Aim: Jellyfish known as "habu-kurage" (Chironex yamaguchii) 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 SouthEast 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 (P = 0.049), and all tourists visited the emergency department (P = 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.

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Aim: Stonefish, known in Japan as "Oni-daruma-okoze" (Synanceia verrucosa Block et Schneider), inhabit the waters surrounding the Okinawa/Amami districts. By far, habubites have been limited to these areas mainly due to climatic conditions. Due to changes promoted by global warming and increasing tourism, concerns regarding the potential for stonefish envenomation as well as jellyfish stings on the main island of Japan are increasing. However, few studies of stonefish envenomation have been reported in Japan. The current study aimed to comprehensively examine for the first time the clinical characteristics of stonefish envenomation in Japan. Methods: We administered retrospective questionnaire surveys between January 2013 and December 2017 to determine patient characteristics, treatment, and clinical outcomes of stonefish envenomation. We compared patient characteristics between tourists and non-tourists. Results: Over the 5-year study period, 15 patients were identified from four hospitals. More than 70% of stonefish envenomation cases occurred in the northern part of Okinawa Main Island. All patients recovered well, including four patients with severe stonefish envenomation. In two severe cases, the length of hospitalization was more than 1 week (8-9 days). Antivenom was not given. There were no significant differences between tourists and non-tourists with regard to baseline characteristics. Conclusions: During a 5-year period, 15 cases of stonefish envenomation occurred in Japan. The patients recovered well without treatment with antivenom.

Tripteroides bambusa bambusa (Yamada) from the Palaearctic region of Japan, and Tp. b. yaeyamensis Tanaka, Mizusawa and Saugstad from Yaeyama Islands of the Ryukyu Archipelago, Japan were elevated to the rank of full species, Tp. bambusa and Tp. yaeyamensis, respectively. The specific status was based on the demonstration of the morphological distinction, the allopatric distribution, the sterile reciprocal cross, and the DNA sequence diversity of the cytochrome c oxidase subunit I (COI).