• Monday July 13,2020

Ciguatera fish poisoning

Ciguatera fish poisoning is a passive fish poisoning that is the most common in the world. It occurs in particular by fish from the Pacific Ocean, Indian Ocean or the Caribbean.

What is Ciguatera fish poisoning?

Ciguatera fish poisoning is caused by the toxic substances maitotoxin and ciguatoxin. These are nerve poisons that enter the organism via eating fish.
© ChiccoDodiFC - stock.adobe.com

Ciguatera fish poisoning is one of the passive poisonings. This means that the poisoning symptoms are indirectly caused by the fish.

These animals contain the neurotoxins maitotoxin and ciguatoxin, which enter the animal via the food chain. The consumed fish itself is non-toxic. Only when it absorbs certain toxic substances through food can the consumer become poisoned. Therefore, the known poisoning with the muscle meat of the Japanese delicacy Fugu belongs to this type of fish poisoning.

The Ciguatera fish poisoning is thus clearly different from the active fish poisoning, which is usually caused by a sting of a poisonous fish such as the stonefish or stingrays. The symptoms of Ciguatera fish poisoning can last for many weeks, but they are not life threatening to a healthy adult.


Ciguatera fish poisoning is caused by the toxic substances maitotoxin and ciguatoxin. These are nerve poisons that enter the organism via eating fish. Being fat-soluble, they are easily absorbed by the body.

Furthermore, they are resistant to heat, so they are not destroyed by cooking and frying the fish. The fish that carries these poisons is naturally non-toxic. The reasons for its toxicity are found at the beginning of its food chain. On the coral reefs live numerous microorganisms, which are also called dinoflagellates. They contain the listed nerve agents and serve as food for the fish.

So the animals take them up and feel nothing of the poisoning themselves. The food plate unfolds the toxic effects on the human organism causing ciguatera fish poisoning.

Symptoms, complaints & signs

The symptoms and complaints of Ciguatera fish poisoning are usually very characteristic and often directly indicate the disease. The sufferers suffer primarily from a very strong sweating and continue to numbness or disorders of sensitivity. Not infrequently it also comes to a burning on the tongue or even in the entire oral cavity, so that the intake of food or liquids is no longer readily possible.

Likewise, those affected suffer from fever or chills and show dizziness. The Ciguatera fish poisoning often leads to complaints in the stomach or intestine, so many sufferers also suffer from diarrhea and nausea. If the Ciguatera fish poisoning is still not treated, it will cause cramps in the muscles and thus very severe pain.

Even the right sensation of temperatures is significantly reduced by this poisoning. In general, sufferers also suffer from a feeling of weakness and appear tired or chipped off. Ciguatera fish poisoning, however, can be treated relatively well, so it usually does not come to a reduced life expectancy. Furthermore, caffeine or alcohol may increase the symptoms of ciguatera fish poisoning.

Diagnosis & History

As with other intoxications, the proven diagnosis of Ciguatera fish poisoning is often a challenge. It can usually be diagnosed using the classic symptoms of reversal of sensation of heat and cold, nausea, and vomiting.

It is also important to record the patient's history. For this purpose, the doctor interviews the person concerned, which fish have been consumed and where the consumption took place. The responsible poison can usually be detected only with an immense effort in special laboratories.

In most cases, the disease shows a favorable course and a good prognosis. Consequential damage is not expected and the survival rate is 99%. However, the symptoms of Ciguatera fish poisoning can last for many weeks.

Ciguatoxins are among the strongest and most dangerous neurotoxins. The toxins are neither recognized by their taste, smell, or texture, nor can they be destroyed by physical processes such as heating or freezing. For mild cases of poisoning in humans, 0.1 microgram of toxin per kilogram of fish is sufficient. This alone can already be understood as a complication in avoiding such poisoning.


In light poisoning cases, it comes to a few hours after consumption first to nausea, diarrhea and vomiting. In sensitive individuals, however, the symptoms can already appear much earlier and much more violent. In addition, especially sensitive people with further complications can be expected.

For example, it often comes to a strong burning of the oral mucosa and a sharp drop in body temperature in conjunction with a nonspecific weakness. In severe poisoning, complications in the form of long-term damage are possible. In some patients, the nonspecific weakness persists for months.

In addition, those affected are physically less resilient and suffer from constant fatigue. Permanent damage to the nerves, which transmit tactile and temperature stimuli to the brain, is also possible. According to the current state of knowledge of the research, it is to be assumed that the regular consumption of alcohol and caffeine strengthens a chronic Ciguatera and strengthens the reaction of the body on renewed contact with the neurotoxin.

When should you go to the doctor?

There is no antidote for the toxins that cause ciguatera fish poisoning. Nevertheless, a doctor should be consulted promptly in case of suspected disorder, so that the concomitant symptoms of poisoning can be treated optimally and complications can be prevented.

The risk exists only after the consumption of tropical fish, whereby it does not matter otherwise with microbial impurities, whether the fish was properly cooked, because the poison is heat-resistant. Anyone who experiences symptoms such as profuse sweating, dizziness, nausea and vomiting, diarrhea, burning in the mouth or muscle spasms after eating tropical fish should seek medical attention immediately.

