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This study confirms the presence of the toxigenic benthic dinoflagellates Gambierdiscus belizeanus and Ostreopsis spp. in the central Red Sea. To our knowledge, this is also the first report of these taxa in coastal waters of Saudi Arabia, indicating the potential occurrence of ciguatera fish poisoning (CFP) in that region. During field investigations carried out in 2012 and 2013, a total of 100 Turbinaria and Halimeda macroalgae samples were collected from coral reefs off the Saudi Arabian coast and examined for the presence of Gambierdiscus and Ostreopsis, two toxigenic dinoflagellate genera commonly observed in coral reef communities around the world. Both Gambierdiscus and Ostreopsis spp. were observed at low densities (

Ciguatoxins (CTXs) are emerging marine neurotoxins representing the main cause of ciguatera fish poisoning, an intoxication syndrome which configures a health emergency and constitutes an evolving issue constantly changing due to new vectors and derivatives of CTXs, as well as their presence in new non-endemic areas. The study applied the neuroblastoma cell model of human origin (SH-SY5Y) to evaluate species-specific mechanistic information on CTX toxicity. Metabolic functionality, cell morphology, cytosolic Ca2+i responses, neuronal cell growth and proliferation were assessed after short- (4-24h) and long-term exposure (10days) to P-CTX-3C. In SH-SY5Y, P-CTX-3C displayed a powerful cytotoxicity requiring the presence of both Veratridine and Ouabain. SH-SY5Y were very sensitive to Ouabain: 10 and 0.25nM appeared the optimal concentrations, for short- and long-term toxicity studies, respectively, to be used in co-incubation with Veratridine (25μM), simulating the physiological and pathological endogenous Ouabain levels in humans. P-CTX-3C cytotoxic effect, on human neurons co-incubated with OV (Ouabain+Veratridine) mix, was expressed starting from 100pM after short- and 25pM after long-term exposure. Notably, P-CTX-3C alone at 25nM induced cytotoxicity after 24h and prolonged exposure. This human brain-derived cell line appears a suitable cell-based-model to evaluate cytotoxicity of CTX present in marine food contaminated at low toxic levels and to characterize the toxicological profile of other/new congeners.

Ciguatera fish poisoning arises primarily from consumption of carnivorous reef fish caught in tropical and sub-tropical waters. Ciguatoxins, a class of tasteless, heat-stable, polycyclic toxins produced by dinoflagellates, accumulate through the food chain and concentrate in various carnivorous fish, such as groupers, barracudas, wrasses, amberjack, kingfishes, and eels. Characteristics of ciguatera fish poisoning include early nausea, vomiting, and diarrhea in the first one to two days post ingestion, followed by the appearance of sensory disturbances. The classic dysaesthesia is cold allodynia, often described as reversal of hot and cold sensation, but a more accurate description is burning pain on exposure to cold.To discuss and appraise the evidence regarding the use of mannitol or other drugs in treating ciguatera framed in the historical context of the last four decades.We searched PubMed and Embase for all years from 1966 to March 31, 2017 with search terms "ciguatera", "mannitol", and "treatment". These searches identified 85 articles, of which 36 were relevant to the review question. We searched Google Scholar to supplement the primary search and reviewed the references of articles for sources overlooked in the original searches. These secondary searches identified another 23 references. We excluded six clinical reports (two case series and four case reports) which did not clearly describe ciguatera or which lacked information on treatment or outcome. Fifty-three clinical articles remained for review. We searched PubMed using "ciguatera" AND "treatment" NOT "mannitol" to better identify reports describing other treatments. The search identified 128 articles, of which nine described specific pharmacological treatments and their outcomes. We combined our findings into a consensus review of the evidence both for and against the use of mannitol or other medications for ciguatera fish poisoning. Early human evidence of effectiveness of mannitol: A 1988 report described