Ciguatera fish poisoning in the Caribbean islands and Western Atlantic

Ciguatera Fish Poisoning in the Caribbean Sea and Atlantic Ocean: Reconciling the Multiplicity of Ciguatoxins and Analytical Chemistry Approach for Public Health Safety

Ciguatera is a major circumtropical poisoning caused by the consumption of marine fish and invertebrates contaminated with ciguatoxins (CTXs): neurotoxins produced by endemic and benthic dinoflagellates which are biotransformed in the fish food-web. We provide a history of ciguatera research conducted over the past 70 years on ciguatoxins from the Pacific Ocean (P-CTXs) and Caribbean Sea (C-CTXs) and describe their main chemical, biochemical, and toxicological properties. Currently, there is no official method for the extraction and quantification of ciguatoxins, regardless their origin, mainly due to limited CTX-certified reference materials. In this review, the extraction and purification procedures of C-CTXs are investigated, considering specific objectives such as isolating reference materials, analysing fish toxin profiles, or ensuring food safety control. Certain in vitro assays may provide sufficient sensitivity to detect C-CTXs at sub-ppb levels in fish, but they do not allow for individual identification of CTXs. Recent advances in analysis using liquid chromatography coupled with low- or high-resolution mass spectrometry provide new opportunities to identify known C-CTXs, to gain structural insights into new analogues, and to quantify C-CTXs. Together, these methods reveal that ciguatera arises from a multiplicity of CTXs, although one major form (C-CTX-1) seems to dominate. However, questions arise regarding the abundance and instability of certain C-CTXs, which are further complicated by the wide array of CTX-producing dinoflagellates and fish vectors. Further research is needed to assess the toxic potential of the new C-CTX and their role in ciguatera fish poisoning. With the identification of C-CTXs in the coastal USA and Eastern Atlantic Ocean, the investigation of ciguatera fish poisoning is now a truly global effort.

Florida’s Harmful Algal Bloom (HAB) Problem: Escalating Risks to Human, Environmental and Economic Health With Climate Change

Harmful Algal Blooms (HABs) pose unique risks to the citizens, stakeholders, visitors, environment and economy of the state of Florida. Florida has been historically subjected to reoccurring blooms of the toxic marine dinoflagellate Karenia brevis (C. C. Davis) G. Hansen & Moestrup since at least first contact with explorers in the 1500’s. However, ongoing immigration of more than 100,000 people year–1 into the state, elevated population densities in coastal areas with attendant rapid, often unregulated development, coastal eutrophication, and climate change impacts (e.g., increasing hurricane severity, increases in water temperature, ocean acidification and sea level rise) has likely increased the occurrence of other HABs, both freshwater and marine, within the state as well as the number of people impacted by these blooms. Currently, over 75 freshwater, estuarine, coastal and marine HAB species are routinely monitored by state agencies. While only blooms of K. brevis, the dinoflagellate Pyrodinium bahamense (Böhm) Steidinger, Tester, and Taylor and the diatom Pseudo-nitzschia spp. have resulted in closure of commercial shellfish beds, other HAB species, including freshwater and marine cyanobacteria, pose either imminent or unknown risks to human, environmental and economic health. HAB related human health risks can be classified into those related to consumption of contaminated shellfish and finfish, consumption of or contact with bloom or toxin contaminated water or exposure to aerosolized HAB toxins. While acute human illnesses resulting from consumption of brevetoxin-, saxitoxin-, and domoic acid-contaminated commercial shellfish have been minimized by effective monitoring and regulation, illnesses due to unregulated toxin exposures, e.g., ciguatoxins and cyanotoxins, are not well documented or understood. Aerosolized HAB toxins potentially impact the largest number of people within Florida. While short-term (days to weeks) impacts of aerosolized brevetoxin exposure are well documented (e.g., decreased respiratory function for at-risk subgroups such as asthmatics), little is known of longer term (>1 month) impacts of exposure or the risks posed by aerosolized cyanotoxin [e.g., microcystin, β-N-methylamino-L-alanine (BMAA)] exposure. Environmental risks of K. brevis blooms are the best studied of Florida HABs and include acute exposure impacts such as significant dies-offs of fish, marine mammals, seabirds and turtles, as well as negative impacts on larval and juvenile stages of many biota. When K. brevis blooms are present, brevetoxins can be found throughout the water column and are widespread in both pelagic and benthic biota. The presence of brevetoxins in living tissue of both fish and marine mammals suggests that food web transfer of these toxins is occurring, resulting in toxin transport beyond the spatial and temporal range of the bloom such that impacts of these toxins may occur in areas not regularly subjected to blooms. Climate change impacts, including temperature effects on cell metabolism, shifting ocean circulation patterns and changes in HAB species range and bloom duration, may exacerbate these dynamics. Secondary HAB related environmental impacts are also possible due to hypoxia and anoxia resulting from elevated bloom biomass and/or the decomposition of HAB related mortalities. Economic risks related to HABs in Florida are diverse and impact multiple stakeholder groups. Direct costs related to human health impacts (e.g., increased hospital visits) as well as recreational and commercial fisheries can be significant, especially with wide-spread sustained HABs. Recreational and tourism-based industries which sustain a significant portion of Florida’s economy are especially vulnerable to both direct (e.g., declines in coastal hotel occupancy rates and restaurant and recreational users) and indirect (e.g., negative publicity impacts, associated job losses) impacts from HABs. While risks related to K. brevis blooms are established, Florida also remains susceptible to future HABs due to large scale freshwater management practices, degrading water quality, potential transport of HABs between freshwater and marine systems and the state’s vulnerability to climate change impacts.

