Tick Paralysis

Tick paralysis, also known as tick toxicosis, is a relatively uncommon form of human neuromuscular disorder; it is more of a problem in veterinary medicine

Tick paralysis occurs most often in Australia, South Africa, and North America. Although primarily a veterinary problem, it also affects humans. In North America, the pregnant female tick Dermacentor andersoni is largely responsible for cases of paralysis. The toxin resides in the salivary gland of the tick and blocks the peripheral motor neuron release of acetylcholine at the NMJ. Children are most often affected, girls more than boys, and dark-haired people more than light-haired people. Bites occur in the spring and summer months. The diagnosis should be considered in patients with symptoms and signs consistent with the disease who have recently traveled to a tick infested area.

Causes

Hard- and soft-bodied female ticks are thought to produce a neurotoxin capable of causing paralysis in children. Ticks attach to the skin to feed on blood. It is during this feeding process that the toxin enters the bloodstream.

Symptoms

• Begin after several days of tick attachment
• Ataxia, irritability, and lethargy are the first symptoms.

Signs

• Ascending flaccid paralysis ensues shortly after initial symptoms and progresses from hours to days. Affected muscles are areflexic.
• Paralysis eventually reaches the cranial nerves and respiratory muscles if not diagnosed and the tick removed.
• Patients may have paresthesias, but sensation remains intact.
• Sensorium is intact.
• Pupils are reactive.
• An attached tick is found.

Treatment

Removing the tick removes the source of the neurotoxin. Recovery is rapid following the removal of the tick.