One Linuche mystery solved: All 3 stages of the coronate scyphomedusa Linuche unguiculata cause seabather's eruption

Background: Seabather's eruption (SBE) is a highly pruritic dermatosis affe cting swimmers and divers in marine waters off Florida, in the Gulf of Mexi co, and the Caribbean Sea. Its cause has been attributed to various organis ms but recently to the larvae of the schyphomedusa, Linuche unguiculata. Objective: We attempted to determine whether immature and adult Linuche cau se SBE. Methods: Episodes of SBE in the Cancun and Cozumel area of the Mexican Cari bbean were evaluated during the season of high tourism (January-June). This time corresponds to the moments in the life cycle when the three swimming stages oft unguiculata-ephyrae, medusae, and larvae-can be sequentially obs erved. Our methods include (1) observations by divers, biologists, and stud ents coinciding with stinging outbreaks and the onset of SBE; (2) serologic evaluation of individuals stung by L unguiculata; and (3) the demonstratio n of Linuche nematocysts on the affected skin. Results: All 3 swimming Linuche stages can cause SBE. Conclusion: The offending stages of Linuche can be identified by the cutane ous lesion's morphology and the time of year.