[Survey of food poisoning incidents in Japan due to ingestion of marine boxfish and their toxicity].

From 1990 to 2008, 9 food poisoning incidents due to ingestion of marine boxfish occurred in Nagasaki, Miyazaki, Mie and Kagoshima Prefectures, Japan, and a total of 13 persons were poisoned. Their main symptom was severe muscle pain arising from rhabdomyolysis, which was usually accompanied by the discharge of black urine and abnormal elevation of serum creatine phosphokinase. Twelve out of the 13 victims recovered in a few days to two months, while one died after approximately 2 weeks. Since the symptoms were very similar to those caused by parrotfish "aobudai" Scarus ovifrons poisoning, the causative substance was considered to be parrotfish toxin, i.e., a palytoxin-like substance. Epidemic surveys after the incidents in Miyazaki and Nagasaki identified the leftovers as "hakofugu" Ostracion immaculatus. During screening tests to clarify the toxicity of boxfish from Western Japan, 47 of 129 specimens (36.4%) of O. immaculatus, and 7 of 18 specimens (38.9%) of "umisuzume" Lactoria diaphana were found to show acute and/or delayed lethal activity to mice (0.5-2.0 mouse unit/g). Among the tissues tested, the frequency of toxicity was highest in the viscera excluding liver (28.6% in O. cubicus, 33.3% in L. diaphana), followed by muscle (10.9%, 5.6%) and liver (6.2%, 5.6%). From the above results, we conclude that O. cubicus and L. diaphana inhabiting the coast of Japan sometimes contain toxic substance(s), which can sporadically cause food poisonings very similar to parrotfish poisoning.