Marine toxins (saxitoxin, tetrodotoxin, conotoxin)

Last reviewed: June 2019

Last updated: April 2018

Summary

Diagnosis is clinical, based on signs and symptoms, and a history of seafood or shellfish consumption, or a history of shell collection, swimming or wading in the sea, diving, or aquarium maintenance.

Confirmation is often made through the identification of the toxin in the flesh of shellfish or fish by the appropriate authorities.

Supportive care is the mainstay of treatment as there are no available effective antidotes for these toxins.

Most patients recover fully with appropriate treatment. Some will have persisting neurological symptoms for days or weeks, but can expect to fully recover after this time.

Definition

Marine toxins represent a diverse group of compounds produced by marine flora and fauna that are potentially harmful to humans. Exposure to marine toxins occurs through direct contact with or ingestion of venomous marine creatures or contaminated seafood.

This monograph covers the neurotoxins tetrodotoxin, saxitoxin, and conotoxin.

Saxitoxin is commonly ingested with contaminated shellfish.

Tetrodotoxin exposure is associated with consumption of puffer fish or direct contact with the blue-ringed octopus.

Envenomations with conotoxins occur when handling venomous marine snails.

These toxins can cause various gastrointestinal and neurological syndromes by predominantly blocking voltage-gated sodium channels in excitable cells of the heart, muscle, and neuronal tissue. Symptoms after exposure can include perioral paraesthesias, weakness, spreading numbness, and ataxia. While symptomatology depends on the specific venomous species involved, onset is generally rapid and occurs over minutes to hours. Although rare, severe intoxication can cause flaccid muscle paralysis, respiratory failure, and death. [1]

History and exam

Key diagnostic factors

presence of risk factors
oral numbness
dysphagia
dysarthria (common)
nausea (saxitoxin, tetrodotoxin)
vomiting (saxitoxin, tetrodotoxin)
diarrhoea (saxitoxin, tetrodotoxin)
weakness
ataxia/incoordination
hypertension (saxitoxin)
extreme pain (conotoxin)
hypotension or cardiovascular instability

Full details

Other diagnostic factors

light-headedness/dizziness
postural near-syncope/syncope
anxiety
loss of airway-protective reflexes
loss of adequate ventilation
hypoxia
bradycardia
apnoea
ventricular dysrhythmias

Full details

Risk factors

warmer waters
shellfish ingestion (saxitoxin)
xanthid crab ingestion (saxitoxin)
seafood ingestion (tetrodotoxin)
handling of blue-ringed octopus (tetrodotoxin)
handling of cone snail shells (conotoxin)
exposure to toxins in research/laboratory settings
bioterrorism

Full details

Diagnostic investigations

1st investigations to order

clinical diagnosis

Full details

Investigations to consider

pulse oximetry
capnography
serial pulmonary function tests
arterial blood gases
chest x-ray
CT brain
serum electrolytes
high-performance liquid chromatography in flesh of seafood

Full details

Emerging tests

serum/urine toxin analysis

Full details

Treatment algorithm

ACUTE

all patients

Contributors

Authors VIEW ALL 

William T. Hurley, MD, FACEP, FACMT

Clinical Associate Professor

Division of Emergency Medicine

University of Washington School of Medicine

Seattle

Disclosures

WTH is the author of a reference cited in this monograph.

Jacob A. Lebin, MD

Resident in Emergency Medicine

University of Washington School of Medicine

Seattle

Disclosures

JAL declares that he has no competing interests.

Arvin Akhavan, MD

Resident in Emergency Medicine

University of Washington School of Medicine

Seattle

Disclosures

AA declares that he has no competing interests.

Peer reviewers VIEW ALL 

Scott D. Phillips, MD, FACP, FACMT, FAACT

Clinical Faculty

Rocky Mountain Poison and Drug Center

Denver

Disclosures

SDP declares that he has no competing interests.

Richard S. Weisman, Pharm.D., DABAT, FAACT

Professor of Pediatrics

University of Miami

Miller School of Medicine

Director

Florida Poison Center - Miami

Miami

Disclosures

RSW declares that he has no competing interests.

Nick Buckley, MD, FRACP

Professor of Clinical Pharmacology and Toxicology

University of Sydney

Sydney

Australia

Disclosures

NB declares that he has no competing interests.

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Marine toxins (saxitoxin, tetrodotoxin, conotoxin)

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Emerging tests

Treatment algorithm

all patients

Contributors

Authors VIEW ALL 

William T. Hurley, MD, FACEP, FACMT

Disclosures

Jacob A. Lebin, MD

Disclosures

Arvin Akhavan, MD

Disclosures

Peer reviewers VIEW ALL 

Scott D. Phillips, MD, FACP, FACMT, FAACT

Disclosures

Richard S. Weisman, Pharm.D., DABAT, FAACT

Disclosures

Nick Buckley, MD, FRACP

Disclosures

Differentials

Guidelines

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