Facts on ciguatera fish poisoning


Disclaimer: The information contained in this factsheet is intended for general information and should not substitute individual expert advice or the judgement of healthcare professionals. 

Ciguatera poisoning (CP) is caused by consumption of fish that have accumulated ciguatoxins in their flesh. CP is endemic in tropical and subtropical regions, particularly in the Pacific and Indian Oceans and the Caribbean Sea. Isolated outbreaks have occurred sporadically in Europe but with an increasing frequency in temperate areas like the Canary Islands, Spain.

CP is not under routine surveillance in the European Union (EU), but unexpected, potentially serious cross-border biological threats to health are monitored by ECDC [1]. Cases are usually not notified in national surveillance systems but may be reported to national poisoning centres. 


Ciguatoxins (CTXs) are temperature-stable, so they are not destroyed by cooking or by freezing the fish. Furthermore, the toxins are colourless, odourless, and flavourless, which make it impossible to taste or smell them [2,3].


CP is caused by the consumption of herbivorous fish that feed on toxic microalgae (Gambierdiscus spp. and Fukuyoa spp.), which are attached to macrophytes or dead corals, and from carnivorous fish that have consumed toxic herbivorous fish [3,4].

Over 400 known fish species from tropical and subtropical waters have been classified as potential carriers of CTXs. Examples of the fish most frequently associated with cases of CP include barracuda, grouper, amberjack, snapper, moray eel, hogfish, mackerel, surgeonfish, and parrotfish. Greater severity of illness is associated with eating fish head or organs. It is therefore advisable to avoid consuming visceral organs, roe (fish eggs), and carcasses (e.g. heads, eyes, and bones) of these fish species [4-6].

Person-to-person transmission of CTXs is extremely rare, but transmission of toxin from mother to child during breastfeeding or across the placenta, as well as during sexual intercourse, has been described [6-10].

Clinical features and sequelae

Intoxication of humans occurs via consumption of fish containing CTXs. In humans, CTXs activate voltage-gated sodium channels in cell membranes, increasing sodium ion permeability and depolarizing the nerve cell. Clinical presentation varies according to the individual characteristics and the geographical origin of the CTXs. Gastrointestinal symptoms can precede or accompany neurological symptoms, which usually appear two to 48 hours after eating the contaminated fish. Symptoms can include nausea, vomiting, diarrhoea, abdominal cramps, paraesthesia of lips, tongue and extremities, cold allodynia (burning pain caused by a normally innocuous cold stimulus), a metallic taste in the mouth, arthralgia, myalgia, pruritus without urticaria or erythema, muscle weakness, blurred vision, painful intercourse, hypotension, and bradycardia [4,8,11].

Cold allodynia is characteristic of CP, although it is not present in all patients. Neurological symptoms usually resolve within weeks, although some symptoms can last for months. Recurrent symptoms can occur following the ingestion of certain food or beverages such as alcohol, nuts, or non-toxic fish. CP is rarely fatal, but death can occur in severe cases due to severe dehydration, cardiovascular shock, or respiratory failure [4,8,11].


CP is one of the most common foodborne poisonings related to finfish consumption, but its true incidence is not known. The prevalence in endemic areas ranges from 0.1 percent of the population in regions like Queensland (Australia) or Florida (the United States of America) to more than 50 percent in small South Pacific or Caribbean islands [4,11,12].

In the last 20 years, several cases of CP have been reported in Europe by travellers to endemic countries, as well as through the consumption of imported contaminated fish [7,8,13,14]. CP can cause outbreaks among consumers who have bought locally caught marine fish from seafood shops. Ciguatera outbreaks due to the consumption of autochthonous fish have also been reported in Madeira (Portugal) and the Canary Islands (Spain) [6,9,10,15-18].

Global environmental changes, notably climate change, might foster the distribution and proliferation of the microalgae that produce CTXs [19-21]. In addition, globalisation of the fish trade might also contribute to the spread of ciguatoxic fish and thus increase the risk for poisoning due to the consumption of imported fish in non-endemic regions [7,8].


