Seafood Toxidromes

Onset is possible within 15 to 30 minutes of ingestion and generally within 1 to 3 hours; increasing severity over ensuing 4 to 6 hours; almost all victims develop symptoms by 24 hours

Abdominal pain, nausea, vomiting, and diarrhea usually occur 3 to 6 hours after ingestion and possibly persist for 48 hours

Headache, metallic taste, chills, paresthesias (particularly of the extremities and circumoral region), pruritus (particularly of the palms and soles after a delay of 2 to 5 days), tongue and throat numbness or burning, sensation of “carbonation” during swallowing, odontalgia or dental dysesthesias, sensation of loose teeth, dysphagia, dysuria, dyspnea, weakness, fatigue, tremor, fasciculations, athetosis, meningismus, aphonia, ataxia, vertigo, pain and weakness in the lower extremities, visual blurring, transient blindness, hyporeflexia, seizures, nasal congestion and dryness, conjunctivitis, maculopapular rash, skin vesiculations, dermatographia, sialorrhea, diaphoresis, arthralgias, myalgias (particularly in the lower back and thighs), painful ejaculation with urethritis, insomnia, bradycardia, hypotension, central respiratory failure, and coma

Tachycardia and hypertension are possible

More severe reactions in persons previously stricken with the poisoning

Pathognomonic symptom: reversal of hot and cold tactile perception, which may result from generalized thermal hypersensitivity or paresthesias

Pruritus exacerbated by anything that increases skin temperature (blood flow), such as exercise or alcohol consumption

If parrotfish ingested, possible second phase, showing locomotor ataxia, dysmetria, and resting or kinetic tremor

Be aware that therapy is supportive and based on symptoms.

Control nausea and vomiting with an antiemetic (prochlorperazine, 2.5 mg IV; ondansetron, 4 mg IV or PO dissolving tablet; or promethazine, 25 mg IM).

Control hypotension with intravenous crystalloid volume replacement or oral rehydration if tolerated.

For arrhythmias, heart block, hypotension, or severe neurologic symptoms, administer mannitol (20% solution), 1 g/kg IV over 45 to 60 minutes during the acute phase (days 1 to 5). This therapy is not consistently proven to be beneficial.

Bradyarrhythmias or excess cholinergic stimulation may respond to atropine (0.5 mg IV, up to 2 mg).

For pruritus, administer hydroxyzine, 25 mg PO q6–8h. Cool showers may help. Amitriptyline, 25 mg PO q12h, may relieve pruritus and dysesthesias, as well as emotional depression.

Nifedipine (begin with 10 mg PO q8h) has been used to relieve headache.

In the recovery phase, avoid ingestion of fish, fish sauces, shellfish, shellfish sauces, alcoholic beverages, and nuts and nut oils.

Onset is abrupt, within 30 to 60 minutes of ingestion

Initially, marked metallic taste, xerostomia, nausea, vomiting, diarrhea, and abdominal pain

Next symptoms: chills, headache, diaphoresis, severe paresthesias, muscle cramps, vertigo, malaise, tachycardia, peripheral cyanosis, and hypotension

Death can occur within 15 minutes of onset of symptoms

Therapy is supportive and based on symptoms.

Because of the severe nature of the intoxication, early gastric emptying is desirable. However, the affliction is so unusual that the victim may die before the diagnosis is suspected.

Onset within 15 to 90 minutes of ingestion

Flushing (sharply demarcated, exacerbated by ultraviolet exposure, particularly of the face, neck, and upper trunk), sensation of warmth without elevated core temperature, conjunctival hyperemia, pruritus, urticaria, angioneurotic edema, bronchospasm, nausea, vomiting, diarrhea, epigastric pain, abdominal cramps, dysphagia, headache, thirst, pharyngitis, burning of the gingivae, palpitations, tachycardia, dizziness, hypotension, localized numbness of the oropharynx, and rare arrhythmias

If untreated, resolution of symptoms generally within 8 to 12 hours

Reaction much more severe in a person who is concurrently ingesting isoniazid

Administer an antihistamine (diphenhydramine, 25 to 50 mg PO or IV; cimetidine, 300 mg, or ranitidine, 50 mg IV). Alternatives are nizatidine, 150 mg PO, or famotidine, 20 mg PO. Combination therapy with both a histamine ₁ receptor antagonist and a histamine ₂ receptor antagonist may be more effective than either alone.

If the patient is severely ill with facial swelling indicative of an airway obstruction, hypotension, or significant bronchospasm, treat as for an allergic reaction with epinephrine and inhaled bronchodilators in addition to antihistamines (see Chapter 26 ). Corticosteroids are of no proven benefit for scombroid in the absence of anaphylaxis.

Control nausea and vomiting that do not remit after antihistamine administration with an antiemetic (prochlorperazine, 2.5 mg IV; promethazine, 25 mg IM; or ondansetron 4 mg IV or PO dissolving tablet).

Treat persistent headache with acetaminophen or an antihistamine (such as cimetidine).

Make sure that all captured fish are gutted, cooled, and refrigerated or placed on ice or frozen immediately.

Do not consume fish that has been handled improperly or carries the odor of ammonia. Fresh fish generally has a sheen or oily rainbow appearance; avoid “dull” fish or those that do not smell fresh.

Onset possibly as rapid as 10 minutes or delayed for up to 4 hours; usually occurs within 30 minutes of ingestion; death may occur within 20 minutes

Initial symptoms: oral (lips and tongue) paresthesias, lightheadedness, and then general paresthesias

Rapidly developing symptoms: hypersalivation, diaphoresis, lethargy, headache, nausea, vomiting, diarrhea, abdominal pain, weakness, ataxia, incoordination, tremor, paralysis, cyanosis, aphonia, dysphagia, seizures, bradycardia, dyspnea, bronchorrhea, bronchospasm, respiratory failure, coma, hypotension, and coagulopathy

Gastrointestinal symptoms may be severe and include nausea, vomiting, diarrhea, and abdominal pain

Miosis progressing to mydriasis with poor papillary light reflex

When mechanical ventilation maintained and no anoxic brain injury present, full mentation maintained with total flaccid paralysis

Be aware that the toxin is stable in gastric acid and partially inactivated in alkaline solutions.

Secure the airway, and administer oxygen.

Perform gastric lavage with 2 L of 2% sodium bicarbonate in 200-mL aliquots, followed by placement of 50 to 100 g of activated charcoal in 70% sorbitol solution (or 30 g of “highly activated” charcoal in sorbitol).

Further therapy is supportive and based on symptoms. Atropine may be used to treat bradycardia. Pressors that are α-agonists, such as phenylephrine or norepinephrine, may be effective to treat hypotension, taking care to first ensure adequate fluid resuscitation. Cholinesterase inhibitors, such as edrophonium and neostigmine, have met with varying success.

Within minutes (usually 30 to 60) to a few hours after ingestion of contaminated shellfish, onset of intraoral and perioral paresthesias, notably of the lips, tongue, and gums, which progress rapidly to involve the neck and distal extremities; early onset of vertigo

Tingling or burning sensation that becomes numbness

Gastroenteritis in only 25% of victims

Light-headedness, sensation of “floating,” disequilibrium, incoordination, weakness, hyperreflexia, incoherence, dysarthria, sialorrhea, dysphagia, dysphonia, thirst, diarrhea, abdominal pain, nausea, vomiting, nystagmus, dysmetria, headache, diaphoresis, loss of vision, sensation of loose teeth, chest pain, and tachycardia

Flaccid paralysis and respiratory insufficiency 2 to 12 hours after ingestion

Unless there is a period of anoxia, the patient is often awake and alert, although paralyzed