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Factsheet for health professionals on ciguatera fish poisoning

Factsheet

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

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].

Transmission

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].

Epidemiology

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].

Diagnostics

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].

References

  1. Regulation (EU) 2022/2370 of the European Parliament and of the Council of 23 November 2022 amending Regulation (EC) No 851/2004 establishing a European centre for disease prevention and control2022; L 314:[25 p.]. Available at: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=uriserv%3AOJ.L_.2022.314.01.0001.01.ENG&toc=OJ%3AL%3A2022%3A314%3ATOC
  2. Bidard JN, Vijverberg HP, Frelin C, Chungue E, Legrand AM, Bagnis R, et al. Ciguatoxin is a novel type of Na+ channel toxin. J Biol Chem. 1984 Jul 10;259(13):8353-7. Available at: https://www.ncbi.nlm.nih.gov/pubmed/6330108
  3. Friedman MA, Fleming LE, Fernandez M, Bienfang P, Schrank K, Dickey R, et al. Ciguatera fish poisoning: treatment, prevention and management. Mar Drugs. 2008;6(3):456-79. Available at: https://www.ncbi.nlm.nih.gov/pubmed/19005579
  4. Friedman MA, Fernandez M, Backer LC, Dickey RW, Bernstein J, Schrank K, et al. An Updated Review of Ciguatera Fish Poisoning: Clinical, Epidemiological, Environmental, and Public Health Management. Mar Drugs. 2017 Mar 14;15(3) Available at: https://www.ncbi.nlm.nih.gov/pubmed/28335428
  5. Food and Agriculture Organization of the United Nations. Report of the Expert Meeting on Ciguatera Poisoning, Rome, 19-23 November 2018. FAO and WHO; 2018. Available at: https://www.fao.org/documents/card/en/c/ca8817en
  6. Perez-Arellano JL, Luzardo OP, Perez Brito A, Hernandez Cabrera M, Zumbado M, Carranza C, et al. Ciguatera fish poisoning, Canary Islands. Emerg Infect Dis. 2005 Dec;11(12):1981-2. Available at: https://www.ncbi.nlm.nih.gov/pubmed/16485501
  7. Centers for Disease Control and Prevention (CDC). Ciguatera fish poisoning - New York City, 2010-2011. MMWR Morbidity and mortality weekly report. 2013; 62(4):[61-5 pp.]. Available at: https://pubmed.ncbi.nlm.nih.gov/23364271/
  8. Friedemann M. Ciguatera fish poisoning outbreaks from 2012 to 2017 in Germany caused by snappers from India, Indonesia, and Vietnam. Journal of Consumer Protection and Food Safety. 2019 2019/03/01;14(1):71-80. Available at: https://doi.org/10.1007/s00003-018-1191-8
  9. Nunez D, Matute P, Garcia A, Garcia P, Abadia N. Outbreak of ciguatera food poisoning by consumption of amberjack (Seriola spp.) in the Canary Islands, May 2012. Euro Surveill. 2012 Jun 7;17(23) Available at: https://www.ncbi.nlm.nih.gov/pubmed/22720739
  10. Otero P, Perez S, Alfonso A, Vale C, Rodriguez P, Gouveia NN, et al. First toxin profile of ciguateric fish in Madeira Arquipelago (Europe). Anal Chem. 2010 Jul 15;82(14):6032-9. Available at: https://www.ncbi.nlm.nih.gov/pubmed/20557036
  11. Dickey RW, Plakas SM. Ciguatera: a public health perspective. Toxicon. 2010 Aug 15;56(2):123-36. Available at: https://www.ncbi.nlm.nih.gov/pubmed/19782098
  12. Skinner MP, Brewer TD, Johnstone R, Fleming LE, Lewis RJ. Ciguatera fish poisoning in the Pacific Islands (1998 to 2008). PLoS Negl Trop Dis. 2011 Dec;5(12):e1416. Available at: https://www.ncbi.nlm.nih.gov/pubmed/22180797
  13. Bavastrelli M, Bertucci P, Midulla M, Giardini O, Sanguigni S. Ciguatera fish poisoning: an emerging syndrome in Italian travelers. J Travel Med. 2001 May-Jun;8(3):139-42. Available at: https://www.ncbi.nlm.nih.gov/pubmed/11468116
  14. Develoux M, Le Loup G, Pialoux G. A case of ciguatera fish poisoning in a French traveler. Euro Surveill. 2008 Nov 6;13(45):pii: 19027. Available at: https://www.ncbi.nlm.nih.gov/pubmed/19000571
  15. Boada LD, Zumbado M, Luzardo OP, Almeida-Gonzalez M, Plakas SM, Granade HR, et al. Ciguatera fish poisoning on the West Africa Coast: An emerging risk in the Canary Islands (Spain). Toxicon. 2010 Dec;56(8):1516-9. Available at: https://www.ncbi.nlm.nih.gov/pubmed/20692274
