Seafood Poisoning

For further information, see CMDT Part 38-54: Seafood Poisonings

Key Features

In most cases, the seafood has a normal appearance and taste
Scombroid may have a peppery taste

Clinical Findings

A variety of intoxications may occur, including scombroid, ciguatera, paralytic shellfish, and puffer fish poisoning (Table 38–8)
Abrupt respiratory arrest may occur with acute paralytic shellfish and puffer fish poisoning

Table 38–8.Common seafood poisonings.

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Table 38–8. Common seafood poisonings.

Type of Poisoning

Mechanism

Clinical Presentation

Ciguatera

Reef fish ingest toxic dinoflagellates, whose toxins accumulate in fish meat. Commonly implicated fish in the United States are barracuda, jack, snapper, and grouper.

1–6 hours after ingestion, victims develop abdominal pain, vomiting, and diarrhea accompanied by a variety of neurologic symptoms, including paresthesias, reversal of hot and cold sensation, vertigo, headache, and intense itching. Autonomic disturbances, including hypotension and bradycardia, may occur.

Scombroid

Improper preservation of large fish results in bacterial degradation of histidine to histamine. Commonly implicated fish include tuna, mahimahi, bonita, mackerel, and kingfish.

Allergic-like (anaphylactoid) symptoms are due to histamine, usually begin within 15–90 minutes, and include skin flushing, itching, urticaria, angioedema, bronchospasm, and hypotension as well as abdominal pain, vomiting, and diarrhea.

Paralytic shellfish poisoning

Dinoflagellates produce saxitoxin, which is concentrated by filter-feeding mussels and clams. Saxitoxin blocks sodium conductance and neuronal transmission in skeletal muscles.

Onset is usually within 30–60 minutes. Initial symptoms include perioral and intraoral paresthesias. Other symptoms include nausea and vomiting, headache, dizziness, dysphagia, dysarthria, ataxia, and rapidly progressive muscle weakness that may result in respiratory arrest.

Puffer fish poisoning

Tetrodotoxin is concentrated in liver, gonads, intestine, and skin. Toxic effects are similar to those of saxitoxin. Tetrodotoxin is also found in some North American newts and Central American frogs.

Onset is usually within 30–40 minutes but may be as short as 10 minutes. Initial perioral paresthesias are followed by headache, diaphoresis, nausea, vomiting, ataxia, and rapidly progressive muscle weakness that may result in respiratory arrest.

Diagnosis

Table 38–8

Treatment

Observe patients for at least 4–6 h
Replace fluid and electrolyte losses from gastroenteritis with intravenous saline or other crystalloid solution
Administer activated charcoal (50–60 mg orally) for recent ingestions
There is no specific antidote for paralytic shellfish or puffer fish poisoning
Ciguatera
- Acute neurologic symptoms may respond to mannitol, 1 g/kg intravenously (anecdotal)
Scombroid
- Antihistamines such as diphenhydramine, 25–50 mg intravenously, and the H₂-blocker cimetidine, 300 mg intravenously, are usually effective

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