Update: Neurologic Illness Associated with Eating Florida Pufferfish, 2002

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As of May 15, 2002, a total of 13 presumptive cases of saxitoxin poisoning were reported in Florida residents who ate pufferfish caught in waters near Titusville, Florida. Five cases were reported in April (1), and eight cases were identified through increased surveillance by Florida poison control centers, hospital emergency departments (EDs), and county health departments. This report updates the investigation of these cases.

All 13 cases occurred during January 1--April 25, 2002. Nine were identified through Florida poison control centers; four were identified by active surveillance of hospital EDs and health department foodborne illness complaint logs.

Investigators defined a case as tingling or numbness in the mouth and/or lips in a person who had eaten Florida pufferfish. All ill persons reported at least one of the following symptoms after a meal that included pufferfish: tingling or numbness in the mouth or lips (13 persons), face (eight), arms (10), legs (seven), and fingertips (one). In initial reports, two patients reported ataxia, and one reported muscle weakness. Some ill persons experienced nausea (six) and vomiting (four) before presenting to a hospital ED. Symptom onset occurred 30 minutes to approximately 8 hours after ingestion of fish (median: 2 hours). Duration of illness ranged from 10 hours to 45 days (mean: 6.6 days; median 24 hours). Eleven persons were treated in an ED, and five were admitted to the hospital. Some patients received intravenous fluids. All cases resolved.

Severity of illness was not associated with amount of pufferfish eaten, and nine meal partners who also ate the pufferfish did not become ill. Testing of approximately 25 pufferfish collected from Florida waters by the Food and Drug Administration's (FDA) Center for Food Safety and Applied Nutrition (CFSAN), in collaboration with the Florida Fish and Wildlife Conservation Commission (FWC), and additional testing by FDA's Northeast Regional Laboratory indicated that pufferfish containing potentially toxic concentrations of saxitoxins (2--53 µg saxitoxin equivalent toxicity/g) are present in the Indian River in the area of the Titusville Pier. Lower concentrations of saxitoxin have been found in pufferfish from the South Banana River.

All pufferfish related to these cases were caught in the Indian River Lagoon; 11 patients caught pufferfish off the Titusville Pier. The FWC banned retaining pufferfish caught from Volusia, Brevard, Indian River, and St. Lucie counties on April 25; the ban will remain in effect until mid-July. Information about this ban was provided at the Titusville Pier on April 30, 2002.

No filets associated with the Florida illnesses were available for testing to confirm the presence of saxitoxin. However, ongoing statewide sampling of pufferfish in Florida has indicated that pufferfish containing saxitoxins are limited to the Indian and South Banana rivers. Because saxitoxin poisoning is usually associated with mollusks, CFSAN and the Florida Department of Agriculture and Consumer Services sampled approximately 100 hard-shell clams from aquaculture lease sites at five locations along the Indian River Lagoon, including the Titusville area in Florida. Clams from two additional locations were chosen as control samples and were collected from the west coast of Florida in the Gulf of Mexico. All samples tested negative for saxitoxin.

Reported by: R Hammond, PhD, D Bodager, MPA, Florida Dept of Health; G Jackow, MA, Brevard County Health Dept, Merritt Island; P Minshew, Volusia County Health Dept, Daytona Beach; C Siegenthaler, Lake County Health Dept, Eustis; J Landsberg, PhD, Florida Marine Research Institute, Florida Fish and Wildlife Conservation Commission; D Heil, Florida Dept of Agriculture and Consumer Svcs. M Quilliam, PhD, D Wechsler, Institute for Marine Biosciences, National Research Council of Canada, Halifax. S Hall, PhD, Center for Food Safety and Applied Nutrition; T Hawryluk, MS, M Wekell, PhD, Food and Drug Administration, Jamaica, New York. S Marcus, MD, MY Wong, B Ruck, PharmD, New Jersey Poison Information and Education System, Univ of Medicine and Dentistry of New Jersey/New Jersey Medical School, Newark. H Rogers, PhD, M McGeehin, PhD, Div of Environmental Hazards and Health Effects, National Center for Environmental Health, CDC.

Editorial Note:

The initial report described 10 illnesses that were associated with pufferfish ingestion in three states (New Jersey, Virginia, and Florida) and were consistent with exposure to saxitoxins (1). One case (New Jersey) was associated with commercially purchased pufferfish from Titusville, and all other cases resulted from recreationally caught pufferfish in the Titusville area. Laboratory analysis by the Canadian Institute for Marine Biosciences of partially eaten pufferfish from the New Jersey incidents confirmed the presence of saxitoxin and two analogs (2). These results were confirmed with additional analysis by FDA's Northeast Regional Laboratory (3).

Some previous intoxications by pufferfish in Florida were attributed to tetrodotoxin (4). Seven cases of pufferfish poisoning were reported in Florida during 1951--1974, including three fatalities (5,6). These case reports were associated with ingestion of locally caught species of pufferfish Sphoeroides. A 1963 study of pufferfish from the east coast of Florida (from the Indian and Banana Rivers, including the Titusville area) demonstrated that pufferfish were toxic to mice (4). Although the species tested in this study was listed as Sphoeroides maculatus (northern pufferfish), there was confusion over the identification of this species with S. nephelus (southern pufferfish) (Figure 1). Northern pufferfish extend only as far south as Jacksonville, Florida (7), and are not known to exist in the Indian and Banana rivers.

The illnesses described in this report occurred after ingestion of pufferfish but are consistent with the presence of saxitoxin, a paralytic shellfish toxin usually associated with ingestion of filter-feeding shellfish. Concentration of saxitoxin in the pufferfish tested from the Titusville area varies. Saxitoxin has been reported in pufferfish from the Far East (8) and the Philippines (9). Shellfish containing 2--10 µg saxitoxin/g previously have caused illness (10), but saxitoxin has not previously been reported in Florida. The severity of illnesses in persons described in this report varied probably because of the concentration of saxitoxin in a particular pufferfish and/or the amount of pufferfish eaten.

Approximately 100 species of pufferfish are known worldwide, and nine species are present in Florida. Southern pufferfish populations have been increasing in the Northern Indian River during the previous 5 years (FWC, unpublished data, 2002). The southern pufferfish that have been caught recently near Titusville are normally present in this area of Florida, but they have not been implicated previously in fish poisoning events.

Sportfishers in Florida need to be educated that potentially toxic pufferfish might be in the Titusville area. Warnings about the presence of certain species of potentially toxic pufferfish should be posted in commonly fished areas. Because many sportfishers vacation in Florida and transport fish home to other states, health-care providers should be aware that rapid onset of neurologic symptoms after a meal of pufferfish could be caused by saxitoxin. Ingestion of paralytic shellfish toxins produces neurologic symptoms that are sensory, cerebellar, and motor. The most common symptoms are tingling and burning of the mouth and tongue, numbness, drowsiness, and incoherent speech. These symptoms usually occur 30 minutes to 2 hours after ingestion of the fish, depending on the amount of toxin ingested. In severe cases, ataxia, muscle weakness, respiratory paralysis, and death can occur (10). Ill persons should contact their local poison control center and proceed to a hospital ED. Hospital EDs and poison control centers should contact the local health department if persons report neurologic symptoms after eating pufferfish.

This report is based on data contributed by R Weisman, Pharm D, JL Schauben, PharmD, V Speranza, PharmD, Florida Poison Information Center; D Johnson, MD, Bur of Environmental Epidemiology, Florida Dept of Health. T Litovitz, MD, American Association of Poison Control Centers, Washington, DC. Office of Regulatory Affairs and Center for Food Safety and Applied Nutrition, Food and Drug Administration.

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