“Sea lice” aren’t like common head lice, but they’re just as annoying.
Found around beaches in Florida, sea lice—or beach lice—are actually small jellyfish. They often invade the waters off Florida during the summer.
Swimmers can’t spot the little jellyfish larvae, as they’re microscopic. They can sting just like a fully grown jellyfish, leaving a mark. The rash they cause is called sunbather’s eruption, experts have said.
“Outbreaks of seabather’s eruption occur intermittently between March and August, but they appear to peak during early April through early July,” says the Florida Department of Health. “Seabather’s eruption appear to be caused by shifts in South Florida’s currents, with the highest incidence of cases in such areas as Palm Beach County and Northern Broward County, where the Gulf Stream passes closest to shore.”
The News Herald reports the sea lice, which are no bigger than a speck of ground pepper, are almost invisible to the naked eye, but they leave an unmistakable sting. They’ve been reported along Walton County’s Santa Rosa Beach this week.
Scott Jackson, a sea grant extension agent in nearby Bay County, says some scientists have compared the larvae to specks of pepper. They typically float harmlessly in the water, but sometimes they get trapped inside swimsuits. That’s when they sting.
The rash, also called “ocean itch,” can last a few hours to a couple of days.
Parks and Recreation officials for Palm Beach County told ABC News: “Some people do experience a prickling sensation while in the water, though itching usually starts several hours after being in the water and lasts two to four days but can last as long as two weeks.”
Palm Beach County officials posted sea lice signs to warn swimmers when outbreaks occur.
They’re also found in Texas waters, namely around Galveston, KHOU-TV reported.
“These things are microscopic,” said Dr. A. Scott Lea of the University Texas Medical Branch in Galveston. “You don’t see them in the water, so it’s hard for a person to know they have been exposed until they are symptomatic. At this time of year, the eggs have hatched and the sea lice are out there.”
The Florida Department of Health says treating the rash with an antihistamine or hydrocortisone cream is a good idea.
Sea lice are the most active from the months of April until August, but they can be found throughout the year.
The Associated Press contributed to this report.