Scientists disagree as to whether the cause of the increase in ciguatera poisoning is due to an increase in the overall number of people fishing or whether the degradation of the ocean environment has caused an increase in the number of dinoflagellates. Ciguatera poisoning can increase dramatically after cyclones have damaged reefs. When larger fish eat the smaller toxic fish, the toxin becomes concentrated in the fat, muscles, and organs of the carnivorous fish. The most dangerous parts of the fish are the head and viscera where the toxin tends to concentrate. The risk to people increases as the toxin moves up the food chain into larger and larger fish.
Symptoms typically show up four to eight hours after eating a toxic fish.
The symptoms include general weakness, diarrhoea, muscle pain, joint aches, numbness around the mouth, hands and feet, and sometimes a reversal of the sensations of hot and cold. Symptoms can persist for days or weeks, but in a few cases, up to 14 months. Occasionally, as in the case of a fisherman on the Hawaiian island of Kauai, who died after eating an afflicted Marquesan sardine, ciguatera poisoning can be fatal within a few hours. Cooking does not eliminate the toxin, but rather actually concentrates it by cooking away water in the flesh of the fish. Ciguatera has been around for a long time and was reported as early as 1606 in Vanuatu, while Captain Cook described it in New Caledonia in 1774.