Q. Explain Ciguatera Fish Poisoning?

Ciguatera probably represents the most common cause of poisoning from fish in tropics. Ciguatera comprises over 50% of all reported cases of seafood poisoning. This poisoning is very common in temperate and inland areas. Ciguatera toxin, a polyether, is found in blue-green algae and protozoans and is known to affect thermoregulation and sensory, motor and muscular activities. These organisms are ingested by herbivorous fish, which, in turn, are eaten by larger fish. Ciguatera is concentrated in the flesh, adipose tissue and organs of the larger fish. Clguatera toxin is odourless and tasteless, and contaminated .fish tastes normal. What is more important, here is the fact that the toxin is heat stable and thus may affect people even if fish are prepared properly. Further, ciguatera toxin is secreted into breast milk and freely crosses the placenta, affecting the foetus. Symptoms usually are evident within 2-6 hours after ingestion and may last as long as 48 hours. It produces a spectrum of illness that is not easy to understand. Over 150 symptoms have been described, involving multiple body systems: gastrointestinal, neurological, musculoskeletal, dermatological and cardiopulmonary. Symptoms generally consist of abdominal cramps, nausea, vomiting, profuse watery diarrhoea, myalgias (pain in the muscle), arthralgias (neuralgic pain in a joint or joints), weakness and dysuria (painful or diff~cult urination).

Neurologic symptoms tend to occur later (up to 72 h) and may persist for months. These are predominantly paresthesias (a skin sensation, such as burning, prickling, itching, or tingling), but a myriad of other sometimes bizarre neurologic symptoms also may be observed, including sensation of loose painll teeth, tingling in the lips, tongue and throat, vertigo, ataxia, visual changes and seizures. Death is rare, with a reported mortality rate of approximately 1 in 1000 patients. Contrary to saxitoxin, the cigutera toxin is more potent. In fact, saxitoxin is a derivative of ciguatera toxin.