Seabathers eruption (also known as sea lice) is a form of dermatitis that appears on covered areas of the skin (under bathing suits, shirts, and long hair), rather than on exposed areas as with swimmers itch, and is associated with bathing in coastal waters. Episodes reported in Long Island waters are believed to be caused by the larval form of the sea anemone (Edwardsiella lineata). A similiar condition that occurs regularly off the coast of Florida (also termed "seabathers eruption") is caused by the larval form of the thimble jellyfish (linuche unquiculata), locally referred to as sea-lice. In either case, the dermatitis results when the tiny larval forms (the size of a pin head) are trapped underneath bathing suits or in the hair of the bather. Each larvae is equipped with a number of nematocysts (stinging cells), that can be triggered by simple mechanical pressure or by osmotic changes that occur with evaporation or when rinsing off with freshwater.
The dermatitis that results from the nematocyst sting appears within a matter of hours, and can be intensely pruritic (itchy). As with swimmers itch, the rash usually subsides within a week, depending on its severity and the individuals sensitivity. Treatment of sea-bathers eruption is the same as with swimmers itch. If itching is severe, contact your health care provider who may prescribe lotion or creams to lessen your symptoms.