Ciguatera Mini Review: 21st Century Environmental Challenges and the Interdisciplinary Research Efforts Rising to Meet Them

Globally, the livelihoods of over a billion people are affected by changes to marine ecosystems, both structurally and systematically. Resources and ecosystem services, provided by the marine environment, contribute nutrition, income, and health benefits for communities. One threat to these securities is ciguatera poisoning; worldwide, the most commonly reported non-bacterial seafood-related illness. Ciguatera is caused by the consumption of (primarily) finfish contaminated with ciguatoxins, potent neurotoxins produced by benthic single-cell microalgae. When consumed, ciguatoxins are biotransformed and can bioaccumulate throughout the food-web via complex pathways. Ciguatera-derived food insecurity is particularly extreme for small island-nations, where fear of intoxication can lead to fishing restrictions by region, species, or size. Exacerbating these complexities are anthropogenic or natural changes occurring in global marine habitats, e.g., climate change, greenhouse-gas induced physical oceanic changes, overfishing, invasive species, and even the international seafood trade. Here we provide an overview of the challenges and opportunities of the 21st century regarding the many facets of ciguatera, including the complex nature of this illness, the biological/environmental factors affecting the causative organisms, their toxins, vectors, detection methods, human-health oriented responses, and ultimately an outlook towards the future. Ciguatera research efforts face many social and environmental challenges this century. However, several future-oriented goals are within reach, including digital solutions for seafood supply chains, identifying novel compounds and methods with the potential for advanced diagnostics, treatments, and prediction capabilities. The advances described herein provide confidence that the tools are now available to answer many of the remaining questions surrounding ciguatera and therefore protection measures can become more accurate and routine.

Marine harmful algal blooms (HABs) in the United States: History, current status and future trends

Harmful algal blooms (HABs) are diverse phenomena involving multiple. species and classes of algae that occupy a broad range of habitats from lakes to oceans and produce a multiplicity of toxins or bioactive compounds that impact many different resources. Here, a review of the status of this complex array of marine HAB problems in the U.S. is presented, providing historical information and trends as well as future perspectives. The study relies on thirty years (1990-2019) of data in HAEDAT - the IOC-ICES-PICES Harmful Algal Event database, but also includes many other reports. At a qualitative level, the U.S. national HAB problem is far more extensive than was the case decades ago, with more toxic species and toxins to monitor, as well as a larger range of impacted resources and areas affected. Quantitatively, no significant trend is seen for paralytic shellfish toxin (PST) events over the study interval, though there is clear evidence of the expansion of the problem into new regions and the emergence of a species that produces PSTs in Florida - Pyrodinium bahamense. Amnesic shellfish toxin (AST) events have significantly increased in the U.S., with an overall pattern of frequent outbreaks on the West Coast, emerging, recurring outbreaks on the East Coast, and sporadic incidents in the Gulf of Mexico. Despite the long historical record of neurotoxic shellfish toxin (NST) events, no significant trend is observed over the past 30 years. The recent emergence of diarrhetic shellfish toxins (DSTs) in the U.S. began along the Gulf Coast in 2008 and expanded to the West and East Coasts, though no significant trend through time is seen since then. Ciguatoxin (CTX) events caused by Gambierdiscus dinoflagellates have long impacted tropical and subtropical locations in the U.S., but due to a lack of monitoring programs as well as under-reporting of illnesses, data on these events are not available for time series analysis. Geographic expansion of Gambierdiscus into temperate and non-endemic areas (e.g., northern Gulf of Mexico) is apparent, and fostered by ocean warming. HAB-related marine wildlife morbidity and mortality events appear to be increasing, with statistically significant increasing trends observed in marine mammal poisonings caused by ASTs along the coast of California and NSTs in Florida. Since their first occurrence in 1985 in New York, brown tides resulting from high-density blooms of Aureococcus have spread south to Delaware, Maryland, and Virginia, while those caused by Aureoumbra have spread from the Gulf Coast to the east coast of Florida. Blooms of Margalefidinium polykrikoides occurred in four locations in the U.S. from 1921-2001 but have appeared in more than 15  U.S. estuaries since then, with ocean warming implicated as a causative factor. Numerous blooms of toxic cyanobacteria have been documented in all 50  U.S. states and the transport of cyanotoxins from freshwater systems into marine coastal waters is a recently identified and potentially significant threat to public and ecosystem health. Taken together, there is a significant increasing trend in all HAB events in HAEDAT over the 30-year study interval. Part of this observed HAB expansion simply reflects a better realization of the true or historic scale of the problem, long obscured by inadequate monitoring. Other contributing factors include the dispersion of species to new areas, the discovery of new HAB poisoning syndromes or impacts, and the stimulatory effects of human activities like nutrient pollution, aquaculture expansion, and ocean warming, among others. One result of this multifaceted expansion is that many regions of the U.S. now face a daunting diversity of species and toxins, representing a significant and growing challenge to resource managers and public health officials in terms of toxins, regions, and time intervals to monitor, and necessitating new approaches to monitoring and management. Mobilization of funding and resources for research, monitoring and management of HABs requires accurate information on the scale and nature of the national problem. HAEDAT and other databases can be of great value in this regard but efforts are needed to expand and sustain the collection of data regionally and nationally.

