Information on the following diseases can be found in the Related Disorders section of this report:

• Tetraodon Fish Poisoning
• Scombroid Fish Poisoning
• Urticaria, Physical

The symptoms of acute ciguatera fish poisoning may begin as soon as 30 minutes after eating contaminated fish. The initial symptoms may include itching, tingling, and numbness of the lips, tongue, hands, and/or feet. Other symptoms during the first six to 17 hours are abdominal cramps, nausea, vomiting, diarrhea, and/or a red skin rash (pruritus). Chills, hot and cold temperature reversal, generalized weakness, restlessness, dizziness, wheezing, blurred vision, abnormal sensitivity to light (photophobia), muscle aches (myalgias), and/or joint pain (arthralgias) may also develop.

The acute symptoms of ciguatera fish poisoning generally disappear within a few days. However, neurological symptoms may continue for several months. Some affected individuals experience abnormally low blood pressure upon standing from a seated position (orthostatic hypotension). In severe cases, there may be rapid progression to breathing difficulties (dyspnea) and muscular paralysis. Life-threatening complications (i.e., abnormally slow heartbeat, respiratory arrest, convulsions, or coma) may occur in these severe cases within 24 hours.

Ciguatera fish poisoning is caused by a toxin (ciguatoxin) found in tropical or subtropical fish during certain times of the year. The source of the toxin responsible for ciguatera fish poisoning is found in high levels in a marine organism (dinoflagellate Gamabierdiscus toxicus) that typically inhabits low-lying tropical shore areas and coral reefs. As local fish feed on this organism, toxin accumulates in their bodies and ultimately causes ciguatera fish poisoning when humans consume the fish.

No known method of cooking can destroy the ciguatoxin in contaminated fish. It is possible that more than one form of the toxin may be present in a fish.

Ciguatera fish poisoning is a rare disease that affects males and females in equal numbers. This disease occurs with the greatest frequency in tropical and subtropical countries, particularly those in the Pacific and Caribbean areas. All age groups are at risk for this disease. However, a longer duration and more severe symptoms of ciguatera fish poisoning may be associated with increasing age. Children seem to experience milder symptoms for a shorter period of time. More severe symptoms may also be associated with the ingestion of a larger quantity of contaminated fish.

The presence of ciguatoxin has been reported in semen from affected males which can cause the symptoms of ciguatera fish poisoning in females after sexual intercourse. Since this toxin has also been identified in breast milk, it is also possible for affected mothers to pass this disease to their nursing children.

Symptoms of the following disorders can be similar to those of ciguatera fish poisoning. Comparisons may be useful for a differential diagnosis:

Tetraodon poisoning results from eating puffer fish that contain the tetraodon toxin. Symptoms are similar to those of ciguatera fish poisoning and may include abdominal cramps, nausea, vomiting, diarrhea, and/or a red itchy skin rash (pruritus). Chills, hot and cold temperature reversal, blurred vision, abnormal sensitivity to light (photophobia), and muscle aches (myalgias) may also occur. Life-threatening complications may develop in about 50 percent of cases.

Scombroid fish poisoning is caused by a toxin formed during bacterial decay of fish, and is usually associated with inadequate refrigeration. Symptoms generally begin soon after ingestion of contaminated fish and resemble those of an allergic (histamine) reaction. Symptoms may include flushing, dizziness, burning, hives (urticaria), nausea, and/or vomiting. Some people may experience swelling in the throat and difficulty breathing due to spasms which can tighten the passageway to the lungs (bronchospasm). The toxin which causes this disease is known as histamine saurine and can be found in tuna, mackerel, bonito, skipjack, and mahi mahi.

Physical Urticaria refers to a group of skin disorders characterized by red (erythematous) allergic skin lesions and itchiness (pruritus). This reaction may be produced by exposure to a variety of environmental or stress factors. The most common symptoms of Physical Urticaria are itching (pruritus) and hives consisting of red rings around white ridges (wheals). Sensitivity to cold is usually manifested by these eruptions on the skin, as well as itching, and swelling under the skin (angioedema). These symptoms develop most typically after exposure or during swimming or bathing. Contraction of the muscles around the bronchi (bronchospasm) and even shock may occur in extreme cases. (For more information on this disorder, choose "Urticaria" as your search term in the Rare Disease Database.)

The treatment for ciguatera fish poisoning is usually the immediate pumping out of all stomach contents (gastric lavage). If this treatment is not available, then vomiting should be induced by the administration of syrup of ipecac. Persistent nausea and vomiting must be treated with the intravenous administration of fluids to avoid dehydration. If shock, convulsions or respiratory failure occurs, immediate appropriate medical measures must be instituted. Dextran (a polysaccharide drug), Normal Human Serum Albumin, or blood transfusion may be necessary to treat shock. Meperidine may also be prescribed for pain. Other treatment is symptomatic and supportive.

Travelers to endemic areas should be cautioned about the risk of contracting ciguatera fish poisoning. Since travelers are at the same relative risk as people who normally live in endemic areas, they should be warned not to eat barracuda and should exercise caution when considering other fish such as grouper and red snapper.

The intravenous administration of mannitol is being investigated as a treatment for acute and/or severe cases of ciguatera fish poisoning. More studies are needed to determine the long-term safety and effectiveness of this drug before it can be universally recommended for the treatment of ciguatera fish poisoning.

Specialized laboratory tests (immunoassays) are being developed to detect very small amounts of ciguatera toxin in suspect fish. This could lead to screening and eventual prevention of ciguatera fish poisoning.

Thoene JG., ed. Physicians’ Guide to Rare Diseases. Montvale, NJ: Dowden Publishing Company Inc; 1995:827-28.

Bennett JC, Plum F., eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA: W.B. Saunders Co; 1996:1954-56.

Berkow R., ed. The Merck Manual-Home Edition. Whitehouse Station, NJ: Merck Research Laboratories; 1997:519-20.

Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:292.

REVIEW ARTICLES
Clark RF, et al., A review of selected seafood poisonings. Undersea Hyperb Med. 1999;26:175-84

Morris JG Jr., Pfiesteria, "the cell from hell," and other toxic algal nightmares. Clin Infect Dis. 1999;28:1197-98.

Sierra-Beltran AP, et al., An overview of marine food poisoning in Mexico. Toxicon. 1998;36:1493-502.

JOURNAL ARTICLES
Crump JA, et al., Ciguatera fish poisoning. Postgrad Med J. 1999;75:678-79.

Ebesu J., Ciguatera fish poisoning. CMAJ. 1999;160:1127-28.

From the Centers for Disease Control and Prevention. Ciguatera fish poisoning--Texas, 1997. JAMA.1998;280:1394-95.

Angibaud G, et al., Serious neurological manifestations of ciguatera: is the delay unusually long? J Neurol Neurosurg Psychiatry. 1998;64:688-89.