Fish neurotoxin: Ciguatera Fish Poisoning: Treatment, Prevention and Management

20.08.202319.07.2023 by alexxlab

Fish Poisoning | Johns Hopkins Medicine

At certain times of the year, various species of fish and shellfish contain poisonous biotoxins, even if well cooked. According to the CDC, it is considered an under-recognized risk for travelers, specifically in the tropics and subtropics.

Certain fish—groupers, barracudas, moray eel, sturgeon, sea bass, red snapper, amberjack, mackerel, parrot fish, surgeonfish, and triggerfish—can cause ciguatera fish poisoning. The CDC recommends never eating moray eel or barracuda. Other types of fish that may contain the toxin at unpredictable times include sea bass and a wide range of tropical reef and warm-water fish. Fish containing these toxins do not look, smell, or taste bad. Cooking, marinating, freezing, or stewing does not destroy the toxin.

The risk of ciguatera poisoning exists in all tropical and subtropical waters of the West Indies, the Pacific Ocean, and the Indian Ocean, where these reef fish are eaten.

Two other forms of poisoning can happen from naturally occurring toxins in fish: tetrodotoxin, sometimes called pufferfish poisoning or fugu poisoning, and scombroid poisoning.

Where is the risk of ciguatera poisoning the greatest?

Reef fish from the tropical and subtropical waters of the West Indies, the Pacific Ocean, and the Indian Ocean pose the greatest threat. Cases have been reported in the United States in Hawaii, Guam, Puerto Rico, U.S. Virgin Islands, and Florida. A few isolated cases of ciguatera poisoning have even been noted along the eastern seaboard of the United States.

More than 400 species of fish, particularly reef fish, are thought to contain the toxin for ciguatera poisoning.

What are the symptoms of ciguatera poisoning?

Symptoms of ciguatera poisoning generally appear between a few minutes and 6 hours after the toxic fish has been eaten. These include a variety of gastrointestinal, neurological, and cardiovascular abnormalities. The following are the most common symptoms of ciguatera poisoning. However, each individual may experience symptoms differently. Symptoms may include:

In more severe cases, the person may suffer muscle pains, dizziness, and sensations of temperature reversal, where hot things seem cold and cold things seem hot. Irregular heart rhythms and low blood pressure may also be experienced. Ciguatera poisoning symptoms typically resolve within several days, but may last up to 4 weeks. The symptoms of ciguatera poisoning may resemble other medical conditions. Always talk with your healthcare provider for a diagnosis.

Treatment for ciguatera poisoning

Treatment for ciguatera poisoning involves relieving the symptoms and treating any complications. There is no specific antidote for the toxin itself. Generally, recovery takes from several days to several weeks.

What is tetrodotoxin?

Tetrodotoxin, also called pufferfish poisoning or fugu poisoning, is a much rarer form of fish poisoning. Yet, it is potentially very serious. This is almost exclusively associated with eating the pufferfish from waters of the Indo-Pacific regions. There have also been several reported cases of poisonings, including fatalities, from pufferfish from the Atlantic Ocean, Gulf of Mexico, and Gulf of California. Pufferfish poisoning is a continuing problem in Japan.

What are the symptoms of pufferfish poisoning?

Symptoms generally appear between 20 minutes and 3 hours after eating the poisonous pufferfish. The following are the most common symptoms of pufferfish poisoning. However, each individual may experience symptoms differently. Symptoms may include:

Numbness of lips and tongue
Numbness of face and extremities
Sensations of lightness or floating
Headache
Nausea and vomiting
Abdominal pain
Diarrhea
Slurred speech
Difficulty walking
Extensive muscle weakness
Convulsions
Respiratory distress
Mental impairment
Cardiac arrhythmia

Death can happen within 4 to 6 hours of poisoning. It is essential to seek immediate medical attention.

Treatment for pufferfish poisoning

Treatment for pufferfish poisoning consists of limiting the body’s absorption of the toxin, relieving symptoms, and treating life-threatening complications. There is no known antidote for tetrodotoxin.

What is scombrotoxin?