Evidence for the Range Expansion of Ciguatera in French Polynesia: A Revisit of the 2009 Mass-Poisoning Outbreak in Rapa Island (Australes Archipelago)

Ciguatera poisoning (CP) results from the consumption of seafood contaminated with ciguatoxins (CTXs). This disease is highly prevalent in French Polynesia with several well-identified hotspots. Rapa Island, the southernmost inhabited island in the country, was reportedly free of CP until 2007. This study describes the integrated approach used to investigate the etiology of a fatal mass-poisoning outbreak that occurred in Rapa in 2009. Symptoms reported in patients were evocative of ciguatera. Several Gambierdiscus field samples collected from benthic assemblages tested positive by the receptor binding assay (RBA). Additionally, the toxicity screening of ≈250 fish by RBA indicated ≈78% of fish could contain CTXs. The presence of CTXs in fish was confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The potential link between climate change and this range expansion of ciguatera to a subtropical locale of French Polynesia was also examined based on the analysis of temperature time-series data. Results are indicative of a global warming trend in Rapa area. A five-fold reduction in incidence rates was observed between 2009 and 2012, which was due in part to self-regulating behavior among individuals (avoidance of particular fish species and areas). Such observations underscore the prominent role played by community outreach in ciguatera risk management.

Neurological Disturbances of Ciguatera Poisoning: Clinical Features and Pathophysiological Basis

Ciguatera fish poisoning (CFP), the most prevalent seafood poisoning worldwide, is caused by the consumption of tropical and subtropical fish contaminated with potent neurotoxins called ciguatoxins (CTXs). Ciguatera is a complex clinical syndrome in which peripheral neurological signs predominate in the acute phase of the intoxication but also persist or reoccur long afterward. Their recognition is of particular importance in establishing the diagnosis, which is clinically-based and can be a challenge for physicians unfamiliar with CFP. To date, no specific treatment exists. Physiopathologically, the primary targets of CTXs are well identified, as are the secondary events that may contribute to CFP symptomatology. This review describes the clinical features, focusing on the sensory disturbances, and then reports on the neuronal targets and effects of CTXs, as well as the neurophysiological and histological studies that have contributed to existing knowledge of CFP neuropathophysiology at the molecular, neurocellular and nerve levels.

