Auckland Regional Public Health Service says microscopic jellyfish are the cause of rashes found on Auckland beach bathers this summer.
Medical Officer of Health Dr Simon Baker says, "Sea lice are fish parasites and do not bite humans. It is almost certain that the rash under swimwear is caused by hundreds, even thousands of small jellyfish stings.
When a bather drains their swimsuit, the jellyfish are trapped tightly against the skin, and their stinging cells release the toxin. If you think you’ve been stung, make sure you use the shower at the beach to wash off the jellyfish - rather than sit around in your wet togs. A saltwater shower works best, but freshwater is almost as good. Then, change out of your togs as soon as possible."
Swimmers are being urged to give their togs a good wash if they suspect they have been stung.
Auckland Regional Public Health Service also recommends that swimmers wear lycra togs instead of baggy clothing, as baggy clothing gives the jellyfish more material to grasp onto.
Children appear to be a common target for jellyfish, possibly due to their softer skin.
Jellyfish stings can cause a mild itchy but painful rash that can last a week.
Calamine lotion, antihistamines and mild steroid creams such as 0.5% or 1% hydrocortisone may be helpful but if symptoms persist or worsen, visit your doctor.