Seafood Toxidromes
Ciguatera Fish Poisoning
Signs and Symptoms
1. Onset 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
2. Abdominal pain, nausea, vomiting, and diarrhea usually occurring 3 to 6 hours after ingestion and possibly persisting for 48 hours
3. 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, 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
4. Tachycardia and hypertension possible
5. More severe reactions in persons previously stricken with the poisoning
6. Pathognomonic symptom: reversal of hot and cold tactile perception, which may result from generalized thermal hypersensitivity or paresthesias
7. Pruritus exacerbated by anything that increases skin temperature (blood flow), such as exercise or alcohol consumption
8. If parrot fish ingested, possible second phase, showing locomotor ataxia, dysmetria, and resting or kinetic tremor
Treatment
1. Be aware that therapy is supportive and based on symptoms.
2. 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).
3. Control hypotension with intravenous crystalloid volume replacement or oral rehydration if tolerated.
4. 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.
5. Bradyarrhythmias or excess cholinergic stimulation may respond to atropine (0.5 mg IV, up to 2 mg).
6. 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.
7. Nifedipine (begin with 10 mg PO q8h) has been used to relieve headache.
8. In the recovery phase, avoid ingestion of fish, fish sauces, shellfish, shellfish sauces, alcoholic beverages, and nuts and nut oils.
Clupeotoxin Fish Poisoning
Signs and Symptoms
1. Onset abrupt, within 30 to 60 minutes of ingestion
2. Initially, marked metallic taste, xerostomia, nausea, vomiting, diarrhea, and abdominal pain
3. Next symptoms: chills, headache, diaphoresis, severe paresthesias, muscle cramps, vertigo, malaise, tachycardia, peripheral cyanosis, and hypotension
Scombroid Fish Poisoning
Signs and Symptoms
1. Onset within 15 to 90 minutes of ingestion
2. 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
3. If untreated, resolution of symptoms generally within 8 to 12 hours
4. Reaction much more severe in a person who is concurrently ingesting isoniazid
Treatment
1. 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 histamine1 receptor antagonist and a histamine2 receptor antagonist may be more effective than either alone.
2. 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.
3. 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).
4. Treat persistent headache with acetaminophen or an antihistamine (such as cimetidine).