Global impact of ciguatoxins and ciguatera fish poisoning on fish, fisheries and consumers

Ciguatera fish poisoning (CFP) is one of the most devastating food-borne illnesses caused by fish consumption. Ciguatoxins (CTXs) are potent neurotoxins synthesized by the benthic microalgae Gambierdiscus spp. and Fukuyoa spp. that are transmitted to fish by grazing and predation. Despite the high incidence of CFP, affecting an estimated number of 50,000 persons per year in tropical and subtropical latitudes, the factors underlying CTXs occurrence are still not well understood. Toxin transfer and dynamics in fish and food-webs are complex. Feeding habits and metabolic pathways determine the toxin profile and toxicity of fish, and migratory species may transport and spread the hazard. Furthermore, CTX effect on fish may be a limiting factor for fish recruitment and toxin prevalence. Recently, new occurrences of Gambierdiscus spp. in temperate areas have been concomitant with the detection of toxic fish and CFP incidents in non-endemic areas. CFP cases in Europe have led to implementation of monitoring programs and fisheries restrictions with considerable impact on local economies. More than 400 species of fish can be vectors of CTXs, and most of them are high-valued commercial species. Thus, the risk uncertainty and the spread of Gambierdiscus have serious consequences for fisheries and food safety. Here, we present a critical review of CTXs impacts on fish, fisheries, and humans, based on the current knowledge on CFP incidence and CTXs prevalence in microalgae and fish.

Ciguatoxin Occurrence in Food-Web Components of a Cuban Coral Reef Ecosystem: Risk-Assessment Implications

In Cuba, ciguatera poisoning associated with fish consumption is the most commonly occurring non-bacterial seafood-borne illness. Risk management through fish market regulation has existed in Cuba for decades and consists of bans on selected species above a certain weight; however, the actual occurrence of ciguatoxins (CTXs) in seafood has never been verified. From this food safety risk management perspective, a study site locally known to be at risk for ciguatera was selected. Analysis of the epiphytic dinoflagellate community identified the microalga Gambierdiscus. Gambierdiscus species included six of the seven species known to be present in Cuba (G. caribaeus, G. belizeanus, G. carpenteri, G. carolinianus, G. silvae, and F. ruetzleri). CTX-like activity in invertebrates, herbivorous and carnivorous fishes were analyzed with a radioligand receptor-binding assay and, for selected samples, with the N2A cell cytotoxicity assay. CTX activity was found in 80% of the organisms sampled, with toxin values ranging from 2 to 8 ng CTX3C equivalents g⁻¹ tissue. Data analysis further confirmed CTXs trophic magnification. This study constitutes the first finding of CTX-like activity in marine organisms in Cuba and in herbivorous fish in the Caribbean. Elucidating the structure–activity relationship and toxicology of CTX from the Caribbean is needed before conclusions may be drawn about risk exposure in Cuba and the wider Caribbean.

Junctional bradycardia caused by ciguatera intoxication

Ciguatera is a common but underreported tropical disease caused by the consumption of coral reef fish contaminated by ciguatoxins. Gastrointestinal and neurological symptoms predominate, but may be accompanied by cardiovascular features such as hypotension and sinus bradycardia. Here, we report an unusual case of junctional bradycardia caused by ciguatera in the Caribbean; to our knowledge, the first such report from the region. An increase in global sea temperatures is predicted to lead to the spread of ciguatera beyond traditional endemic areas, and the globalisation of trade in coral reef fish has resulted in sporadic cases occurring in developed countries far away from endemic areas. This case serves as a reminder to consider environmental intoxications such as ciguatera within the differential diagnosis of bradycardias.

Emerging Marine Biotoxins in Seafood from European Coasts: Incidence and Analytical Challenges

The presence of emerging contaminants in food and the sources of the contamination are relevant issues in food safety. The impact of climate change on these contaminations is a topic widely debated; however, the consequences of climate change for the food system is not as deeply studied as other human and animal health and welfare issues. Projections of climate change in Europe have been evaluated through the EU Commission, and the impact on the marine environment is considered a priority issue. Marine biotoxins are produced by toxic microalgae and are natural contaminants of the marine environment. They are considered to be an important contaminant that needs to be evaluated. Their source is affected by oceanographic and environmental conditions; water temperature, sunlight, salinity, competing microorganisms, nutrients, and wind and current directions affect the growth and proliferation of microalgae. Although climate change should not be the only reason for this increase and other factors such as eutrophication, tourism, fishery activities, etc. could be considered, the influence of climate change has been observed through increased growth of dinoflagellates in areas where they have not been previously detected. An example of this is the recent emergence of ciguatera fish poisoning toxins, typically found in tropical or subtropical areas from the Pacific and Caribbean and in certain areas of the Atlantic Sea such as the Canary Islands (Spain) and Madeira (Portugal). In addition, the recent findings of the presence of tetrodotoxins, typically found in certain areas of the Pacific, are emerging in the EU and contaminating not only the fish species where these toxins had been found before but also bivalve mollusks. The emergence of these marine biotoxins in the EU is a reason for concern in the EU, and for this reason, the risk evaluation and characterization of these toxins are considered a priority for the European Food Safety Authorities (EFSA), which also emphasize the search for occurrence data using reliable and efficient analytical methods.

