Health effects of recreational exposure to Moreton Bay, Australia waters during a Lyngbya majuscula bloom

A survey of residents in an area subject to annual toxic cyanobacterial blooms was undertaken to examine potential health effects of cyanobacteria toxins. The survey assessed the health of marine recreational water users in Deception Bay/Bribie Island area in northern Moreton Bay, Queensland, which is exposed to blooms of the nuisance and potentially harmful cyanobacterium Lyngbya majuscula. A postal survey was mailed to 5000 residents with a response rate of 27%. High numbers of people (78%) responding to the survey reported recreational water activity in Moreton Bay. Of those having marine recreational water activity, 34% reported at least one symptom after exposure to marine waters, with skin itching the most reported (23%). Younger participants had greater water exposure and symptoms than older participants. Participants with greater exposures were more likely to have skin and eye symptoms than less exposed groups, suggesting agents in the marine environment may have contributed to these symptoms. Of those entering Moreton Bay waters 29 (2.7%) reported severe skin symptoms, 12 of whom attended a health professional. Six (0.6%) reported the classic symptoms of recreational water exposure to L. majuscula, severe skin symptoms in the inguinal region. Participants with knowledge of L. majuscula were less likely to report less skin, gastrointestinal and fever and headache symptoms. In conclusion, high numbers of participants reported symptoms after exposure to waters subject to L. majuscula blooms but only a small number appeared to be serious in nature suggesting limited exposure to toxins.