigators have reported that the toxin inhibits acetylcholine release at the neuromuscular synapse, but tick paralysis there is caused by Ixodes species, and it’s not clear that the same mechanism is at work in the paralysis caused by Dermacentor species, Dr. O’Leary said.