Fish Hybridization Leads to Uncertainty Regarding Ciguatera Fish Poisoning Risk; Confirmation of Hybridization and Ciguatoxin Accumulation with Implications for Stakeholders

Globally, ciguatera fish poisoning (CFP) avoidance efforts rely primarily on local knowledge of the fish being consumed, its collection location, and association with illnesses. In 2016, several fish that appeared to be hybrids between a local commercially prized species, Ocyurus chrysurus, and a regionally prohibited species Lutjanus apodus (due to CFP concerns), were caught nearshore in United States Virgin Islands waters, leading to confusion regarding the safety of consuming the fish. The hybrid status of the fish was verified as O. chrysurus (male) × L. apodus (female) by comparing two sets of gene sequences (mitochondrial CO1 and nuclear S7). Using an in vitro mouse neuroblastoma (N2a) assay, one of the hybrid fish exhibited a composite cytotoxicity of 0.038 ppb Caribbean ciguatoxin-1 (C-CTX-1) equivalents (Eq.); a concentration below the US Food and Drug Administration (FDA) guidance level for safety in fish products for CFP (0.1 ppb C-CTX-1 Eq.) but approximately 2× above the maximum described in the commercially prized parent species (0.019 ppb C-CTX-1 Eq./g). C-CTX-1 was confirmed in the hybrid sample by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The second hybrid fish tested negative for CTXs. This research confirms hybridization between two species with contrasting commercial statuses, discusses CTX accumulation implications for hybridization, and provides a methodology for future studies into novel CFP vectors, with the goal of providing critical information for fishermen and consumers regarding CFP risk management.

An Attempt to Characterize the Ciguatoxin Profile in Seriola fasciata Causing Ciguatera Fish Poisoning in Macaronesia

Ciguatera Fish Poisoning is a worldwide concern caused by the consumption of fish contaminated with ciguatoxins not only in endemic regions in the Pacific Ocean or the Caribbean Sea but also in emerging areas of Macaronesia on the eastern Atlantic. The recent emergence of these toxins in other coastal areas worldwide, prompted the need for the characterization of the risk in these areas. This Ciguatera Fish Poisoning risk has been recently identified as a potential threat in subtropical areas of the Atlantic coast and scientific efforts are being focused in the identification and confirmation of the toxins involved in this potential risk. Neuroblastoma cell assay has been widely used for the evaluation of the toxicity in several marine biotoxin groups, and found to be a very useful tool for toxicity screening. LC-MS/MS has been also used for confirmatory purposes although the main limitation of the advances on LC-MS/MS development is due to commercial unavailability of reference materials and hampers method implementation and validation or even confirmation of the ciguatoxins (CTXs) responsible for the toxic profiles. While neuroblastoma cell assay (N2a) is typically used for toxicity screening as mentioned above, being necessary to confirm this N2a toxicity by LC-MS/MS, this study is designed using N2a as a tool to confirm the toxicity of the fractions obtained corresponding to potential CTXs analogues according to the analysis by LC-MS/MS. With this aim, an amberjack sample (Seriola fasciata) from Selvagen Islads (Portugal) and implicated in Ciguatera Fish Poisoning was analyzed by LC-MS/MS and Caribbean Ciguatoxins were found to be mainly responsible for the toxicity. N2a was used in this work as a tool to help in the confirmation of the toxicity of fractions obtained by HPLC. Caribbean Ciguatoxin-1 was found as the main analogue responsible for the N2a toxicity while three Caribbean Ciguatoxin-1 (C-CTX1) metabolites which contribute to the total toxicity were also identified.

Spatio-temporal dynamics and biotic substrate preferences of benthic dinoflagellates in the Lesser Antilles, Caribbean sea

Epibenthic dinoflagellates were monitored monthly over an 18 month period in Guadeloupe and Martinique (Lesser Antilles, Caribbean Sea). These islands are located in the second most affected ciguatera fish poisoning (CFP) region of the world. Guadeloupe presented five times more total epibenthic dinoflagellates and two times less abundant Gambierdiscus spp. compared to Martinique, although the area of frequent CFP outbreaks covers Guadeloupe and not Martinique. Results did not show any clear seasonal variations of benthic dinoflagellates abundances. Temperature and salinity were not driving parameters in the evolution of total benthic dinoflagellate abundances. Preferential associations were found between macrophyte species and epibenthic dinoflagellates. The Phaeophyceae Dictyota spp. hosted the highest abundances of total epibenthic dinoflagellates, composed mainly of Ostrepsis and Prorocentrum genera. The seagrass Halophila stipulacea hosted the highest abundances of Gambierdiscus spp. and Sinophysis spp. whilst the highest abundance of Coolia was determined on Galaxaura spp. The pelagic Sargassum spp. hosted the lowest abundances of benthic dinoflagellates including the genus Gambierdiscus.