an unexpected discovery that intravenous mannitol could rapidly and effectively treat ciguatera fish poisoning. Several other uncontrolled case series and case reports appeared to support the use of mannitol. In 2002, a small randomized, controlled trial reported no significant difference between mannitol and normal saline. Subsequent case reports have cited this study as the reason for or to withhold mannitol. Thus, some controversy exists regarding whether mannitol is useful or not for treating ciguatera fish poisoning. Basic science and animal research on ciguatera and mannitol: In vitro experiments of isolated neurons demonstrate that ciguatoxins produce neuronal edema, open certain sodium channels, block potassium channels, cause uncontrolled and repetitive action potentials after a stimulus. Addition of mannitol decreases the edema and reduces the uncommanded action potentials. However, intraperitoneal injection of ciguatoxin in rats increases neuronal refractory period and slows nerve conduction velocity. Treatment with mannitol fails to correct these effects. Comparative trials of mannitol: Evidence supporting mannitol for ciguatera fish poisoning includes four uncontrolled case series, one prospective, unblinded comparative trial and several case reports. Evidence against mannitol consists of one RCT, which has a small sample size and several potential limitations. Empirical human experience with other treatments: Evidence regarding other treatments consists only of ten case reports and three overlapping case series that describe using amitriptyline, fluoxetine, duloxetine, gabapentin, pregabalin, or tocainide. For each of these, a long duration of treatment appears to be necessary to maintain symptomatic improvement. None of these treatments has been shown to be superior to mannitol.It is reasonable to consider using intravenous mannitol in cases of acute ciguatera fish poisoning. Medications used in other neuropathic syndromes appear to suppress the paresthesiae of persistent ciguatera cases. However, the human evidence is of low quality for all treatments.

First report of the genus Gambierdiscus (Dinophyceae) and other benthic dinoflagellates from Isla del Coco National Park, Costa Rica, Eastern Tropical Pacific. The Eastern Tropical Pacific is a region reported as free of ciguatera poisoning that causes serious gastrointestinal, neural and cardiovascular problems, even death. But with this study we found a high incidence of benthic microalgae involved in ciguatera poisoning in Isla del Coco National Park (PNIC, from its name in Spanish), Costa Rica. Between 2006 and 2011, during expeditions to PNIC, 420 phytoplankton samples with the interest of finding benthic dinoflagellates involved in the ciguatera poisoning were collected and analyzed. Samples were taken with phytoplankton nets, towed vertically and horizontally or carried by diving, between 5 to 30 m depth, over reef areas, and by direct extraction from benthic macroalgae. We found the dinoflagellates Gambierdiscus spp., Coolia tropicalis, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae and Ostreopsis siamensis. The quantity of dinoflagellates by macroalgae weight was high, mainly for Gambierdiscus. Ostreopsis and Prorocentrum, the most widely distributed genera throughout the collection sites. Gambierdiscus is a ciguatera producing genus. Two different sizes of Gambierdiscus were found, and comparing our samples with other studies, we conclude that they are different to any previously reported. They possibly represent two new species. Coco Island is an oceanic island and because of its protection status, it is an ideal site for studying the evolution of marine phytoplankton. Also, long-term monitoring is important due to the variety of potentially toxic dinoflagellates living in this marine ecosystem. This is the first study to report benthic dinoflagellates implicated in ciguatera poisoning in other areas of the Eastern Tropical Pacific. Citation: Vargas-Montero, M., Á. MoralesRamírez & J. Cortés. 2012. Primer informe del género Gambierdiscus (Dinophyceae) en el Parque Nacional Isla del Coco, Pacífico Tropical Oriental. Rev. Biol. Trop. 60 (Suppl. 