Seafood poisoning can result from the ingestion of seafood that contains toxic substances. Often, these toxins originate from dinoflagellates. Dinoflagellates, which form the major component of phytoplankton, are unicellular eukaryotic marine algae of the division Pyrrophyta. Other toxins are endogenously produced or result from bacterial action.
Ciguatera, paralytic shellfish, tetrodotoxin, and scombroid poisoning are relatively well known. Neurotoxic shellfish, diarrheic shellfish, hallucinatory fish, clupeotoxic fish, fish roe, palytoxin, domoic acid (mussel) and red whelk poisoning, and Haff disease are less commonly recognized and reported. However, expanding international tourism, the importation of exotic seafood, and the harvesting of seafood from more remote waters, as coastal fishing grounds are exhausted, are likely to increase the frequency of seafood poisoning seen in domestic health facilities.
|Spectrum of Seafood poisoning||Source of Human Exposure|
|Ciguatera poisoning||Reef fish > 2 kg|
|Ciguatera-like poisoning Palytoxin Neurotoxic shellfish poisoning||Reef fish Clams and oysters|
|Paralytic shellfish poisoning||Clams, mussels, scallops, cockles and oysters|
|Tetrodotoxin||Puffer fish, blue-ringed octopus|
|Scombroid poisoning||Mackerel, skipjack and tuna|
|Diarrhoeic shellfish poisoning||Mussels|
|Hallucinatory fish poisoning||Reef fish|
|Domoic acid poisoning||Mussels|
|Raw carp bile poisoning||Carp > 3 kg|
The clinical presentation of ciguatera, neurotoxic shellfish, palytoxin, tetrodotoxin, and paralytic shellfish poisoning may be difficult to distinguish, as all may involve symptoms of paresthesias, weakness, and ataxia. Predominant symptoms and the nature of the fish eaten are used to determine the specific etiology.
The differential diagnosis of toxic seafood poisoning includes infectious gastroenteritis. Common seafood pathogens are hepatitis A, Norwalk virus, Vibrio spp. (V. cholerae, V. parahaemolyticus, and V. vulnificus), Clostridium botulinum, Escherichia coli, Giardia lamblia, and species of Campylobacter, Shigella, and Salmonella.
Scombroid poisoning can usually be differentiated from true allergic or anaphylactic reactions by the history of fish ingestion.The differential diagnosis of skin flushing also includes poisoning by niacin, vancomycin, rifampin, monosodium glutamate, and ethanol or disulfiram reactions.