II. Pathophysiology

  1. Salt water exposure
    1. Distribution
      1. Mexico
      2. Bermuda and Caribbean
      3. Eastern United States Coastline
        1. Florida
        2. Gulf States
        3. Long Island, New York
    2. Episodic outbreaks related to ocean currents
      1. Current carries Cnidaria larvae near shore
  2. Toxin injected by nematocyst
    1. Organism: Cnidaria larvae carry >200 nematocysts each
      1. Jellyfish larvae (e.g. Sea thimble)
      2. Man-of-war larvae
      3. Anemone larvae
      4. Fire Coral larvae
    2. Mechanism
      1. Larvae trapped within bathing suit (e.g. waistband)
      2. Larvae nematocysts are activated
        1. Skin contact
        2. Pressure
        3. Fresh water exposure
      3. Nematocyst forcefully injects toxin into skin

III. Symptoms and Signs

  1. Initial
    1. Stinging sensation on leaving water
  2. Minutes to hours (within 24 hours)
    1. Insect bit-like red pruritic Papules or wheals
    2. Papules (may coalesce)
  3. Constitutional Symptoms in severe cases
    1. Headache
    2. Fever
    3. Chills
  4. Provocative factors
    1. Prolonged wearing of contaminated swim suit
    2. Re-exposure can occur with contaminated suit
    3. Strenuous Exercise
    4. Fresh water exposure activates nematocysts

IV. Management

  1. Symptomatic for Pruritus
    1. Antihistamines
    2. Cool compresses
    3. Sarna or Calamine lotion
    4. Low to medium potency Topical Corticosteroids
  2. Severe cases
    1. Systemic Corticosteroids (i.e. Prednisone)
    2. Thiabendazole 1.5 grams bid for 2 days (adults)

V. Course

  1. Rash persists 3 to 7 days (6 weeks in severe cases)

VI. Differential Diagnosis

  1. Swimmer's Itch (Fresh water to exposed areas)

VII. Prevention

  1. Avoid recently affected beach areas
    1. Public health officials should be notified
  2. Clean swim suits and wet suits thoroughly
  3. Shower immediately after swimming

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