3): 187-199. Epub 2012 Dec 01. El Pacífico Tropical Oriental se ha indicado como una región de los océanos libre de ciguatera, una intoxicación que causa serios trastornos gastrointestinales, neurológicos y cardiovasculares, en casos extremos, la muerte. Pero con el presente estudio hemos encontrado una incidencia alta de microalgas bénticas involucradas en la producción de ciguatera en el Parque Nacional Isla del Coco (PNIC), Costa Rica. En campañas oceanográficas realizadas entre el 2006 y el 2011 al PNIC se recolectaron 420 muestras de fitoplancton con el interés de encontrar especies de dinoflagelados bentónicos implicados en la producción de ciguatera. Las muestras se tomaron con red de fitoplancton o mediante buceos, entre los 5 y 30 m de profundidad en zonas de arrecife y por extracción directa de macroalgas. Se encontró a los dinoflagelados Gambierdiscus spp., Coolia tropicales, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae y Ostreopsis siamensis. Se determinó que la cantidad de dinoflagelados por peso de macroalga era elevada, principalmente para el género Gambierdiscus. Los géneros Ostreopsis y Prorocentrum mostraron tener la mayor distribución en los sitios de colecta. Gambierdiscus es un género productor de ciguatera. Se encontraron dos tamaños diferentes de individuos de Gambierdiscus, Comparando los especímenes de Gambierdiscus encontradas con otros estudios, se concluye que son diferentes a las descritas anteriormente, por lo que podría tratarse de especies nuevas, lo que se confirmará con cultivos y análisis moleculares. Al ser la Isla del Coco un sitio oceánico aislado y en estado de conservación, es un sitio ideal para el estudio de la evolución de especies de fitoplancton marino. Además, el monitoreo a largo plazo es muy importante debido a la variedad de dinoflagelados bentónicos potencialmente tóxicos que habitan en este ecosistema marino. Este es el primer estudio donde se da a conocer la incidencia de dinoflagelados bentónicos implicados en ciguatera para el Pacífico Tropical Oriental.

Species in the epi-benthic dinoflagellate genus Gambierdiscus produce ciguatoxins (CTXs) and maitotoxins (MTXs), which are among the most potent marine toxins known. Consumption of fish contaminated with sufficient quantities of CTXs causes Ciguatera Fish Poisoning (CFP), the largest cause of non-bacterial food poisoning worldwide. Maitotoxins, which can be found in the digestive system of fish, could also contribute to CFP if such tissues are consumed. Recently, an increasing number of Gambierdiscus species have been identified; yet, little is known about the variation in toxicity among Gambierdiscus strains or species. This study is the first assessment of relative CTX- and MTX-toxicity of Gambierdiscus species from areas as widespread as the North-Eastern Atlantic Ocean, Pacific Ocean and the Mediterranean Sea. A total of 13 strains were screened: (i) seven Pacific strains of G. australes , G. balechii , G. caribaeus , G. carpenteri , G. pacificus , G. scabrosus and one strain of an undetermined species ( Gambierdiscus sp. Viet Nam), (ii) five strains from the North-Eastern Atlantic Ocean (two G. australes , a single G. excentricus and two G. silvae strains), and (iii) one G. carolinianus strain from the Mediterranean Sea. Cell pellets of Gambierdiscus were extracted with methanol and the crude extracts partitioned into a CTX-containing dichloromethane fraction and a MTX-containing aqueous methanol fraction. CTX-toxicity was estimated using the neuro-2a cytoxicity assay, and MTX-toxicity via a human erythrocyte lysis assay. Different species were grouped into different ratios of CTX- and MTX-toxicity, however, the ratio was not related to the geographical origin of species (Atlantic, Mediterranean, Pacific). All strains showed MTX-toxicity, ranging from 1.5 to 86 pg MTX equivalents (eq) cell −1 . All but one of the strains showed relatively low CTX-toxicity ranging from 0.6 to 50 fg CTX3C eq cell −1 . The exception was the highly toxic G. excentricus strain from the Canary Islands, which produced 1426 fg CTX3C eq cell −1 . As was true for CTX, the highest MTX-toxicity was also found in G. excentricus . Thus, the present study confirmed that at least one species from the Atlantic Ocean demonstrates similar toxicity as the most toxic strains from the Pacific, even if the metabolites in fish have so far been shown to be more toxic in the Pacific Ocean.