Scombrotoxin, also called scombroid poisoning or histamine poisoning, happens after eating fish that contain high levels of histamine due to improper food handling. It remains one of the most common forms of fish poisoning in the U.S. and worldwide. These fish, which include mahi mahi (dolphin fish), albacore tuna, bluefin and yellowfin tuna, bluefish, mackerel, sardines, anchovy, herring, marlin, amberjack, and abalone, have high amounts of histidine. As a result of inadequate refrigeration or preservation, bacteria convert the histidine to histamine. This leads to scombroid poisoning. Contaminated fish may appear and taste fresh, although some may taste “peppery,” “spicy,” or “bubbly. ” The toxin may form even if the fish has only been temporarily stored at too high a temperature.

This form of fish poisoning happens worldwide in temperate and tropical waters.

What are the symptoms of scombroid poisoning?

Symptoms generally appear within minutes to an hour after eating affected fish. They typically last 3 hours, but can last several days. The following are the most common symptoms of scombroid poisoning. However, each individual may experience symptoms differently. Symptoms may include:

Tingling or burning sensations in the mouth
Rash on the face and upper body
Wheezing or shortness of breath
Drop in blood pressure
Throbbing headache
Hives and itching of skin
Nausea
Vomiting
Diarrhea

The symptoms of scombroid poisoning may resemble other medical conditions. Many cases of “fish allergy” are actually scombroid poisoning. Always talk with your healthcare provider for a diagnosis.

Treatment for scombroid poisoning

Treatment for scombroid poisoning is generally unnecessary. Symptoms usually resolve within 12 hours and scombroid poisoning is rarely life-threatening. Treatment could include antihistamines, such as diphenhydramine and cimetidine.

Specific treatment for all fish and shellfish poisoning is based on:

Your overall health and medical history
Extent of the disease
Your tolerance for specific medicines, procedures, and therapies
Your opinion or preference

Poisoning – fish and shellfish Information | Mount Sinai

Fish poisoning; Dinoflagellate poisoning; Seafood contamination; Paralytic shellfish poisoning; Ciguatera poisoning

This article describes a group of different conditions caused by eating contaminated fish and seafood. The most common of these are ciguatera poisoning, scombroid poisoning, and various shellfish poisonings.

This article is for information only. DO NOT use it to treat or manage an actual poison exposure. If you or someone you are with has an exposure, call the local emergency number (such as 911), or the local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.

Poisonous Ingredient

In ciguatera poisoning, the poisonous ingredient is ciguatoxin. This is a poison made in small amounts by certain algae and algae-like organisms called dinoflagellates. Small fish that eat the algae become contaminated. If larger fish eat a lot of the smaller, contaminated fish, the poison can build up to a dangerous level, which can make you sick if you eat the fish. Ciguatoxin is “heat-stable.” That means it does not matter how well you cook your fish, if the fish is contaminated, you will become poisoned.

In scombroid poisoning, the poisonous ingredient is a combination of histamine and similar substances. After the fish dies, bacteria create large amounts of the toxin if the fish is not immediately refrigerated or frozen.

In shellfish poisoning, the poisonous ingredients are toxins made by algae-like organisms called dinoflagellates, which build up in some types of shellfish. There are many different types of shellfish poisoning. The most well-known types are paralytic shellfish poisoning, neurotoxic shellfish poisoning, and amnesic shellfish poisoning.

Where Found

Ciguatera poisoning normally occurs in larger fish from warm tropical waters. The most popular types of these fish used for food include sea bass, grouper, and red snapper. In the United States, the waters around Florida and Hawaii are most likely to have contaminated fish. Worldwide, ciguatera fish poisoning is the most common type of poisoning from marine biotoxins. It is a major public health problem in the Caribbean.

The risk is greatest in the summer months, or any time a large number of algae are blooming in the ocean, such as during “red tide.” A red tide occurs when there is a rapid increase in the amount of dinoflagellates in the water. However, thanks to modern transportation, anyone around the world may eat a fish from contaminated waters.

