There are different types of fish poisoning, which can sometimes be fatal for the affected person. While fish poisoning caused by toxins, for example, may be very dangerous, bacterial fish poisoning is usually more harmless.
What is fish poisoning?
Schematic diagram of first aid for food poisoning and salmonella poisoning. Click to enlarge. Fish poisoning is a classic food poisoning caused by eating overcooked or infected fish. In most cases, it is a poisoning caused by bacteria from contaminated fish. In this regard, various pathogens come into consideration. However, viruses and toxins are also among the causes of risk. In some cases, fish poisoning caused by toxins is fatal. However, fish poisoning often causes only relatively harmless symptoms similar to those of a normal stomach flu.
Causes
The cause of fish poisoning is mostly due to improper storage of fish for too long. This is especially true of bacterial fish poisoning. This type of poisoning is harmless in and of itself. In addition, the fish can also be contaminated with viruses. Furthermore, special fish species cause dangerous poisoning, especially when prepared incorrectly, for example the Japanese puffer fish, which carries a toxin. The toxin is mainly found in the organs of the puffer fish. The poisoning occurs when traces of it get into the ready-to-eat muscle meat. Furthermore, the so-called ciguatera poisoning is also very feared. The trigger is a toxin that occurs in particular in fish caught in the Pacific Ocean. If the animals are infested with the toxin, then the toxin cannot be rendered harmless even by heating. Last, botulinum toxins resulting from improper storage can also be considered in fish poisoning.
Symptoms, complaints and signs
The symptoms of fish poisoning, as with food poisoning in general, depend primarily on what made the fish inedible. Fish poisoning caused by bacterial exposure from improper or overly long storage primarily causes short-term but severe gastrointestinal symptoms, such as nausea,diarrhea, abdominal pain, and vomiting. The symptoms caused by spoiled fish often appear a few hours after consumption and subside after a short time. In the case of fish poisoning caused by other toxins, various other symptoms and complaints can occur, depending on the type of toxin. These can also become dangerous in different ways. In addition to vomiting and diarrhea, other symptoms such as itching, headaches, pain in the limbs, and sensory disturbances may occur, some of which may last longer. Some symptoms may persist or recur for months after the actual poisoning. Some types of toxins can cause symptoms similar to allergic shock, such as a sudden rash or swelling and redness of the face within minutes of consumption. Other toxins, including puffer fish toxin, for example, can cause severe paralysis, resulting in potentially fatal respiratory paralysis.
Diagnosis
In most cases, the diagnosis of fish poisoning is based on a medical history. This means that one can assume to be ill with fish poisoning if unpleasant symptoms in the stomach and intestinal tract, for example diarrhea, vomiting and abdominal pain, become noticeable shortly after eating the fish meal. In most cases, this is bacterial fish poisoning. If the cause is unclear, then it is possible to examine the feces, or the remains of the consumed fish in the laboratory for potential pathogens. In addition, fish poisoning can also be caused by viruses. These are usually as “harmless” as most bacteria. In cases of high fever and general weakness, the doctor can also identify the pathogen based on a blood test. Botulinum fish poisoning can be recognized by the fact that a large number of people fall ill, especially after eating infested canned fish. Botulinum toxins can be detected in the blood and stool and are therefore an unmistakable sign of fish poisoning.
Complications
In the worst case scenario, fish poisoning can lead to death. However, whether or not serious complications occur with fish poisoning depends largely on whether it is caused by toxins or bacterial poisoning. In most cases, bacterial poisoning proceeds without major complications. In most cases, fish poisoning results in severe abdominal pain, diarrhea, vomiting and fever. These symptoms may be accompanied by nausea and fatigue, so that the patient’s daily life is severely limited. In most cases, it takes a few days to completely overcome fish poisoning. Bacterial poisoning is relatively harmless and does not require steep treatment. However, if the poisoning is caused by toxins, treatment by a doctor is necessary. In this case the body loses many minerals and vitamins and is weakened. Furthermore, fish poisoning can also negatively affect and damage the central nervous system. Treatment is either with common medications or by administering an antidote. In this case, no particular complications occur if the treatment takes place early.
When should one go to the doctor?
Fish poisoning is always a serious condition. Immediate medical treatment is required. Food poisoning from bacterially contaminated or spoiled seafood can cost victims their lives if not treated immediately. If symptoms of fish poisoning occur after eating shellfish, fish or crustaceans, seek medical attention immediately. True fish poisoning is intoxication. This should be distinguished from gastrointestinal symptoms that occur after eating fish contaminated with bacteria. Both can lead to diarrhea. However, true fish poisoning results from the spoiled parts of prepared seafood. It is therefore also far more dangerous. However, diarrhea-induced dehydration can occur with both diseases. The symptoms following the consumption of bacteria-tainted or spoiled fish dishes or mussels initially appear identical. But the toxins of real fish poisoning can wreak havoc in the body. Left untreated, they can cause visual disturbances, numbness of the limbs or fatal respiratory paralysis. Often, the symptoms of poisoning are so severe that those affected continue to suffer from secondary symptoms for weeks after the actual poisoning. People in Japan risk a special type of fish poisoning by eating puffer fish. If improperly prepared, those affected die from tetrodotoxin poisoning. This is caused by improperly removed innards of the puffer fish.
