This syndrome presents much like ciguatera poisoning but without a paralytic component and may last from several hours to a few days. The brevetoxins, unlike the other shellfish toxins, can become aerosolized by the surf and produce an allergic response characterized by rhinorrhea, conjunctivitis, bronchospasm and cough in sensitive individuals along the shore. Gastroenteritis followed by headache and short-term memory loss were seen. Severe cognitive dysfunction to the point of interfering with ability to perform normal daily activities was noted in a few cases. Seizures, coma, hemiparesis, and ophthalmoplegia were noted in the most severe cases.
Findings vary according to the syndrome involved.
Gastrointestinal symptoms occur less often in paralytic shellfish poisoning than in the other syndromes. Paresthesias of the face and extremities are only noted in paralytic and neurologic shellfish poisoning. Amnestic shellfish poisoning is the only shellfish syndrome with cognitive dysfunction as an early finding. Volume depletion from gastrointestinal symptoms is common to all syndromes. Direct human serum assays for shellfish toxins are not yet available to clinicians.