Fatal ichthyosarcotoxism after eating shark meat. Implications of two new marine toxins

A fish poisoning involving 188 hospitalizations occurred in November 1993, in Manakara, a middle-sized town on the south-east coast of Madagascar, following the ingestion of shark. A single shark was involved in this poisoning and was identified as Carcharinus leucas. There was no unusual characteristic of this shark or its meat. The attack rate was about 100%. First clinical signs appeared within five to ten hours after ingestion. The patients presented neurological symptoms almost exclusively, the most prominent being a constant, severe ataxia. Gastrointestinal troubles, like diarrhoea and vomiting were rare. The overall case-fatality ratio was close to 30% among the 200 poisoned inhabitants. Search for similar poisoning previously reported in this area was negative, and fishermen in Manakara usually eat that kind of shark without mistrust. Bacteriological and chemical origins were eliminated. Two liposoluble toxins were isolated from the shark liver and tentatively named carchatoxin-A and -B respectively. They were distinct from ciguatoxin in chromatographic properties.