No reliable laboratory testing to detect CTXs in human clinical samples are available, but tests are available for the detection of CTXs in fish [22,23]. Semi-quantitative methods, including in vitro cytotoxicity or the receptor-binding assays, can detect all active toxin analogues that present a CTX-like toxicity. Although these assays do not provide information on toxin profiles, they can be applied as screening methods for CTXs. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods allow specific detection of individual toxin analogues of Pacific, Caribbean and Indian Ocean CTXs, as well as CTXs’ quantification in fish extracts [24-26]. None of the currently available analytical methods have been formally validated. The maximum limits for CTXs in fish have not been established for regulatory purposes in the EU, but the regulation requires that no fish products containing CTX-group toxins are placed on the market [22].

The diagnosis in humans is mainly based on recent history of fish consumption and clinical presentation. Diagnosis is supported if several individuals develop similar symptoms and report a common history of seafood consumption. As several other marine toxin poisonings cause partially similar symptoms to CP, it is important to rule these out by obtaining a thorough history of recent seafood consumption. If the recent seafood consumption history identifies shellfish but not finfish consumption, other marine intoxications are more likely.

Case management and treatment 

There is no specific treatment; treatment focuses on symptomatic and supportive care [3,4]. 

Public health prevention and control measures 

In the event of suspected CP, food handlers are advised to keep any food remnants or parts of the consumed fish frozen at -20ºC, and to contact the local food safety authority.

Fishermen should avoid fishing in areas where cases and outbreaks have occurred or where a suspicion of the presence of ciguatoxin-containing microalgae is reported. These precautions should be taken throughout the year, as ciguatera is not seasonal. Preventing toxic fish entering markets is the most effective way of preventing outbreaks in the EU [27].

Prevention and control

Avoiding the consumption of large predatory reef fish from affected areas could help preventing CP, although in some areas the consumption of smaller carnivorous and herbivorous fish can also present a high risk for poisoning. Local information about fish species causing ciguatera in the region should be considered, and any available instructions by local food safety authorities followed. If possible, the consumption of fish of uncertain origin or untraceable point of sale should be avoided. The identification and removal of toxic fish from the food chain is a priority to prevent the occurrence of further cases.

Raising awareness among healthcare professionals, especially in endemic areas, can help diagnose cases faster.

Since CTXs can be transmitted through breastfeeding and unprotected sexual intercourse, advice to refrain from breastfeeding and/or unprotected sexual intercourse should be considered while symptomatic.

If you suspect you have CP, seek medical attention and keep in mind that ingesting certain beverages and food (mainly alcohol, fish, and nuts) can trigger the recurrent occurrence of symptoms up to three to six months from ingestion of ciguatera toxin. Patients with ciguatera symptoms should be asked thoroughly about the types of fish they have consumed as well as consumption times and places if possible.

Advice to travellers 

Disclaimer: Travel health physicians and travellers should always first consult national travel guidelines and recommendations as the primary source of information. 

The general recommendation is that travel health physicians and travellers should consult national travel guidelines and recommendations as the primary source of information.

Travellers to endemic areas should be aware of the risks related to the consumption of certain fish species (named above). Fish should only be bought from controlled seafood markets. 

Further reading

EuroCigua II is a joint project by the European Food Safety Authority (EFSA) and Spain’s Ministry of Health with the main aim to provide the basis for an integrated approach to assessing the human health risks of ciguatoxins in fish in Europe. The project includes the epidemiological characterisation of CP cases, the full characterisation of the profiles of CTXs involved in CP, the establishment of training programs for the laboratory detection of CTXs in fish, the production of reference materials, the risk characterisation of CP due to imported fish, and the initiation of the work for predictive modelling on ciguatera in Europe [28].

The Food and Agriculture Organization (FAO) and the World Health Organization’s (WHO) joint report of the Expert Meeting on Ciguatera Poisoning, Rome 19–23 November 2018, has been published online as part of the AG Food Safety and Quality Series [5].


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