Auckland swimmers’ rashes due to microscopic jellyfish

Rashes reported by Auckland swimmers during January 2012 have been confirmed by Auckland Regional Public Health Service (ARPHS) as being due to microscopic jellyfish stings. ARPHS advises swimmers to take care at Hauraki Gulf beaches. The microscopic jellyfish - or hydromedusae, whose number increase as the water warms - can cause a red, raised, itchy or painful rash, which tends to mainly affect areas covered by togs or clothes, rather than uncovered areas (sea lice tend to bite uncovered areas). The jellyfish are transparent and too small to be seen and get caught inside swimwear. On leaving the sea, they become trapped and sting covered areas. A tingling sensation may be felt first; several hours later, a rash develops. Medical Officer of Health, Dr Simon Baker says, “The only guaranteed way to prevent being stung is to avoid bathing at affected beaches [or swim in a freshwater pool]. We have had reports from Long Bay, Milford and Takapuna beaches, although it is likely that this problem extends all along the Hauraki Gulf.” If swimming in the sea:  

• avoid large, baggy clothes in the sea (but stay Sunsmart) 
• after swimming, remove swimwear promptly and shower – especially areas covered by your swimwear 
• don’t towel the area before showering – this will just set off the stinging 
• if you develop a rash, have a shower and get into cool, loose clothing; calamine lotion may help 
• if the rash persists, visit your local pharmacy – mild steroid creams like hydrocortisone can be helpful, as can antihistamine tablets 
• if problems are severe or persist or worsen, see a doctor 
• don’t put the swimwear back on until laundered properly, as the jellyfish can still sting even after they are dead. 
  

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