Ask the Doctors: Ticks can cause many diseases. How to check, what to watch for.

Dear Doctors: 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?

Answer: 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.

Though 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.

Perhaps the best known of the dozen or so tick-borne illnesses that are most common in the United States is Lyme disease, which is transmitted by the blacklegged tick.

Many tick-borne diseases are caused by bacteria and can be treated with antibiotics. Because ticks are so small and symptoms often overlap with a range of diagnoses, the challenge often is identifying the disease and its source.

Like tick paralysis, a frightening syndrome that tends to get a lot of attention whenever a case becomes public. But, while it’s a concern in livestock, tick paralysis is uncommon in humans. Though rare, it can be fatal, so a timely diagnosis is crucial.

The syndrome owes to the release of a neurotoxin discharged by the tick’s salivary glands during a bite, most often from a female tick, usually when she has been attached for several days.

Because tick paralysis is chemically induced, removing the tick is key to reversing the syndrome.

In the United States, the American dog tick and the Rocky Mountain wood tick are the most common cause.

Symptoms begin in the lower extremities, then gradually spread. They can include unusual or unexplained fatigue, muscle aches and sensations of tingling and numbness. As paralysis sets in, the victim might trip or stumble.

If the attached ticks are not found and removed, paralysis will continue to spread.

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.

When people from a tick-dense area develop 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.

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.

Dr. Eve Glazier and Dr. Elizabeth Ko are internists who teach at UCLA Health.