Paralytic shellfish poisoning (PSP) toxin- and/or tetrodotoxin-contaminated crabs and food poisoning by them

Outbreaks of human intoxication by toxic crabs have been reported in various parts of the world. Sporadic outbreaks of intoxication in humans and domestic animals due to ingestion of the toxic crab have especially occurred in the Ryukyu Islands, Japan. Using a screening test for toxic crabs, 1000 specimens of 72 species in the family Xanthidae were tested for toxicity and Zosimus aeneus, Atergatis floridus and Platypodia granulosa were found to be toxic. The toxin was confirmed to be identical to saxitoxin (STX). It was later confirmed that there are great individual and regional variations in toxicity and the toxin varies with exposure of the toxic crab to Paralytic Shellfish Poisoning (PSP) toxin and/or tetrodotoxin (TTX). Edible crabs "Togekurigani" (Telmessus acutidens) and "Ishigani" (Charybdis japonica) were contaminated with PSP for a short time in 2003, in Japan. The mechanism of PSP intoxication was shown to be the food chain by feeding PSP-contaminated bivalves. However, in the case of toxic xanthid crabs, which are not plankton feeders, the conclusions were uncertain. This review describes the occurrence, causative agents and intoxication mechanisms for food poisoning by toxic crabs containing PSP or TTX or other marine toxins, either alone or mixed.