171. Paralytic shellfish poisoning is a foodborne illness that typically develops after consumption of shellfish
contaminated chiefly with the heat stable and acid stable toxin:
(1) Okadaic acid.
(2) Mitotoxin.
(3) Saxitoxin.
(4) Aflatoxin.

Saxitoxin in Paralytic Shellfish Poisoning: Symptoms, Sources & Prevention

Paralytic Shellfish Poisoning (PSP) is a serious and potentially fatal condition caused by consuming shellfish contaminated with saxitoxin, a potent neurotoxin that remains stable even under extreme heat and acidic conditions. Unlike some foodborne toxins that degrade during cooking, saxitoxin resists breakdown, making it a persistent threat in seafood safety.

What is Saxitoxin?

Saxitoxin is a marine biotoxin produced by certain species of dinoflagellates, primarily Alexandrium, Gymnodinium, and Pyrodinium. These microorganisms can bloom in large numbers (known as harmful algal blooms or HABs), especially in warm, nutrient-rich waters. Filter-feeding shellfish like mussels, clams, oysters, and scallops accumulate saxitoxin by feeding on these toxic algae.

How Does Saxitoxin Cause Paralytic Shellfish Poisoning?

Saxitoxin works by blocking voltage-gated sodium channels in nerve cells. This interruption in nerve signal transmission leads to symptoms of neuromuscular paralysis, which can occur rapidly after ingestion.

Symptoms of PSP Include:

• Tingling and numbness around the lips and extremities

• Nausea and vomiting

• Headache and dizziness

• Muscle weakness

• In severe cases, respiratory paralysis, which may be fatal

Symptoms typically begin within 30 minutes to a few hours after consuming contaminated shellfish.

Why is Saxitoxin Particularly Dangerous?

• Heat-Stable: Cooking does not inactivate the toxin.

• Acid-Stable: It resists breakdown in the acidic environment of the stomach.

• Rapid Onset: Symptoms appear quickly, leaving little time for medical intervention if severe.

How to Prevent PSP

• Buy shellfish from certified sources: Regulatory bodies routinely monitor for toxin levels.

• Avoid shellfish during algal blooms: Red tides or harmful algal bloom warnings should be taken seriously.

• Stay informed: Public health departments often issue advisories when toxin levels rise.

Conclusion

Understanding the risks associated with saxitoxin in paralytic shellfish poisoning is crucial for seafood consumers. Since cooking cannot eliminate this toxin, prevention through awareness and regulation is the best defense. Always source shellfish from trusted, certified suppliers and stay alert to local health advisories