This is true even if initially only a slight stomach upset is observed, but suddenly the temperature sensation is disturbed. After a Ciguatera fish poisoning, there is often a reversal of the temperature sensation. For example, warm water is perceived as cold and vice versa. At the latest then a doctor should be consulted immediately.

How dangerous the poisoning is depends also on the age, the weight and the general constitution of a patient. Some people only notice a slight discomfort. If suspected ciguatera fish poisoning, a doctor should be consulted as a precaution. For severe cases, the emergency doctor may need to be called.

Treatment & Therapy

When treating Ciguatera fish poisoning, the primary aim is to alleviate the symptoms of poisoning. Since the disease is associated with frequent vomiting and diarrhea, the person should be given fluids and electrolytes.

A functioning antivenom, however, does not exist. Therefore, the causative poison can not be controlled, but it can only be a symptom treatment. Apart from the symptomatic treatment of this fish poisoning, an acute therapy is possible. As part of this treatment, the affected person receives an infusion of the sugary alcohol mannitol. This leads to a promotion of urine excretion, so that the organism excretes the poison increasingly.

If the Ciguatera fish poisoning is life-threatening, plasma expander can be administered to the patient as an infusion. These solutions increase the plasma volume of the blood. If the Ciguatera fish poisoning has only recently been in the organism, proving a pumping out of the stomach also makes sense.

Outlook & Forecast

The prognosis of Ciguatera fish poisoning is favorable. The passive fish poisoning is to be distinguished in its healing prospect of an active fish poisoning. Since not the fish in its natural way has a toxic effect on the human organism, there is normally no serious health risk for the person concerned.

Adults with a healthy immune system and no other illnesses will suffer from Ciguatera fish poisoning for a few weeks. During this time, the ingested poison is slowly transported away by the organism and excreted. Subsequently, however, the patient is considered cured and is permanently symptom-free.

Depending on the severity of the poisoning shortened or extended the healing path for the patient. Since it often comes to complaints such as fatigue, tiredness and a reduced performance, the patient must be sufficiently gentle. For optimal healing, it is important that no other pollutants are consumed. The body is busy dealing with the poisoning of the fish and should not be exposed to any further challenges.

Physical sequelae or persistent adverse effects are not documented in ciguatera fish poisoning. The survival of the person affected is not endangered despite the complaints. At best, the good prognosis can be worsened by the emergence of a mental illness such as an anxiety disorder due to the experiences.


One of the relatively common fish poisonings is the Ciguatera fish poisoning. This passive poisoning occurs preferentially on vacation by the consumption of non-toxic fish. The symptoms of intoxication were caused by toxins in the food of the fish.

As a result of ciguatera fish poisoning usually no lasting consequential damage, a follow-up is in itself obsolete. However, it is still recommended because the associated complications may last for several weeks or even months. In this respect, the Ciguatera fish poisoning is without taking a risk to life and limb.

But it should not be confused with another passive fish poisoning: the deadly poisoning of the Japanese puffer Fugu. The digestive tract symptoms are over after a few days. In certain pre-existing conditions, however, prolonged concomitant symptoms of ciguatera fish poisoning can lead to follow-up measures.

Crucial to the possible follow-up measures are factors such as the severity of Ciguatera fish poisoning and the age of the person affected. If necessary, also its pre-existing illnesses become relevant, if these are subject to a special observation.

In blood pressure patients, for example, a drop in blood pressure or weeks of rapid heart rate can lead to the need for further treatment measures. Concomitant symptoms such as persistent dizziness, muscle aches or cramps may require follow-up. The aim of the treatment is to alleviate the longer lasting after effects of Ciguatera fish poisoning. These can affect the ability to work. They reduce the well-being in severe cases over months.


Ciguatera fish poisoning can be prevented only to a limited extent, because the consumed fish themselves are not among the poisonous species or it is due to food manipulation. In addition, the poison is heat resistant, which is why cooking or roasting does not protect against poisoning. If poisoning is known to other people, fish from the contaminated area should not be consumed. It also increases the likelihood of Ciguatera fish poisoning if heavy storms or storms occur before fishing.

You can do that yourself

Since the Ciguatera fish poisoning is produced by the consumption of nontoxic fish and the causative nerve agents / neurotoxins ciguatoxin and maitotoxin can not be destroyed by heating or any other preparation method, a direct prevention is not possible, unless fish is complete deleted from the diet. However, if cases of ciguatera poisoning have become known in the region, abstinence from locally caught fish is recommended.

In addition to nonspecific symptoms such as vomiting and diarrhea, burning sensation in the mouth and numbness in the face, hands and feet except in the mouth, these specific symptoms may indicate ciguatera intoxication after a fish meal. After recognizing the symptoms, the most important self-help measure is self-initiated vomiting. If by then not all toxins have been absorbed by the digestive tract, the remainder will be eliminated by natural means and the effects of poisoning will be reduced a little.

It is important to absorb enough fluids and electrolytes during the acute period of diarrhea, which usually subsides after one to two days, to avoid secondary health problems. In order to support the excretion of toxins from the body via the kidneys, the consumption of diuretic foods or spices may be helpful and possibly shorten the duration of the longer-lasting symptoms.

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