II. Pathophysiology

  1. Consumption of shellfish (mussels, clams) containing Domoic Acid
  2. Effects are seen in humans as well as marine animals including birds

III. Mechanism

  1. Domoic Acid is produced by Pseudo-Nitzschia Diatoms (marine algae)
  2. Shellfish that filter feed (e.g. mussels, clams) accumulate the Domoic Acid toxin
  3. Domoic Acid is a non-protein Amino Acid
    1. Tasteless and odorless
    2. Heat stable
    3. Water soluble
  4. Domoic Acid is a Neurotoxin
    1. Excitatory at glutamate receptors
    2. Results in large influx of Calcium and Sodium, causing Neuronal cell death

IV. Findings

  1. Domoic Acid onset of activity within 5 hours of ingestion
  2. Gastrointestinal
    1. Abdominal Pain and cramping
    2. Nausea or Vomiting
    3. Diarrhea
  3. Neurologic
    1. Confusion and Disorientation to coma
    2. Memory Loss
    3. Hemiparesis
    4. Cranial Nerve palsy (e.g. Ophthalmoplegia)
    5. Purposeless chewing or grimacing
    6. Seizures or Status Epilepticus
  4. Cardiovascular
    1. Cardiac Dysrhythmia
    2. Hemodynamic instability

V. Evaluation

  1. See Unknown Ingestion
  2. See Altered Level of Consciousness
  3. Bedside Glucose
  4. Comprehensive metabolic panel
  5. Toxicology Screening
  6. Electrocardiogram
  7. CT Head
  8. Leftover Shellfish can be tested for toxins (ELISA, Liquid chromatography)

VI. Management

  1. Consider alternative diagnoses (see evaluation above)
  2. Supportive Care
    1. Intravenous Fluids
    2. Antiemetics
    3. Status Epilepticus management
    4. Vasopressors for refractory Hypotension
  3. Disposition
    1. Observe all patients with unclear cause, neurologic deficit, cardiovascular instability or Electrolyte abnormality
    2. Patients with mild symptoms may be discharged with close interval follow-up

VII. Complications

  1. Death (2%)
    1. Mortality is primarily in elderly
  2. Seizures
    1. Resolve over weeks in most cases
  3. Persistent Neurologic Deficits (<10%)

IX. References

  1. Koch and Tomaszewski (2018) Crit Dec Emerg Med 32(5): 32
  2. Jeffery (2004) Food Chem Toxicol 42(4):545-57 +PMID:15019178 [PubMed]

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Related Studies

Ontology: domoic acid (C0058678)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C012301
SnomedCT 67938008
English 3-pyrrolidineacetic acid, 2-carboxy-4-(5-carboxy-1-methyl-1,3-hexadienyl)-, (2S-(2 alpha,3 beta,4 beta(1E,3E,5R*)))-, domoic acid, Amnesiac shellfish poison, amnesic shellfish poison, Amnesic shellfish poisoning, Amnesic shellfish poison, Domoic acid, Amnesic shellfish poison (substance), Demoic acid
Spanish veneno amnésico de los mariscos (sustancia), veneno amnésico de los mariscos, veneno amnésico de los moluscos, ácido domóico

Ontology: Amnesic Shellfish Poisoning (C0521825)

Definition (MSH) A condition caused by ingestion of shellfish contaminated by domoic acid-producing diatoms of the genus Pseudo-nitzschia.
Concepts Injury or Poisoning (T037)
MSH D057096
SnomedCT 95878009
English Shellfish Poisoning, Amnesic, Amnesic Shellfish Poisonings, Shellfish Poisonings, Amnesic, Amnesic Shellfish Poisoning, Poisoning, Amnesic Shellfish, Poisonings, Amnesic Shellfish, Amnesic shellfish poisoning, Amnesic shellfish poisoning (disorder)
French IAC (Intoxication Amnésique par Coquillages), IAFM, Intoxication amnésique par coquillages, Intoxication amnésiante par coquillages, Intoxication amnésique par fruits de mer, Intoxication amnésiante par fruits de mer
German Amnestische Schalentiervergiftung
Czech měkkýši, korýši - amnestická otrava
Italian Avvelenamento amnesico da molluschi
Norwegian ASP–skalldyrforgiftninger
Spanish intoxicación amnésica por mariscos (trastorno), intoxicación amnésica por mariscos