Ciguatera in Mexico (1984⁻2013)

Historical records of ciguatera in Mexico date back to 1862. This review, including references and epidemiological reports, documents 464 cases during 25 events from 1984 to 2013: 240 (51.72%) in Baja California Sur, 163 (35.12%) in Quintana Roo, 45 (9.69%) in Yucatan, and 16 (3.44%) cases of Mexican tourists intoxicated in Cuba. Carnivorous fish, such as snapper (Lutjanus) and grouper (Epinephelus and Mycteroperca) in the Pacific Ocean, and great barracuda (Sphyraena barracuda) and snapper (Lutjanus) in the Atlantic (Gulf of Mexico and Caribbean Sea), were involved in all cases. In the Mexican Caribbean, a sub-record of ciguatera cases that occurred before 1984 exists. However, the number of intoxications has increased in recent years, and this food poisoning is poorly studied in the region. Current records suggest that ciguatera fish poisoning in humans is the second most prevalent form of seafood poisoning in Mexico, only exceeded by paralytic shellfish poisoning (505 cases, 21 fatalities in the same 34-year period). In this study, the status of ciguatera in Mexico (epidemiological and treatment), and the fish vectors are reviewed. Dinoflagellate species Gambierdiscus, Ostreopsis, and Prorocentrum are related with the reported outbreaks, marine toxins, ecological risk, and the potential toxicological impact.

New Insights into the Occurrence and Toxin Profile of Ciguatoxins in Selvagens Islands (Madeira, Portugal)

Ciguatoxins (CTXs), endemic from tropical and subtropical regions of the Pacific and Indian Ocean and the Caribbean Sea, have caused several human poisonings during the last decade in Europe. Ciguatera fish poisonings (CFP) in Madeira and Canary Islands appear to be particularly related with consumption of fish caught close to Selvagens Islands, a Portuguese natural reserve composed of three small islands that harbor high fish biomass. In this study, fish specimens considered as potential vectors of CTXs were caught in Madeira and Selvagens archipelagos for toxins determination via sensitive liquid chromatography with tandem mass spectrometry detection (LC⁻MS/MS). CTXs were found in most of the fish samples from Selvagens and none from Madeira. Caribbean ciguatoxin-1 (C-CTX1) was the only toxin congener determined, reaching the highest value of 0.25 µg C-CTX1 kg-1 in a 4.6 kg island grouper (Mycteroperca fusca). This study indicates that a diversity of fish from different trophic levels contains CTXs, Selvagens appear to be one of the most favorable locations for CTXs food web transfer and finally, this study highlights the need of further research based on intensive environmental and biological sampling on these remote islands.

Taxonomy and toxin production of Gambierdiscus carpenteri (Dinophyceae) in a tropical marine ecosystem: The first record from the Philippines

Morphological and phylogenetic analysis showed that the Gambierdiscus isolate from Bolinao, Philippines belongs to the species of G. carpenteri. It was morphologically more similar to the Merimbula strain than the subtropical Florida Keys strain. Growth and toxin production were also investigated at varying levels of temperature, salinity, and irradiance. Gambierdiscus are known to grow favorably in a low light environment. However, this study showed high growth rates of G. carpenteri even at high irradiance levels. Generally, cells produced more toxins at lower treatment levels. Highest cellular toxin content recorded was 7.48 ± 0.49 pg Pbtx eq/cell at culture conditions of 25 °C, 100 μmol photons m^-2 s^-1, and salinity of 26. Growth rate and toxin production data suggest that cells produced more toxins during the slowest growth at certain range of treatments. This information gives insight into how changes in environmental conditions may affect toxin production and growth of G. carpenteri.

Consumption of barracuda in the Caribbean Sea linked to ciguatera fish poisoning among Filipino seafarers

Introduction

Ciguatera fish poisoning (CFP) is common in tropical and subtropical waters. On 13 November 2015, eight Filipino seafarers from a cargo ship sailing in the Caribbean Sea experienced a range of symptoms after consuming a barracuda. Upon their return to the Philippines, an investigation was conducted to describe the cases.

Methods

A case-series was conducted. A CFP case was defined as a previously well individual on the ship who developed at least one gastrointestinal symptom and at least one neurologic manifestation after eating barracuda on 13 November 2015. All cases were admitted to hospital in Manila, Philippines and were interviewed using a standard questionnaire. Urine and serum samples of cases were collected for ciguatoxin (CTX) testing by radiological and receptor-binding assay.

