‘The naturally occurring chemicals secreted by certain species of bacteria or algae which are concentrated in the contaminated sea food usually shellfish, fish and crustaceans i.e.: lobster and crabs and cause serious human illness are called marine or seafood toxins.’
The food containing these toxins looks, taste and smell normal but when humans use this food as diet then it leads to certain diseases. There is no known antidote for these toxins hence supportive care is the only treatment. These are not affected by heating and cooking that is they are heat stable. These toxins produce gastrointestinal, neurological and cardiovascular syndromes. Intoxication from sea food rarely occurs due to the production of histamine by the presence of spoilage bacteria in the scombroid fish.
All around the world the cases of sea food poisoning increases with the passage of time, as it depends on the symptoms created and particular poison or pathogen causing it. Poisoning from phycotoxins, tetrodotoxins and histamine comprise the majority of these cases. As the smaller fish containing these toxins that feed on algae are eaten up by the other fishes then accumulation to the higher level occurs in larger fishes at the extreme top of the food chain. To reduce the probable health risks one must purchase the food from reliable source, handle and store it properly and follow the precautionary measures while eating seafood.
Illness related to marine toxins:
Due to the toxic nature of chemicals in seafood the different kinds of marine toxins produce different symptoms regarding specific illness. The symptoms usually appear within half an hour of eating the contaminated fish. Description of some illness are given below:
Scombrotoxic fish poisoning:
It is also called as scombroid or histamine fish poisoning. It is an illness caused by histamine, a toxin secreted by the bacterial spoilage of finfish which are not accurately refrigerated and stored. When the bacteria alter the proteins into simpler substances then the byproducts histamine and other chemicals that obstruct the protein conversion into simpler substances accumulate in the fish. Eating such contaminated fish cause scombroid. The symptoms include diarrhea, vomiting, sweating, headache, appearance of rashes on body, inflammation of mouth and abdominal pain. Antihistamines and epinephrine may also be used in specific circumstances.
Ciguatera fish poisoning:
It is an illness occurred after consuming the reef fish infected with ciguatoxin or maitotoxin. These persuasive toxins are derived by dianoflagellates that grow on corals and eaten up by the herbivorous fish and from where the toxins concentrate as the pass up the food chain from carnivorous fish thus finally reaching the humans. The toxins usually accumulate in the intestine, head and liver of fish. Eating such contaminated fish causes illness. The symptoms include diarrhea, fatigue, itching, dizziness, burning sensations and problem of alteration of temperature sensation.
Paralytic shellfish poisoning:
It is a serious illness caused by eating shellfish containing biotoxin secreted by algae. As shellfishes are filter feeders so when then they pump water, intake of food particles and algae occurs which hen accumulate in their tissues. When these are eaten by humans it leads to illness. Their toxicity is high than cyanide that it can lead to death. The symptoms include headache, dizziness, muscular in coordination, difficulty in breathing and paralysis, as the toxin directly affects the nervous system.
Neurotoxin shellfish poisoning
It is an illness caused by eating shellfish containing brevetoxins, a neurotoxin secreted by dinoflagellate, Gymnodinium breve. Inhalation of this toxin provokes bronchoconstriction thus leading to problems of respiration. The symptoms include nausea, vomiting, reversal of temperature sensation, loss of coordination, limb paralysis, and muscle fatigue. Its neurological symptoms resemble acute ciguatera poisoning. The asthma patients may experience severe effects.
Diarrhetic shellfish poisoning:
It is an acute gastrointestinal illness caused by eating bivalve mollusk having okadoic acid, biotoxin, secreted by Dinophysis through filter feeders. The symptoms include nausea, vomiting, fever, cold, stomach pain and headache.
Amnesic shellfish poisoning:
It is an infrequent condition caused by consuming shellfish, bivalve mollusks having algal toxin, Domoic acid, a toxin secreted by diatoms that affect the nervous system. These toxins are accumulated in fish tissues and when eaten case illness. It can sometimes lead to short term memory loss. The symptoms include upset of gastrointestinal track, headache, dizziness, and seizures and at the extreme level paralysis, comma and death occurred.
Puffer fish poisoning:
It is a lethal intoxication caused by eating puffer fish containing tetrodotoxin secreted by bacteria accumulated in liver, spleen and skin of fish. The responsible pathogen, tetrodotoxin, is not affected by heat and dissolves in water thus obstruct nerve transmission in skeletal muscles. Te symptoms include dizziness, vomiting, sensation such as floating and sometimes paralysis.