Rash Caused by Jellyfish Larva, Not “Sea Lice” at Beaches in Florida

Purple flags — a warning for potentially dangerous marine life — are posted to warn beachgoers because of an outbreak of abnormally high number of cases of an itchy rash caused by a larval form of the Thimble Jellyfish.

“Sea Lice” infestation is a misconception about an organism that causes skin eruption among sea bathers near Florida, and some remote areas as far away as the Philippines, Thailand, Brazil and New Zealand.

The actual suspected organism, the larval form of Linuche unqui culata, also known as a “thimble jellyfish,” is responsible for the outbreaks in South Florida and the Caribbean. The larval form is barely visible except under excellent lighting, and looks like a black speck of finely ground pepper. Bathing suits or T-shirts worn by swimmers apparently trap variable the larvae, which causes the larvae to shoot stingers from a “skin” of nematocysts. Individuals are commonly stung up to 200 times under the material of a bathing suit.

Dermatitis associated with the stings is usually detected between four and 24 hours after exposure.

Associated symptoms …

Rash, bumps, blisters, itching, difficulty in sleeping, nausea, vomiting, diarrhea, headache, weakness, fever, chills, muscle spasms, arthralgias, and a sense of malaise.

Some symptoms could be caused by ingestion of infected seawater or by a systemic immune response to the stings.

Fever (temperatures greater than 101 degrees F) have been reported among children11 years of age or younger. The highest recorded temperature was 103.4°F.

Treatment …

Remedies reported include using calamine lotion, a diphenhydramine and calamine (Caladryl) lotion, which should not be applied when an
oral antihistamine is being used to avoid overdosing toxic effects, especially in children.

Keeping the skin clean is also recommended to avoid secondary infections. Care should also be directed to confirm that other rash-causing diseases have not coincidentally caused the symptoms.

Prevention …

1. Use pool facilities and avoid the ocean when beach alerts warn of “Sea Lice” or seabather’s eruption

2. Don’t wear a T-shirt in the ocean water.

3. Sunscreen and tanning lotion may offer protection.

4. Change out of bathing suit as soon as exiting from ocean water.

5. Thoroughly wash bathing suits with detergent and dry with heat that the fabric can tolerate.

Outbreaks of seabather’s eruption occur intermittently between March and August, but peak during early April through early July.

Outbreaks of seabather’s eruption appear to be caused by shifts in South Florida’s currents, with the highest incidence of cases in areas as Palm Beach County, which includes the cities of West Palm Beach, Boynton Beach, Delray Beach and Boca Raton; and Northern Broward County, which includes the cities of Deerfield Beach, Pompano Beach, and Fort Lauderdale. These are locations where the Gulf Stream passes closest to shore. Other areas of the Florida coastline are affected by shifts in currents or by strong easterly winds which bring the larvae from the Atlantic Ocean waters closer to shore.

Seabather’s eruption has also been reported in the Bahamas, Bermuda, the Florida panhandle, and the Texas coast. Biologists believe the cases may eventually spread through the coastline of the Gulf of Mexico.

There are actual organisms known as Sea Lice that affect fish, but not humans.