Clinical characteristics of jellyfish stings in Japan.

Aim: Jellyfish known as "habu-kurage" () inhabit the waters surrounding Okinawa and Amami, Japan, and jellyfish stings are limited to areas outside the Japanese main island. However, the shifts promoted by global warming and increasingly intensive interactions with people have led to concerns regarding the possibility of increased jellyfish stings on the main island of Japan. Similar concerns are being raised all over the world. However, studies examining clinical characteristics of jellyfish stings have been limited to Australia, the USA, Europe, and South-East Asia. Thus, this study aimed to examine for the first time the clinical characteristics of jellyfish stings in Japan.

Methods: We undertook retrospective questionnaire surveys from January 2013 to December 2017 to determine patient characteristics, treatment, and clinical outcomes. We compared patient characteristics between tourists and non-tourists. The primary end-point of the present study was to clarify the clinical characteristics of jellyfish stings.

Results: Over the 5-year study period, 204 patients were identified from eight hospitals based on the basic questionnaire, and 35 patients with moderate-to-severe jellyfish stings were also identified. All patients recovered well, including five patients with severe jellyfish stings. Antivenom was not given. The time intervals from the occurrence of jellyfish stings to hospital arrival significantly differed between tourists and non-tourists ( = 0.049), and all tourists visited the emergency department ( = 0.009).

Conclusions: Approximately 40 cases of jellyfish stings occurred annually in Japan between 2013 and 2017. Patients recovered well without the use of antivenom.