Seabather's Eruption

Updated: Mar 10, 2016
  • Author: Clarence William Brown, Jr, MD, FAAD; Chief Editor: William D James, MD  more...
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Overview

Background

Seabather's eruption was first described in 1949 as a pruritic papular eruption occurring in bathers off the eastern coast of Florida. Seabather's eruption is a highly pruritic, papular eruption that occurs underneath the swimsuit after extended exposure to seawater. Seabather's eruption results from a hypersensitivity to the larval form of the thimble jellyfish, Linuche unguiculata. [1] Most cases occur from March to August, but the incidence peaks in May and June. See the image below.

Seabather’s eruption. Courtesy of DermNet New Zeal Seabather’s eruption. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/arthropods/sea-bathers.jpg).

See Deadly Sea Envenomations, a Critical Images slideshow, to help make an accurate diagnosis.

See also the Medscape article Cutaneous Manifestations Following Exposures to Marine Life.

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Pathophysiology

Seabather's eruption is a cutaneous hypersensitivity reaction to contact with the larval form (planulae) of the thimble jellyfish, L unguiculata. The eruption typically occurs underneath the bathing garments, which are believed to trap the jellyfish larvae against the skin. Whether the discharge of venom by the trapped larvae plays an important role in the pathogenesis of the eruption remains uncertain. Factors that promote the discharge of venom by the larvae include wearing of bathing suits for prolonged periods following swimming, exposure to fresh water through showering, and mechanical stimulation.

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Epidemiology

Frequency

United States

The incidence of seabather's eruption is seasonal; the highest incidence occurs from May through August. This coincides with the warm gulf streams running along the Atlantic coastline of Florida and the corresponding spawn of thimble jellyfish larvae, which results in the high seasonal concentration of Linuche planulae. In 1997, Kumar et al [2] reported the occurrence of seabather's eruption in Palm Beach saltwater swimmers in May to be 16%.

International

Seabather's eruption has been reported in Mexico and the Caribbean and along the coast of Brasil. [3, 4]  The true prevalence of seabather's eruption along other international coastlines remains unknown.

Race

Seabather's eruption occurs independent of race.

Sex

Seabather's eruption has been noted with equal frequency in both sexes.

Age

No correlation between age and risk for developing seabather's eruption has been noted. The severity of symptoms, particularly the frequency of fever, is greater in children than in adults.

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Prognosis

Cutaneous eruptions clear in 2 weeks, with or without therapy. No deaths have been attributed to exposure to thimble jellyfish larvae.

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Patient Education

Educate patients about thimble jellyfish larvae during peak seasons in affected areas and the preventative role of showering with the bathing suit off following exposure to the seawater.

For patient education materials, see the Environmental Exposures and Injuries Center; Bites and Stings Center; and Jellyfish, Stingray, and Other Water Animal Bites/Stings Center, as well as Jellyfish Stings and Stingray Injury.

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