Neurotoxic shellfish poisoning (NSP) is caused by the consumption of shellfish contaminated by breve-toxins or brevetoxin analogs.
Symptoms in humans include vomiting and nausea and a variety of neurological symptoms such as slurred speech. No fatalities have been reported but there are a number of cases which led to hospitalization.
References
Neurotoxic shellfish poisoning Wikipedia(Text) CC BY-SA