  16. Boucaud-Maitre D, Vernoux JP, Pelczar S, Daudens-Vaysse E, Aubert L, Boa S, et al. Incidence and clinical characteristics of ciguatera fish poisoning in Guadeloupe (French West Indies) between 2013 and 2016: a retrospective cases-series. Sci Rep. 2018 Feb 15;8(1):3095. Available at: https://www.ncbi.nlm.nih.gov/pubmed/29449664
  17. Bravo J, Su FC, Ram AS, Acosta F. Ciguatera, an Emerging Human Poisoning in Europe. Journal of Aquaculture & Marine Biology. 2015; 3(1). Available at: https://medcraveonline.com/JAMB/ciguatera-an-emerging-human-poisoning-in-europe.html
  18.  Costa PR, Estevez P, Castro D, Solino L, Gouveia N, Santos C, et al. New Insights into the Occurrence and Toxin Profile of Ciguatoxins in Selvagens Islands (Madeira, Portugal). Toxins (Basel). 2018; 10(12). Available at: https://www.ncbi.nlm.nih.gov/pubmed/30544529
  19. Botana LM. Toxicological Perspective on Climate Change: Aquatic Toxins. Chem Res Toxicol. 2016; 29(4):[619-25 pp.]. Available at: https://www.ncbi.nlm.nih.gov/pubmed/26958981
  20. Gingold DB, Strickland MJ, Hess JJ. Ciguatera fish poisoning and climate change: analysis of National Poison Center Data in the United States, 2001-2011. Environ Health Perspect. 2014; 122(6):[580-6 pp.]. Available at: https://www.ncbi.nlm.nih.gov/pubmed/24618280
  21. Sangil C, Sansón M, Afonso-Carrillo J, Herrera R, Rodríguez A, Martín-García L, et al. Changes in subtidal assemblages in a scenario of warming: Proliferations of ephemeral benthic algae in the Canary Islands (eastern Atlantic Ocean). Marine Environmental Research. 2012; 77:[120-8 pp.]. Available at: http://www.sciencedirect.com/science/article/pii/S0141113612000645
  22. EFSA Panel on Contaminants in the Food Chain. Scientific Opinion on marine biotoxins in shellfish – Emerging toxins: Ciguatoxin group. EFSA Journal. 2010; 8(6):[1627 p.]. Available at: https://efsa.onlinelibrary.wiley.com/doi/abs/10.2903/j.efsa.2010.1627
  23. Estevez P, Sibat M, Leao-Martins JM, Reis Costa P, Gago-Martinez A, Hess P. Liquid Chromatography Coupled to High-Resolution Mass Spectrometry for the Confirmation of Caribbean Ciguatoxin-1 as the Main Toxin Responsible for Ciguatera Poisoning Caused by Fish from European Atlantic Coasts. Toxins (Basel). 2020 Apr 21;12(4) Available at: https://www.ncbi.nlm.nih.gov/pubmed/32326183
  24. Caillaud A, Eixarch H, de la Iglesia P, Rodriguez M, Dominguez L, Andree KB, et al. Towards the standardisation of the neuroblastoma (neuro-2a) cell-based assay for ciguatoxin-like toxicity detection in fish: application to fish caught in the Canary Islands. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2012;29(6):1000-10. Available at: https://www.ncbi.nlm.nih.gov/pubmed/22394180
  25. Estevez P, Castro D, Manuel Leao J, Yasumoto T, Dickey R, Gago-Martinez A. Implementation of liquid chromatography tandem mass spectrometry for the analysis of ciguatera fish poisoning in contaminated fish samples from Atlantic coasts. Food Chem. 2019 May 15;280:8-14. Available at: https://www.ncbi.nlm.nih.gov/pubmed/30642510
  26. Estevez P, Leao JM, Yasumoto T, Dickey RW, Gago-Martinez A. Caribbean Ciguatoxin-1 stability under strongly acidic conditions: Characterisation of a new C-CTX1 methoxy congener. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2020 Mar;37(3):519-29. Available at: https://www.ncbi.nlm.nih.gov/pubmed/31881166
  27. Sanchez-Henao JA, García-Álvarez N, Fernández A, Saavedra P, Silva Sergent F, Padilla D, et al. Predictive score and probability of CTX-like toxicity in fish samples from the official control of ciguatera in the Canary Islands. The Science of the total environment. 2019; 673:[576-84 pp.]. Available at: https://pubmed.ncbi.nlm.nih.gov/30999098/
  28. Ministry of Health: Spain. EuroCigua II: “An integrated approach to assess the human health risks of ciguatoxins in fish in Europe” 2024. Available at: https://www.sanidad.gob.es/en/areas/sanidadExterior/euroCiguaII/home.htm

Page last updated 25 Apr 2024