PARALYTIC SHELLFISH POISONING

• This derives from dinoflagellates contaminating shellfish (clams, scallops, oysters, etc.). The toxin, saxotoxin, is water soluble, heat and base stabile, and is therefore not affected by steaming or cooking. It inhibits sodium channels of excitable membranes, blocking propagation of nerve and muscle action potentials.
• Symptoms: These usually occur within 30 minutes, and include parasthesias of the lips, tongue, gums and face. This process proceeds to the trunk and may progress to paralysis and respiratory arrest. The gastrointestinal form may appear hours or days after ingestion with nausea, vomiting, diarrhea and abdominal pain.
• Treatment: No specific treatment. Stop eating if oral sensations are perceived. Empty stomach if systemic symptoms are noted, using emetic or lavage. Give respiratory support and monitoring if needed.

SCOMBROID

• Occurs in tuna, mackerel, skipjack and other members of the family scombridae. Fish left at room temperature undergo bacterial breakdown of tissue histidine to histamine and saurine. Spoiled fish have a sharp, peppery taste.
• Symptoms: Occur in the first hour, and a histamine-like intoxication is seen. There is headache, flushing, dizziness, palpitations and tachycardia. One may see hypotension, bronchospasm, urticaria and anaphylaxis. GI symptoms include nausea, vomiting, diarrhea, abdominal pain, thirst and dysphagia.
• Treatment: Gastric lavage, respiratory and circulatory support. Antihistamines appear to be helpful.

TETRADOTOXIN (Puffer fish)

• Derived from algae covered with bacteria Alteromonas sp.Being ingested by pufferfish. The toxin concentrates in the liver and gonads. The toxin inhibits sodium transport, affects neuronal transmission in the CNS and periphery and also affects cardiac nerve conduction and contraction.
• Symptoms: Entirely dose dependent-can have oral paresthesias, muscular fasciculations then a flaccid type of paralysis occurs. (curare-like).
• Treatment: Gastric lavage and respiratory support, usually for 24 hours or more. Consider sedation because cognitive function intact. There will be spontaneous remission if the patient is otherwise supported.

CIGUATERA

• The toxin, icthyosarcotoxin, is heat stable, lipid soluble and comes from the dinoflagellate Gambierdiscus toxicus. It is common in the tropics, concentrated up the food chain and is seen in eels, red snapper, amberjack and so forth.
• Symptoms: vary, the usual onset occurs in the first 12 hours and can last for ten to twelve days. The GI symptoms are followed by myalgias, arthralgias and paresthesias. There is the heat/cold reversal phenomenon and this is supposed to be diagnostic. Neurological symptoms may take months to resolve and occasionally may be permanent. Symptoms are aggravated by alcohol and by eating a fish only slightly affected.
• Treatment: nonspecific, primarily supportive. Suggested treatment has included calcium gluconate, corticosteroids, atropine, vitamin B, pyroxidine, amitriptyline and mannitol. Mannitol treatment is 250 cc 20% Mannitol (1mg/kg), this usually relieves the neurological symptoms in minutes and the rest of the symptoms in 3 days.