Scombroid poisoning most often occurs from large, dark meat fish such as tuna, mackerel, mahi mahi, and albacore. Because this poison develops after a fish is caught and dies, it does not matter where the fish is caught. The main factor is how long the fish sits out before being refrigerated or frozen.

Like ciguatera poisoning, most shellfish poisonings occur in warmer waters. However, poisonings have occurred as far north as Alaska and are common in New England. Most shellfish poisonings occur during the summer months. You may have heard the saying “Never eat seafood in months that do not have the letter R.” This includes May through August. Shellfish poisoning occurs in seafood with two shells, such as clams, oysters, mussels, and sometimes scallops.

Always check with your local health department or fish and wildlife agency if you have any questions about the safety of eating any food product.

Symptoms

The harmful substances that cause ciguatera, scombroid, and shellfish poisonings are heat stable, so no amount of cooking will prevent you from becoming poisoned if you eat contaminated fish. Symptoms depend on the specific type of poisoning.

Ciguatera poisoning symptoms can occur 2 to 12 hours after eating the fish. They include:

Abdominal cramps
Diarrhea (severe and watery)
Nausea and vomiting

Shortly after these symptoms develop, you will start to have strange sensations, which may include:

A feeling that your teeth are loose and about to fall out
Confusing hot and cold temperatures (for instance, you will feel like an ice cube is burning you, while a match is freezing your skin)
Headache (probably the most common symptom)
Low heart rate and low blood pressure (in very severe cases)
Metallic taste in the mouth

These symptoms may get worse if you drink alcohol with your meal.

Scombroid poisoning symptoms most often occur immediately after eating the fish. They may include:

Breathing problems, including wheezing and chest tightness (in severe cases)
Extremely red skin on the face and body
Flushing
Hives and itching
Nausea and vomiting
Peppery or bitter taste

Below are other well-known types of seafood poisoning, and their symptoms.

Paralytic shellfish poisoning: About 30 minutes after eating contaminated seafood, you may have numbness or tingling in your mouth. This sensation may spread down to your arms and legs. You may become very dizzy, have a headache, and, in some cases, your arms and legs may become temporarily paralyzed. Some people may also have nausea, vomiting, and diarrhea, although these symptoms are much less common.

Neurotoxic shellfish poisoning: The symptoms are very similar to those of ciguatera poisoning. After eating contaminated clams or mussels, you may experience nausea, vomiting, and diarrhea. These symptoms will be followed soon after by strange sensations that may include numbness or tingling in your mouth, headache, dizziness, and hot and cold temperature reversal.

Amnesic shellfish poisoning: This is a strange and rare form of poisoning that begins with nausea, vomiting, and diarrhea. These symptoms are followed by short-term memory loss, and other less common nervous system symptoms.

Home Care

Shellfish poisoning may be a medical emergency. A person with serious or sudden symptoms should immediately be taken to an emergency medical center right away. You may need to call the local emergency number (such as 911) or poison control for appropriate treatment information.

Before Calling Emergency

The following information is helpful for emergency assistance:

Person’s age, weight, and condition
Type of fish eaten
Time it was eaten
Amount swallowed

However, DO NOT delay calling for help if this information is not immediately available.

Poison Control

Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.

This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.

What to Expect at the Emergency Room

If you have ciguatera poisoning, you may receive:

Blood and urine tests
ECG (electrocardiogram, or heart tracing)
Fluids by IV (through a vein)
Medicines to stop vomiting
Medicines to help reduce nervous system symptoms (mannitol)

If you have scombroid poisoning, you may receive:

Airway support, including oxygen, breathing tube through the mouth (intubation), and breathing machine (ventilator)
Blood and urine tests
ECG (electrocardiogram, or heart tracing)
Fluids by IV (through a vein)
Medicines to stop vomiting
Medicines to treat severe allergic reactions (if needed), including diphenhydramine (Benadryl)

If you have shellfish poisoning, you may receive:

Blood and urine tests
ECG (electrocardiogram, or heart tracing)
Fluids by IV (through a vein)
Medicines to stop vomiting

If shellfish poisoning causes paralysis, you may have to stay in the hospital until your symptoms improve.

