Sea Bather’s Eruption (Sea Lice)

CHAPTER 178

Sea Bather’s Eruption

(Sea Lice)

Presentation

Patients seek help because of an intense pruritic or painful eruption of red raised welts, sometimes like mosquito bites. They are at times confluent, appearing in areas that had been covered by swimwear (Figure 178-1). This will occur within a few hours after bathing in the Caribbean or off the coasts of Mexico, Florida, or Long Island during periods when “sea lice” are active. Exposed areas of skin are spared. Symptoms may have started as a tingling sensation while in the water, with itching and burning becoming more pronounced if a freshwater shower was taken while still wearing the same suit. Symptoms usually resolve spontaneously in a few days; however, some individuals (especially children) experience a more severe delayed hypersensitivity reaction occurring approximately 10 days after exposure. This rash extends to exposed areas of the body not previously affected, and victims may also experience severe itching, fatigue, fever, chills, nausea, and headache. Outbreaks occur between March and August, with a peak incidence in May.

Figures 178-1 A and B, Sea bather’s eruption with multiple edematous pink papules found in areas previously covered by a bathing suit. (A, From White G, Cox N: Diseases of the skin. St Louis, 2006, Mosby; B, from Bolognia J, Jorizzo J, Rapini R: Dermatology. St Louis, 2003, Mosby.)

What To Do:

At the onset of symptoms, the patient should remove the bathing suit before showering and, if possible, decontaminate the affected areas using vinegar for 30 minutes.

Inform the patient about the nature of this rash and that it will usually last for 3 to 5 days.

Prescribe a topical steroid in combination with a topical anesthetic to be applied tid to qid. Pramosone cream or lotion 1% and 2.5% is supplied in 1- and 2-ounce tubes and in bottles of 2, 4, and 8 fluid ounces.

Prescribe an oral antihistamine, such as hydroxyzine (Atarax, Vistaril), 25 to 50 mg qid, to help with itching.

If systemic symptoms are present or if the rash is extensive and severe, prescribe 4 to 5 days of a systemic steroid, such as prednisone, 60 to 80 mg qd (1 mg/kg).

Instruct the patient to wash swimwear in detergent and fresh water and to dry it before wearing it again, because nematocysts may remain in the bathing suit after drying. Without washing and drying, any unreleased nematodes can be triggered and discharged, producing lesions without additional exposure to ocean water.

Instruct the patient about future prevention, either by avoiding ocean bathing during known outbreaks or by immediately removing swimwear after sea bathing, cleansing the skin with vinegar (to prevent the triggering of nematocysts) and then showering. Showering with fresh water while still wearing swimwear may cause a discharge of nematocysts and worsening of symptoms.

Safe Sea Sunblock Jellyfish Sting Protective Lotion, sold by Seavenger (Walnut, Calif.) and available on Amazon.com, reportedly prevents stings from sea lice, stinging corals, and jellyfish. A 4-ounce bottle gives roughly four adult full-body applications, each giving approximately 1 hour of protection. One small randomized, controlled study demonstrated a relative risk reduction of 82% (95% confidence interval: 21% to 96%; P = .02). No sea bather’s eruption or side effects occurred.

What Not To Do:

Do not prescribe systemic steroids for patients in whom there are strong contraindications. This is a self-limiting condition.

Discussion

Sea bather’s eruption typically occurs 4 to 24 hours after exposure, although some persons may develop a “prickling” sensation or urticarial lesions while still in the water. The larval forms of certain sea anemones and thimble jellyfish, Linuche unguiculata, are implicated as the cause. Water flows through bathing suits and traps the larvae, which discharge nematocysts when they contact skin. Lesions also occur on uncovered skin surfaces subjected to friction, such as axillae and inner thighs. Surfers develop lesions on the chest and abdomen that were in contact with surfboards. Sea lice do not infest humans.

Cercarial dermatitis, or “swimmer’s itch,” is a different condition that occurs sporadically in fresh water as well as ocean water. It occurs in exposed skin rather than under bathing suits and is thought to be caused by an avian schistosome, Microbilharzia variglandis. An over-the-counter topical steroid is generally all that is required to treat this problem.

Only gold members can continue reading. Log In or Register to continue