Rapid diarrhea, vomiting and severe stomach pain. This is how a feast can end, the basis of which will be tropical fish and seafood.
The routes by which toxins can enter the human body are mainly seafood, fish and direct contact with the algae that produce them. In most cases, the concentrations of toxins are low and do not pose a threat to human health and life. Unfortunately, when they accumulate in an organism, they are a deadly threat. The saxitoxin accumulating in crustaceans and several species of dinoflagellates (algae) and in cyanobacteria of the Aphanizomenon flos-aqua species is twice as strong as cobra venom. Its effect is to block the sodium channel, which prevents the neuorons from conducting electrical impulses, and this leads to paralysis of the muscles.
Cyanobacteria of the Anabeana species are also dangerous for us, as they secrete anatoxin-a. It also acts on neurons by disrupting the action of the neurotransmitter acetylcholine. Simplifying the problem, it can be said that the toxoid keeps the muscles contracting constantly, which can lead to death by suffocation.
These types of poisons can also be found in Polish water reservoirs, when water blooms. Bloom is a change in the color of the water to an intensely green color, which is caused by the massive growth of phytoplankton, e.g. cyanobacteria, diatoms or flowering rods. The concentration of toxins is lower than in tropical waters, but this does not protect us from poisoning. Usually it manifests itself as muscle tremors, imbalance, and in severe cases, drooling, bruising and convulsions.
Dangerous algae
Classic marine poisoning usually resembles severe food poisoning. The disease is caused by toxins called ciguatoxins. The primary source of toxins is the algae of the species Gambierdiscus toxicus, which feed on various organisms living in the sea. Poisonous algae are at the beginning of the food chain. When eaten by smaller fish, they accumulate in their bodies. When these fall prey to larger predators, toxins accumulate. The build-up of toxins in the fish’s body continues as long as the fish is alive. When caught, it usually ends up on the table and can become a lethal threat to humans.
The most common fish containing ciguatoxins in their meat are trout, salmon, mackerel, grouper, marbled perca and some moraine. Scientists have described nearly 400 species of fish living in tropical and subtropical regions, the meat of which is contaminated with toxins. But in the professional literature, cases of poisoning after eating farmed fish, such as salmon, have also been reported.
Poisoning most often occurs in the Pacific, northern Australia and the Caribbean.
Symptoms of poisoning
Usually, the first symptoms appear half an hour after eating a toxic meal. It is worth adding here that the toxins are so strong that neither high temperature nor long cooking neutralizes them.
The first symptom of poisoning is rapid diarrhea, vomiting and abdominal pain. Over time, other symptoms appear – muscle pain, dizziness, excessive sweating, anxiety states. Body temperature drops. The sick person experiences numbness of the lips and fingers. You may experience ataxia (clumsiness) and hallucinations. A very characteristic symptom of poisoning is the feeling of a strong burning sensation of the skin on contact with cold objects. In very severe cases of poisoning, the intensification of neurological symptoms leads to paralysis and death.
Symptoms of poisoning usually last for several weeks, but can also last for much longer. Sometimes, because of symptoms, poisoned people are treated as if they have been diagnosed with Multiple Sclerosis (MS).
See also: Poisoning with dishwashing detergents
There is no antidote
Unfortunately, there is no effective antidote to ciguatoxin. Only symptomatic treatment aimed at eliminating the identified disorders can be used. So far, no drug effective for this type of poisoning has been developed. With the intensification of neurological symptoms, in some cases, administration of amitryoptilin – an organic chemical compound used as a psychotropic drug has been proven. Ciguatoxin poisoning leaves a permanent mark in some people, as if it were a food impairment. It happens that in people who have been poisoned, the primary symptoms of poisoning return after eating nuts, chicken, eggs or alcohol.
According to estimated data, about 50 are sick every year due to ciguatoxin poisoning. people.
Prevention of infection with ciguatoxins comes down to avoiding eating meat from fish weighing more than 3 kilograms. Experts say that even if they contain toxins, their concentration does not pose a threat to human health.
Domoic acid
It’s a toxin found in seafood. It is very dangerous because it can damage not only the brain, but also the kidneys, even when it is lower than the limit. This thesis was confirmed by the research of scientists from South Carolina who conducted experiments on mice. In the course of their research, they proved that some of the species of algae living in the oceans produce specific chemicals that are extremely toxic to humans and other living organisms. These are neurotoxins, or poisons that damage the brain. The most dangerous and best known toxin is domoic acid. Its consumption leads to paralysis of nerve cells in the brain, in the part responsible for memory, i.e. in the hippocampus.
Poisoning occurs after eating marine molluscs that feed on phytoplankton, which produces domoic acid. Usually these are mussels, scallops and rarer species of clams. Some researchers argue that this acid can also be found in some species of fish and in diatoms.
Symptoms of poisoning are difficult to associate with the eaten meal, as amnesia, speech problems, confusion, and sometimes coma appear. Therefore, the disease is called amnestic mollusk poisoning.
Poisoning not only damages the brain, but also damages the kidneys, as the domoic acid is removed by them. It also turns out that the levels of acid that damage the kidneys are much lower than those that damage the brain.
So, if you are a mollusc foodie, you should buy them from reputable places where toxins are tested in their meat. So it is better to spend more in a good restaurant than to put yourself at great risk of health by buying mollusks in the bazaars.
Also read: Scombrotoxism – poisoning with fish from the spearfish family