Seabather's eruption in Adult
Some refer to seabather's eruption as "sea lice," although this is a misnomer, as true sea lice are skin parasites of fish that do not affect humans.
Envenomation, primarily triggered by pressure and friction, occurs when the larvae get caught beneath swimwear and stinging cells (nematocysts) discharge into the skin.
The condition typically presents within minutes to 1-2 days after patient emerges from seawater as a pruritic, urticarial, and/or papular rash in the distribution of their bathing suit or other areas of pressure including surfboard contact. Symptoms usually persist for 5-7 days but may persist for up to 2 weeks or longer. Some patients may develop fever, headache, malaise, and emesis (especially children). Conjunctivitis and urethritis may develop if exposure to those mucous membranes occurs. Systemic hypersensitivity reactions, including anaphylaxis, are rare in jellyfish envenomations. Rarely, the rash may recur within 2 weeks, and atopic individuals may have lesions for up to 6 weeks.
Risk factors include age younger than 16 years, a past history of seabather's eruption, and surfing. Showering without a bathing suit after seawater exposure has been found to be protective. Having a history of seabather's eruption increases the risk of future episodes, which supports the theory that this condition is due to underlying hypersensitivity. Some individuals are apparently immune, however, and do not develop a rash despite similar, repeated exposures in the same seawater as those who are symptomatic. No deaths have been reported.
T63.691A – Toxic effect of contact with other venomous marine animals, accidental, initial encounter
238534006 – Sea bather's eruption
Differential Diagnosis & Pitfalls
- Pseudomonas folliculitis – Also called hot tub folliculitis, may also be accentuated under swimwear.
- Patients with swimmer's itch (animal schistosomes) have lesions outside the bathing suit area.
- Seaweed dermatitis is more severe and leads to blistering and desquamation; it is also endemic to Hawaii, where seabather's eruption has not been reported.
- "Dogger Bank itch" (Bryozoa dermatitis) is an algae-induced seaweed dermatitis. This condition is found in dockworkers along the North Sea and the Mediterranean. The lesions are chronic and can be disabling.
- Rashes caused by other ocean-dwelling organisms (hydromedusae, crab larvae)
- Acute schistosomiasis – Heavy exposure to human schistosomes may result in acute schistosomiasis, which may be associated with urticarial rash, pruritus, limb edema, lymphadenopathy, fever, nausea, and diarrhea.
- Contact dermatitis
- Insect bites
- Mite dermatitis – Oak mite bites occur in the US Midwest; neck and torso bites may resemble seabather's eruption.