Purpose: The review is provoked because of lack of awareness of the medical practitioners in Bulgaria concerning of the ethnology, pathogenesis, clinical symptoms and treatment of the ciguatera fish poisoning (CFP). This can be a source of prolonged diagnostic delays, as some cases reporting in another country in Europe, for example Germany, Spain and UK. Varna is the sea town with many sailor crews returning from tropical and subtropical regions, or CFP can affect people who travel to the Pacific and Caribbean or ate exotic fish from supermarket. The information of this fish food-borne poisoning is part of student’s education in discipline “Marine medicine” in Medical University, Varna. Materials and methods: To present better information from different authors and last scientific data, we made review of published materials of 58 issues to construct definition, history, etiology, pathogenesis (toxins and mechanisms of action), clinical symptoms, treatment and prevention of the Ciguatera or ichtyosarcotoxicosis, a wide spread food-born poisoning. Results: Ciguatera poisoning is ichtyosarcotoxicosis, a wide-spread foodborne poisoning in people after consumption of flesh of different kinds of fishes in which toxins produced by poisonous microorganisms (Dinoflagellates) have accumulated. The poisoning develops by accumulating toxins higher up the food chain starting with toxin producing dinoflagellates (species: Gambierdiscus toxicus, Prorocentrum concavum, Pr. lima, Ostreoposis lenticularis, Ostr. Siamensis and others), continuing with the poisoned algae (species: Portieria, Halymenia, Turbinaria, Sargassum), and after that involving small crustacea and small fishes to greater fishes (vector fishes, genus Herbivores and Carnivores), in which the toxins have been stored in amount, great enough to cause foodborne poisoning in humans. This poisoning is widespread in tropical and subtropical regions, but because of its delayed toxic effects, lasting for months and years, there is a possibility that every medic can encounter its unusual symptoms, requiring specific treatment. The following toxins cause the poisoning: ciguatoxin, meitotoxin, ostreotoxin, domoic acid and some other unspecified toxins. They are lipid soluble, thermo stable and cannot be decomposed by culinary processing. These toxins have neurotoxic, cardiotoxic, hemolytic properties and cause diarrheic syndrome. Clinical presentation is characterized by average latent period of 12 hours after the consummation, vomiting and diarrhea next 24 hours and neurological symptoms that appear at the beginning of the poisoning with paresthesias along the body, changing feeling of hot and cold, strong myalgia. Disturbances in cardiac rhythm and conduction, strong dehydration or shock are possible in severe cases. Light cases pass over in several days, but, more often the poisoning has a chronic course – from 3-4 months to 1 year, with prevalence of neurologic symptoms: myalgia, paresthesias, skin itching with scratches, depression. The management is not specific and includes stomach lavage with activated charcoal, fluids replacement during the first 24 hours, corticosteroids, antiallergics, high doses of vitamins from group B (Vit. B1, Vit. B6, Vit. B12), mannitol IV, nootropic medicaments, antidepressants and other symptomatic medicaments. The prophylaxis is done by examining every fish with specific test for detecting ciguateratoxin.

© 2016 Elsevier B.V. Ciguatera fish poisoning (CFP) has been reported for many years in Rarotonga, Cook Islands, and has had the world's highest reported incidence of this illness for the last 20 years. Following intensive sampling to understand the distribution of the causative organisms of CFP, an undescribed Gambierdiscus species was isolated from the Rarotongan lagoon. Gambierdiscus cheloniae sp. nov. has the common Gambierdiscus Kofoidian plate formula (except for a variability in the number of precingular plates in aberrant cells): Po, 3′, 6″ (7″), 6C?, 6 or 7S, 5′″, 1p and 2″″. The 2′ plate is hatchet shaped and the dorsal end of 1p is pointed and the relatively narrow 1p plate. Morphologically G. cheloniae is similar to the genetically closely related species G. pacificus, G. toxicus and G. belizeanus, although smaller (depth and length) than G. toxicus. The apical pore plate varies from those of G. belizeanus and G. pacificus, which are shorter and narrower, and from G. toxicus, which is larger. G. cheloniae also differs from G. pacificus in the shape of the 2′ plate. The description of this new species is supported by phylogenetic analyses using three different gene regions. G. cheloniae produced the putative maitotoxin-3 analogue, MTX-3, but neither maitotoxin or monitored ciguatoxin. Extracts of G. cheloniae were shown to be highly toxic to mice by intraperitoneal (i.p.) injection, although they were less toxic by gavage. It is possible that this species produces toxins other than putative MTX-3.