Results

Eight of the 25 seafarers on the ship ate the barracuda; all eight met the CFP case definition. The age of cases ranged from 37 to 58 years (median: 47 years) and all were males. Onset of symptoms ranged from 1 to 3 hours (median: 2 hours) from the time of ingestion of the barracuda. All cases experienced gastrointestinal (nausea, vomiting, diarrhoea) and neurologic (temperature allodynia, itchiness) symptoms but no cardiovascular manifestations. Urine and serum specimens of all eight cases showed CTX below the detection limit.

Discussion

The Philippines Epidemiology Bureau recommended that the Philippine Maritime Authority include CTX poisoning and its health risks in seafarers’ training to prevent future cases of CFP. The Event-based Surveillance and Response system will continue to provide a mechanism for the reporting and appropriate management of CFP cases.

Incidence and clinical characteristics of ciguatera fish poisoning in Guadeloupe (French West Indies) between 2013 and 2016: a retrospective cases-series

This retrospective case study analysed the incidence and symptoms of ciguatera fish poisoning (ciguatera) in Guadeloupe (French West Indies) between 2013 and 2016. Cases attending the emergency departments of the two public hospitals and the reports received by the regional health authority in charge of monitoring (ARS) were compiled. Two hundred and thirty-four cases of poisoning were observed, with a mean annual incidence of 1.47/10,000 (95% CI): 1.29-1.66), i.e 5 times higher than the previously reported incidence (1996-2006). The main species described as being responsible for poisoning were fish from the Carangidae family (n = 47) (jack), followed by fish from the Lutjanidae family (n = 27) (snapper), Serranidae family (n = 15) (grouper), Sphyraenidae family (n = 12) (barracuda), and Mullidae family (n = 12) (goatfish). One case of lionfish ciguatera was observed. 93.9% of patients experienced gastrointestinal symptoms, 76.0% presented neurological signs (mainly paresthesia, dysesthesia and pruritus) and 40.3% presented cardiovascular symptoms (bradycardia and/or hypotension). A high frequency (61.4%) of hypothermia (body temperature <36.5 °C) was observed. This study reports for the first time the relatively high frequency of cardiac symptoms and low body temperature. The monitoring of ciguatera poisoning throughout the Caribbean region must be improved, notably after reef disturbance due to Irma and Maria major cyclones.

Ciguatera poisoning in the Cook Islands

This case report presents two British medical students who contracted ciguatera poisoning while on elective in the Cook Islands. Thirty-six hours after consuming two reef fish they developed paraesthesia of the mouth, hands and feet, myalgia, pruritis and cold allodynia. Neurological examination was normal. Diagnosis of ciguatera poisoning was made on history of reef fish consumption and classical clinical presentation. Management was symptomatic (antihistamines) and both students made a full recovery within 10 weeks.

Evaluation of seafood toxicity in the Australes archipelago (French Polynesia) using the neuroblastoma cell-based assay

Ciguatera fish poisoning (CFP), a disease caused by consuming fish that have accumulated ciguatoxins (CTXs) in their tissue, is regarded as the most prevalent form of intoxication in French Polynesia. Recently, the Australes, one of the least affected archipelago until the early 1980s, has shown a dramatic increase in its incidence rates in 2009 with unusual CFP cases. In the present work, potential health hazards associated with the proliferation of various marine phytoplankton species and the consumption of fish and marine invertebrates highly popular among local population were assessed in three Australes islands: Raivavae, Rurutu and Rapa. Extracts from the marine dinoflagellates Gambierdiscus, Ostreospis and mat-forming cyanobacteria as well as fish, giant clams and sea urchin samples were examined for the presence of CTXs and palytoxin (PLTX) by using the neuroblastoma cell-based assay (CBA-N2a). Cytotoxic responses observed with both standards (Pacific CTX-3C and PLTX) and targeted marine products indicate that CBA-N2a is a robust screening tool, with high sensitivity and good repeatability and reproducibility. In Rurutu and Raivavae islands, our main findings concern the presence of CTX-like compounds in giant clams and sea urchins, suggesting a second bio-accumulation route for CFP toxins in the ciguatera food chain. In Rapa, the potential CFP risk from Gambierdiscus bloom and fish was confirmed for the first time, with levels of CTXs found above the consumer advisory level of 0.01 ng Pacific CTX-1B g(-1) of flesh in three fish samples. However, despite the presence of trace level of PLTX in Ostreopsis natural assemblages of Rapa, no sign of PLTX accumulation is yet observed in tested fish samples. Because this multi-toxinic context is likely to emerge in most French Polynesian islands, CBA-N2a shows great potential for future applications in the algal- and toxin-based field monitoring programmes currently on hand locally.

