CDC Reports 402 Marine Toxin Outbreaks in the U.S. Over 13 Years: Scombroid and Ciguatoxin Dominate
Key Insights
During 2011–2023, 402 marine toxin-associated foodborne outbreaks were reported to CDC (search), resulting in 1,280 illnesses, 96 hospitalizations, and one death.
Scombroid toxin (search) and ciguatoxin (search) accounted for 95% of all outbreaks, with tuna implicated in 76% of scombroid cases and barracuda in 31% of ciguatoxin cases.
Shellfish-associated toxins were less frequent but more severe, with 25% of illnesses requiring hospitalization; nearly all involved recreationally harvested shellfish.
The CDC (search) has released the first comprehensive national summary of foodborne disease outbreaks caused by marine toxins in the United States, covering the period from 2011 through 2023. Published in the MMWR Surveillance Summaries, the analysis draws on data from the Foodborne Disease Outbreak Surveillance System (FDOSS) and reveals that 402 outbreaks associated with 10 distinct marine toxin etiologies were reported over the 13-year span, leading to 1,280 illnesses, 96 hospitalizations, and one death.
The national rate of reported outbreaks was 1.2 per 1 million population, with a median of 30 outbreaks per year (range: 11–52). The median number of illnesses per outbreak was two, though some outbreaks affected as many as 50 individuals. Single-state outbreaks were reported by 32 states, Washington, DC, and Puerto Rico; one multistate outbreak involving contaminated yellowfin tuna spanned 11 states.
Scombroid toxin (search): the leading cause linked to restaurants and imported fish
Scombroid toxin (search), also referred to as histamine poisoning, was responsible for 192 outbreaks (182 confirmed, 10 suspected), resulting in 597 illnesses and six hospitalizations. The toxin arises when fish are improperly refrigerated after being caught, allowing bacteria with high histidine carboxylase activity to produce elevated histamine levels. Tuna was the implicated food in 144 of the 189 scombroid outbreaks (76%) that identified a food source.
New York reported the highest number of scombroid outbreaks (43), followed by Florida (38), California (23), and Hawaii (18). Notably, 53% of scombroid outbreak reports with known importation status implicated imported fish. Restaurants were the predominant setting: among 181 outbreak reports identifying a single location of food preparation, sit-down dining restaurants accounted for 104 outbreaks (57%). None of the implicated foods in scombroid outbreaks were recreationally harvested.
Ciguatoxin (search): a recreational fishing hazard concentrated in endemic regions
Ciguatoxin (search) caused 189 outbreaks (174 confirmed, 15 suspected), with 619 illnesses and 67 hospitalizations — the highest hospitalization burden of any single toxin. Unlike scombroid toxin (search), ciguatoxin originates from algae (primarily Gambierdiscus species) and bioaccumulates in reef fish. Standard food safety practices such as temperature control do not mitigate the risk.
Florida (88 outbreaks, 274 illnesses), Puerto Rico (55 outbreaks, 185 illnesses), and Hawaii (18 outbreaks, 54 illnesses) accounted for the vast majority of ciguatoxin (search) outbreaks. Barracuda was implicated in 58 outbreaks (31%), followed by grouper (25 outbreaks, 13%) and amberjack (22 outbreaks, 12%). Among outbreak reports with importation data, 87% involved domestically caught fish. Of the 60 reports with harvesting information, 60% indicated the fish were recreationally harvested, and 80% of outbreaks with a known preparation location were linked to private homes.
Shellfish-associated toxins: rare but disproportionately severe
Thirteen outbreaks were attributed to shellfish-associated toxins, including six outbreaks of paralytic shellfish poisoning (search) (23 illnesses, four hospitalizations), four of neurotoxic shellfish poisoning (search) (10 illnesses, three hospitalizations), and one each of amnesic shellfish poisoning (search), diarrhetic shellfish poisoning (search), and an unknown shellfish toxin. Despite accounting for only 3% of all outbreaks, these events carried a hospitalization rate of 25%.
Florida reported five shellfish-toxin outbreaks and Alaska reported four. Mussels and sea snails were each implicated in four outbreaks, and clams in three. All 11 outbreak reports with importation status involved domestically caught shellfish, and 86% of reports with harvesting information indicated recreational harvesting. Among outbreaks with a known preparation location, 73% were associated with private homes.
Other marine toxins and the lone fatality
Eight additional outbreaks were caused by three other marine toxins: four by an unidentified toxin associated with Haff disease (search) (11 illnesses, 10 hospitalizations, and the only reported death), three by puffer fish tetrodotoxin (search) (nine illnesses, four hospitalizations), and one by an unspecified fish toxin (four illnesses). Buffalo fish and puffer fish were the most commonly implicated species in this category, and 86% of these outbreaks involved fish prepared in a private home.
Implications for prevention and public health
The CDC (search) analysis underscores divergent prevention strategies for different marine toxins. For scombroid toxin (search), the findings highlight the need for improved temperature control throughout the seafood supply chain — particularly for imported fish — and enhanced food safety practices at restaurants. For ciguatoxin (search) and shellfish-associated toxins, the report emphasizes that interventions must incorporate a collaborative, multisectoral One Health approach, including environmental monitoring of algal blooms and targeted education for recreational fishers and harvesters.
The authors note that climate-related changes, including warming waters and expanding geographic ranges of toxin-producing algae, may increase the presence of marine toxins in commercially and recreationally harvested fish and shellfish. With imported seafood comprising an estimated 80% to more than 90% of all domestically consumed seafood in the United States, the report calls for continued vigilance across the global seafood supply chain.