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Neurotoxic Shellfish Poisoning

Causative organism: Karenia brevis

Toxins produced: Brevetoxins


Neurotoxic Shellfish Poisoning (NSP) produces an intoxication syndrome nearly identical to that of ciguatera in which gastrointestinal and neurological symptoms predominate. In addition, formation of toxic aerosols by wave action can produce respiratory asthma-like symptoms. No deaths have been reported and the syndrome is less severe than ciguatera, but nevertheless debilitating. Unlike ciguatera, recovery is generally complete in a few days. Monitoring programs (based on Karenia brevis cell counts) generally suffice for preventing human intoxication, except when officials are caught off-guard in previously unaffected areas.

U.S. Finfish, Shellfish, and Wildlife Affected by NSP

Harmful Algal SpeciesGeographic AreaAffected Organisms*
Karenia brevisGulf of Mexico
South Atlantic Bight
Bay scallops, surf clams, oysters, southern quahogs, coquinas
Many commercial and recreational species of fish, sea birds+, sea turtles, manatees+, dolphins
*Found to contain algal toxins, or to be adversely affected by toxic or harmful marine algae.
+Causative algae implicated, not confirmed.

Medical Community

Neurotoxic Shellfish Poisoning

Additional Information on NSP including: Background, Clinical Presentation, Diagnosis, Management and Treatment, Chemical Structure, and Molecular Mechanism of Action.

Additional Resources

Neurotoxic Shellfish Poisoning
Sharon M. Watkins, Andrew Reich, Lora E. Fleming, Roberta Hammond
DOI: 10.3390/md20080021