Treatment and therapy
While simple bacterial or viral fish poisoning does not require any special treatment, but usually disappears on its own after a few days, the course of fish poisoning caused by various toxins is often much more severe. Since severe diarrhea is often accompanied by a loss of water and minerals, an infusion is necessary in particularly severe cases to stabilize the fluid and electrolyte balance. For fever and pain, antipyretics such as paracetamol help. Ibuprofen is unsuitable, however, as the drug only puts more strain on the gastrointestinal tract. In the treatment of botulinum toxin fish poisoning, the doctor uses an antidote. There is no time to lose here, as such poisoning is not infrequently fatal. The treatment usually takes place in the hospital and in this respect in the intensive care unit, since the antidote is introduced into the veins. Hospitalization is also necessary for puffer fish poisoning. In ciguatera poisoning, the stomach is pumped out. The sufferer is then given an alcohol–sugar solution to stimulate urination to get the poison out of the body. Ciguatera fish poisoning can also have complications because the central nervous system is affected.
Outlook and prognosis
The prognosis for fish poisoning is highly dependent on the type of toxin that enters the body. For example, most bacterial fish poisoning is considered harmless. The symptoms usually pass on their own within a few days. This is also often the case if untreated.The situation is different, for example, with the poison of the puffer fish. The tetrodotoxin in it can kill a person, insofar as no intervention is taken. It is true that a person who is still alive 24 hours after ingestion of the poison has a very good chance of survival. The sooner medical treatment is given, the better the chances of survival. If botulinum toxins were present in the fish, the course of the disease can be particularly severe if left untreated, and is fatal in a good two-thirds of all cases. Even treated, such poisoning can still be fatal in one-tenth of cases. Ciguatera fish poisoning is treatable, but associated with mortality rates in the single digits. In addition, affected individuals may still suffer neurological symptoms here months later. In contrast, gastrointestinal and circulatory symptoms pass within a few weeks.
Prevention
Botulin toxin fish poisoning is usually caused by spoiled canned fish. Therefore, one should stay away from deformed and especially from bloated cans. Bacterial fish poisoning can be avoided by preparing only truly fresh, odorless fish. In addition, the consumption of puffer fish should be avoided as a precaution. Fish poisoning caused by ciguatera pathogens is particularly common in fish caught in the Pacific Ocean shortly after a seaquake.
Aftercare
Aftercare for fish poisoning is primarily aimed at preventing a recurrence of the typical symptoms. This is done through preventive measures. Compliance with storage standards and proper preparation of a fish are crucial. Toxins must not be allowed to enter the human bloodstream under any circumstances. After fish poisoning has been finally treated, the body does not build up immunity. Rather, the patient may become ill again and again without observing the preventive measures described. The attending physician then performs a symptom-based examination. A blood sample is taken to provide final clarity. To avoid complications, it is essential to see a doctor if you suspect you have the disease. In severe cases, there is a risk of fatal paralysis. In some cases, such as puffer fish poisoning, prolonged treatment is necessary until the patient can continue to live without symptoms. The primary goal of follow-up care is to drain the poison from the body. If other impairments have occurred, their therapy is added as an adjunct. People of advanced age are considered to be at risk. Due to their age, their organism recovers much more slowly. They are therefore followed by blood checks from time to time.
What you can do yourself
Classic fish poisoning, i.e. poisoning caused by eating fish, is typically caused by storing freshly caught fish incorrectly and for too long. In most cases, the poisoning is bacterial and usually does not require medical treatment. The most important self-help measure is to ensure electrolyte balance, because the body excretes a lot of minerals through vomiting and diarrhea, as well as through heavy sweating in the case of fever attacks, which must be replaced. A second – far more dangerous – variant of fish poisoning is poisoning by toxins that the particular fish is known to carry. Poisoning occurs when the fish has not been prepared in such a way that the toxin could not enter the part of the fish to be eaten. One species of fish that contains a highly toxic nerve toxin is the Japanese puffer fish, which requires special preparation so that the toxin is not consumed with it. If fish poisoning with botulinum toxin or another nerve toxin does occur, it is an acute emergency that requires immediate treatment in a clinic that ideally also has an antidote that can be administered intravenously. Because of the acute emergency, self-help measures or adjustments in everyday life are unnecessary. A third type of fish poisoning is known as ciguatera poisoning, which results from the consumption of normally nontoxic predatory fish under special conditions through the food chain. Again, these are acute emergencies that require immediate clinical treatment because of the threat of respiratory failure, for example.