Update on methodologies available for ciguatoxin determination: perspectives to confront the onset of ciguatera fish poisoning in Europe

Ciguatera fish poisoning (CFP) occurs mainly when humans ingest finfish contaminated with ciguatoxins (CTXs). The complexity and variability of such toxins have made it difficult to develop reliable methods to routinely monitor CFP with specificity and sensitivity. This review aims to describe the methodologies available for CTX detection, including those based on the toxicological, biochemical, chemical, and pharmaceutical properties of CTXs. Selecting any of these methodological approaches for routine monitoring of ciguatera may be dependent upon the applicability of the method. However, identifying a reference validation method for CTXs is a critical and urgent issue, and is dependent upon the availability of certified CTX standards and the coordinated action of laboratories. Reports of CFP cases in European hospitals have been described in several countries, and are mostly due to travel to CFP endemic areas. Additionally, the recent detection of the CTX-producing tropical genus Gambierdiscus in the eastern Atlantic Ocean of the northern hemisphere and in the Mediterranean Sea, as well as the confirmation of CFP in the Canary Islands and possibly in Madeira, constitute other reasons to study the onset of CFP in Europe [1]. The question of the possible contribution of climate change to the distribution of toxin-producing microalgae and ciguateric fish is raised. The impact of ciguatera onset on European Union (EU) policies will be discussed with respect to EU regulations on marine toxins in seafood. Critical analysis and availability of methodologies for CTX determination is required for a rapid response to suspected CFP cases and to conduct sound CFP risk analysis.

Emergence of Imported Ciguatera in Europe: Report of 18 Cases at the Poison Control Centre of Marseille

BACKGROUND

Ciguatera is a disease caused by the ingestion of fish containing the toxins of Gambierdiscus toxicus. This dinoflagellate is frequently found in damaged coral reef systems. Previously rare in Europe, this disease entity is now seen in tourists returning from tropical countries.

CASE SERIES

Eighteen patients were examined between 1997 and 2002. Nine poisonings occurred in Atlantic Ocean islands, eight in Pacific Ocean islands, and one in the Egyptian Red Sea coast. Gastrointestinal signs were always present in the Atlantic areas, but were less severe or absent in the Pacific areas. All patients had sensory disturbances, and two of them had motor disturbances affecting the respiratory muscles and leading to the death of a 73-year-old man in Cuba. The 17 surviving patients returned to France and for 2 to 18 months suffered from arthralgias, myalgias, or pruritus.

CONCLUSION

Ciguatera is a newly imported intoxication in Europe. As the number of international tourists grows each year, this type of poisoning will be seen more frequently. Furthermore, as the condition of coral reefs declines around the world and the prevalence of G. toxicus increases, physicians in non-tropical countries should be prepared to manage such poisoned patients.

Pacific ciguatoxin-1b effect over Na+ and K+ currents, inositol 1,4,5-triphosphate content and intracellular Ca2+ signals in cultured rat myotubes

1. The action of the main ciguatoxin involved in ciguatera fish poisoning in the Pacific region (P-CTX-1b) was studied in myotubes originated from rat skeletal muscle cells kept in primary culture. 2. The effect of P-CTX-1b on sodium currents at short times of exposure (up to 1 min) showed a moderate increase in peak Na+ current. During prolonged exposures, P-CTX-1b decreased the peak Na+ current. This action was always accompanied by an increase of leakage currents, tail currents and outward Na+ currents, resulting in an intracellular Na+ accumulation. This effect is blocked by prior exposure to tetrodotoxin (TTX) and becomes evident only after washout of TTX. 3. Low to moderate concentrations of P-CTX-1b (2-5 nM) partially blocked potassium currents in a manner that was dependent on the membrane potential. 4. P-CTX-1b (2-12 nM) caused a small membrane depolarization (3-5 mV) and an increase in the frequency of spontaneous action potential discharges that reached in general low frequencies (0.1-0.5 Hz). 5. P-CTX-1b (10 nM) caused a transient increase of intracellular inositol 1,4,5-trisphosphate (IP(3)) mass levels, which was blocked by TTX. 6. In the presence of P-CTX-1b (10 nM) and in the absence of external Ca2+, the intracellular Ca2+ levels show a transient increase in the cytoplasm as well as in the nuclei. The time course of this effect may reflect the action of IP(3) over internal stores activated by P-CTX-1b-induced membrane depolarization.