Seabather's Eruption - Presentation

Presentation

The reaction is identified by severe itching around small red papules 1mm to 1.5cm in size located on areas of skin that were covered by water-permeable clothing or hair during ocean swimming. Initial swimmer exposure to the free-floating larvae produces no effects, as each organism possesses only a single undeveloped nematocyst which is inactive while suspended in sea water. However, due to their microscopic size and sticky bodies, large concentrations of larvae can become trapped in minute gaps between skin and clothing or hair. Once the swimmer leaves the ocean, the organisms stuck against the skin die and automatically discharge their nematocysts when crushed, dried out, or exposed to fresh water. This is why symptoms usually do not appear until the swimmer dries themselves in the sun or takes a freshwater shower without first removing the affected clothing.