Ask the Doctors 5/13

Dear Doctor: I read about a family whose little girl got paralyzed by a tick. How does that happen? There are a lot of ticks where we live, and even though we’re careful, somebody gets bitten every summer. Is getting paralyzed something new we have to worry about?

Dear Reader: There’s no denying that ticks are a problem throughout the world. These tiny arachnids, which feed on human and animal blood, are even present in Antarctica, where penguins and nesting seabirds become their hosts.

Although most of the estimated 900 species of ticks worldwide don’t pose a health threat to humans, the handful that do can spread some nasty diseases via their bites. Perhaps the best known of the dozen or so tick-borne illnesses that are most common in the U.S. is Lyme disease, which is transmitted by the blacklegged tick. Many tick-borne diseases are caused by bacteria and can often be treated successfully with antibiotics. But because ticks are so small – even the minuscule nymphs can cause illness – and because symptoms often overlap with a range of diagnoses, the challenge often becomes identifying the disease and its source.

Among tick-borne illnesses is tick paralysis. It’s a frightening syndrome that tends to get a lot of media attention whenever a case becomes public. The good news, though, is that, while it’s a concern in livestock, tick paralysis is uncommon in humans. When it does occur, it’s seen more often in children than adults. And although it is rare, it has the potential to be fatal, so a timely diagnosis is crucial.

The syndrome occurs due to the release of a neurotoxin discharged by the tick’s salivary glands during a bite, most often from a female tick, and usually when she has been attached for several days. Because tick paralysis is chemically induced, removing the tick is the key to reversing the syndrome. When someone from a tick-dense area develops the characteristic symptoms of this syndrome, they should be closely examined for ticks, especially on the scalp and at the hairline, in the armpits, and in the pubic area. In the U.S., the American dog tick and the Rocky Mountain wood tick are the most common cause.

Symptoms begin in the lower extremities and then gradually begin to ascend. They can also include unusual or unexplained fatigue, muscle aches and sensations of tingling and numbness. As paralysis begins to set in, motor control is affected. This causes the person to begin to trip or stumble when they walk. If the attached ticks are not found and removed, paralysis will continue to move upward, affecting the trunk and upper extremities. If it continues unchecked, facial paralysis, which includes the tongue, can occur. In the most extreme cases, convulsions and respiratory failure can lead to death. Within 24 hours of removing the tick, the paralysis typically begins to subside.

Wherever you live, and even if you only go out into the yard, always inspect yourself and your children thoroughly for ticks. Prompt removal can prevent not only tick paralysis, but also other tick-borne diseases.

Send your questions to askthedoctors@mednet.ucla.edu.