Outlook (Prognosis)

Fish and shellfish poisonings occur infrequently in the United States. You can protect yourself by avoiding fish and seafood caught in and around the areas of a known red tide, and by avoiding clams, mussels, and oysters during the summer months. If you are poisoned, your long-term outcome is usually quite good.

Scombroid poisoning symptoms usually only last for a few hours after medical treatment has begun. Ciguatera poisoning and shellfish poisoning symptoms may last from days to weeks, depending on the severity of the poisoning. Serious outcomes or death are rare.

There is no way for the person who prepares the food to know that their food is contaminated. Therefore, it is very important that your health care provider tell the restaurant their food is contaminated so that they can throw it away before other people become sick. Your provider should also contact the Department of Health to make sure that the suppliers providing the contaminated fish are identified and destroyed.

Jong EC. Fish and shellfish poisoning: toxic syndromes. In: Sandford CA, Pottinger PS, Jong EC, eds. The Travel and Tropical Medicine Manual. 5th ed. Philadelphia, PA: Elsevier; 2017:chap 34.

Kapil V, Bradberry SM, Pirmohamed M. Prescribing, therapeutics and toxicology. In: Feather A, Randall D, Waterhouse M, eds. Kumar and Clarke’s Clinical Medicine. 10th ed. Philadelphia, PA: Elsevier; 2021:chap 12.

Madhosingh H. Infectious diseases. In: Harward MP, ed. Medical Secrets. 6th ed. Philadelphia, PA: Elsevier; 2019:chap 12.

Morris JG. Human illness associated with harmful algal blooms. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 284.

Nitzberg M, Smereck J. Diarrhea. In: Walls RM, ed. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 27.

Last reviewed on: 1/2/2023

Reviewed by: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Fish poison is out of control

May 18, 2012, 17:58
Society

Thrill-seekers will be able to risk their lives in Tokyo restaurants as the city authorities intend to lift strict restrictions on the preparation of puffer fish, which contains high concentrations of the poison tetrodotoxin. When it enters the digestive tract, the poison causes severe pain, convulsions, and then paralysis and death due to respiratory arrest. However, there is a tradition in the country: if a visitor gets poisoned by fugu, then the cook must finish the dish.

For more than fifty years, the rule in Japan has been that in order to cook fugu, chefs must work for two years as assistants to experienced masters, and then pass a written and practical exam, paying $ 220 for it. Such cooks can correctly remove the poisonous skin from the fish, carefully remove the poisoned innards, and properly process the meat so that the remaining poison does not kill the client, but causes a feeling of slight paralysis – a narcotic effect for which diners order a dangerous dish. Tokyo City Hall has now announced that anyone can work with fugu, provided that the restaurant buys already butchered carcasses, reports BBC . It is planned that the innovation will come into effect this fall.

Previously, such proposals aroused indignation both among chefs who do not want to lose their reputation, and restaurant visitors, for whom ordering fugu is tantamount to playing Russian roulette. About 40 people are known to have been poisoned in Tokyo between 1996 and 2006. True, only one of them ate a dish in a restaurant. The rest were fishermen and ate the fish from their catch. The last case of poisoning occurred in a Tokyo restaurant in November 2011, when a woman forced the chef to cook fugu liver for her. The 35-year-old visitor knew that the liver had the most poison. As a result, the doctors had to fight for her life, and the cook lost his job.

Puffer fish is the name given to several species of fish from the pufferfish family. Most often, brown puffer or dog fish are used to prepare the dish. The body of the fish does not produce neurotoxin, it is produced by bacteria that are eaten by a variety of marine life that serves as food for pufferfish. To reduce the concentration of poison in fish, the Japanese catch fry and then feed them in special cages.

The navigator James Cook, who was fed fugu by the natives, described his sensations: “About three or four o’clock in the morning we felt an unprecedented weakness in all the members, accompanied by such a sensation as if the hands and feet, stiff in the cold, had immediately fallen into the fire. I almost felt nothing and even lost the ability to measure the heaviness of bodies: a mug of water and a pen seemed equally heavy in my hand.

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