Abstract & Commentary
Synopsis: Since January 1, 2002, there have been several cases of neurologic illness reported after ingestion of pufferfish caught in waters near Titusville, Fla.
Source: Centers for Disease Control and Prevention. Neurologic illness associated with eating Florida pufferfish. MMWR Morb Mortal Wkly Rep. 2002;51:321-323.
Neurologic symptoms consistent with exposure to paralytic shellfish toxins are occurring with increasing frequency in persons after ingestion of pufferfish caught off the coast of Florida. Laboratory analysis determined the presence of saxitoxin in uneaten puffer fish. Titusville, Fla, is located south of Daytona Beach on the Atlantic Ocean.
One patient, a 34-year-old male, ate about 8 mouthfuls of pufferfish that had been caught in the waters near Titusville. His symptoms included numbness and tingling of his hands as well as vomiting and diarrhea. He was hospitalized for observation and hydration. His symptoms resolved and he was discharged after 48 hours.
A 50-year-old father and his 24-year-old son caught several pufferfish in Titusville and, upon return to their home in Virginia, cooked and ate the fish. They both began having numbness and tingling of their lips and tongues. After contacting the Richmond poison control center, they decided to monitor their symptoms at home. The son, who only had oral tingling, improved in 3-4 days. The father’s numbness and tingling did extend to involve his face, neck, and shoulders. Within 2 weeks, his symptoms had also resolved.
In New Jersey, a 65-year-old female and her husband consumed a meal of pufferfish that a family member had caught in Titusville. Both persons developed tingling around their lips within minutes of eating the fish, but the woman began vomiting and she was later hospitalized. Her course was complicated by chest pain, tachycardia, ascending paralysis, and ventilatory failure requiring mechanical ventilation. Her paralysis and muscle strength gradually improved allowing her to be extubated and discharged after 3 days.
The uneaten pufferfish from the New Jersey case were sent to the Institute for Marine Sciences in Canada. Liquid chromatographic-tandem mass spectrometric analysis detected saxitoxin and 2 similar analogs, N-sulfocarbamoylsaxitoxin and decarbamoylsaxitoxin in the fish.
Comment by Mary-Louise Scully, MD
Pufferfish, also known as swellfish, blowfish, or globefish, have the intriguing ability to inflate their bodies with air and/or water then and float upside down on the surface of the water discouraging potential attackers. Most puffers belong to the family Tertraodontidae ("four-toothed") but some include porcupinefish in the family Diodontidae ("two-toothed") as they are able to self-inflate as well. Neurotoxins (ie, saxitoxin or tetrodotoxin) can be found in several of the approximately 100 species of pufferfish. You may be familiar with the link between pufferfish and the deadly tetrodotoxin, associated with the Japanese fugu specialty. In Japanese, the word fugu is a general name for fish of the Tetraodontidae family but is also used more narrowly in that one type of puffer, Fugu rubripes, found only in the waters surrounding Japan.
These cases took place after patients ate pufferfish but are consistent with paralytic shellfish poisoning (PSP). PSP usually occurs in association with eating filter-feeding mollusks and shellfish. In the United States, about 10 cases a year of PSP are reported to the CDC. One of the best-characterized toxins involved is saxitoxin. Some freshwater cyanobacteria and dinoflagellates produce saxitoxin. Shellfish that filter to feed absorb these toxins, but nonfilter feeding shellfish, such as lobsters, crab, and shrimp, are usually safe to eat. Pufferfish, by eating mollusks, are thought to accumulate and even amplify the saxitoxin.
Saxitoxin is heat and acid stable and is not destroyed by freezing or cooking. The presence of the toxin does not affect the taste or odor of the food. Saxitoxin is rapidly absorbed after ingestion and is felt to act by blocking the opening of the voltage-sensitive sodium channel needed for propagation of nerve impulses. Symptoms of PSP include tingling of the mouth and lips, facial paresthesias, vomiting, and in severe cases ataxia, muscle weakness, respiratory paralysis, and even death.1 The time of onset and the severity of the symptoms are likely influenced by the amount of toxin ingested, though typically symptoms begin within 30 min to 2 h after ingestion.
Tetrodotoxin, also a sodium-blocking toxin, is felt to be produced by Vibrio species or other bacteria that bioaccumulate in the pufferfish. Tetrodotoxin is an extremely potent neurotoxin and is known for its association with the Japanese specialty fugu, as mentioned above. Tetrodotoxin ingestion is associated with a 60% mortality.2 Tetrodotoxin intoxication has been associated with eating pufferfish, porcupinefish, horseshoe crab eggs, and even mollusks.3 Although the symptoms begin similarly with numbness, paresthesias, and vomiting, the hallmark feature is the rapid onset of ascending paralysis, respiratory failure, and often death.
Treatment for either saxitoxin or tetrodotoxin intoxication are mainly gut decontamination and supportive care. Early intubation and mechanical ventilation can be life saving. With tetrodotoxin poisoning, there are 2 reports of reversal of motor and respiratory paralysis using edrophonium.4
Fish that are caught can often be transported to other areas. In this report, the pufferfish were caught in Titusville, Fla, but the victims of the illness were as far away as New Jersey. Until now, most pufferfish in US waters were not thought to be toxic. Now, at least 10 cases of presumed pufferfish poisoning have been reported in our waters. Chemical analysis detected the presence of saxitoxin, the toxin associated with PSP, as the cause of the symptoms in these cases. Health care providers need to be aware that the onset of neurologic symptoms after ingestion of pufferfish could be due to saxitoxin and ill persons should be advised to proceed immediately to a hospital facility.
Dr. Scully is part of the Group Health Cooperative, Puget Sound, Seattle, Wash.
References
1. Rodrigue D, et al. Lethal paralytic shellfish poisoning in Guatemala. Am J Trop Med Hyg. 1990;42:267-271.
2. Centers for Disease Control and Prevention. Tetrodotoxin poisoning associated with pufferfish transported from Japan-California, 1996. MMWR Morb Mortal Wkly Rep. 1996;45:389-391.
3. Yang CC, et al. An outbreak of tetrodotoxin poisoning following gastropod mullusk consumption. Human Exp Toxicol. 1995;14:446-450.
4. Eastaugh J, Sheperd S. Infectious and toxic syndromes from fish and shellfish consumption. A review. Arch Intern Med. 1989;149:1735-1740.
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