International audience; Ciguatera Fish Poisoning (CFP) is a non-bacterial seafood poisoning well characterized in the remote archipelagos of French Polynesia, yet poorly documented in the Society archipelago, most notably on Moorea, the second most populated island in French Polynesia, which counts a high proportion of fishermen fishing on a regular basis. To address this knowledge gap, a holistic study of the ciguatera issue was conducted on Moorea. First, ciguatera risk was analysed in terms of incidence rate, fish species most commonly involved and risk stratification in Moorea lagoon based on 2007–2013 epidemiological data. A mean incidence rate of 8 cases per 10,000 inhabitants for the study period and an average under-reporting rate of 54% were found. Taking into account hospitalization and medication fees, and loss of productive days, the health-related costs due to CFP were estimated to be USD $1613 and $749 for each reported and unreported case, respectively, with an overall cost of USD $241,847 for the study period. Comparison of the present status of CFP on Moorea with a risk map established in the late 1970’s showed that the spatial distribution of the risk has stayed relatively stable in time, with the north shore of the island remaining the most prone to ciguatera. Evaluation of the current knowledge on CFP among different populations groups, i.e. fishermen, residents and visitors, was also conducted through direct and indirect interviews. About half of the fishermen interviewed were actually able to identify risky fishing areas. While, overall, the CFP risk perception in the fishing community of Moorea seemed accurate, although not scientifically complete, it was sufficient for the safe practice of their fishing activities. This may be due in part to adaptive responses adopted by 36% of the fishermen interviewed, such as the avoidance of either high-risk fishing sites or toxic species. At the residents and visitors’ level, the study points out a striking lack of awareness of the CFP issue among visitors, as compared to local residents. Indeed, less than 25% of Moorea visitors vs. an average of 98% in residents were aware of CFP or of its presence on the island. Interestingly, evaluation of the fish consumption preferences showed that 70% of visitors do not consume lagoon fish during their stay, not for fear of CFP, but mainly due to the lack of availability of these species in recreational facilities or because they have nutritional preference for pelagic fish. This lack of awareness, along with the report by several CFP patients of the consumption of fish species yet banned for sale, stress the need for improved communication efforts on this critical issue among both residents and visitors on Moorea. The implementation of a public outreach strategy is proposed, based on both existing information networks and low-cost communication actions through information displays at various strategic locations, e.g. Tahiti-Faa’a international airport, the ferry boat station, recreational facilities, as well as the major trading points on Moorea Island.

Ciguatera fish poisoning is a frequently reported non-bacterial food-borne illness related to the consumption of seafood contaminated with ciguatoxins, and possibly maitotoxins. These toxins are synthesized by marine dinoflagellate species of Gambierdiscus and Fukuyoa genera, and their abundance is a matter of great concern due to their adverse effects to aquatic life and human health. The present study aims to assess the sensitivity of rat cardiomyoblast H9c2(2−1) cells to Gambierdiscus toxic compounds using concentration- and time-dependent sulforhodamine B (SRB) colorimetric assays. Low concentrations of Gambierdiscus extracts (corresponding to 1.3–2.3 cells mL−1) induced a concentration-dependent response. Specificity in time-dependent response of H9c2(2−1) cells was demonstrated for G. excentricus after a 180 min exposure compared to both G. cf. belizeanus and G. silvae species, with EC50s obtained after 720 and 360 min, respectively. The sensitivity of H9c2(2−1) cells to dinoflagellate toxic compounds was also tested with other genera from benthic (Coolia malayensis, Ostreopsis cf. ovata, Prorocentrum hoffmannianum and P. lima) and planktonic (Amphidinium carterae and Lingulodinium polyedrum) habitats. Amphidinium, Coolia and Lingulodinium data did not present any concentration-response relationships, and EC50 values could only be obtained after 720 and 1440 min of exposure to both Prorocentrum species and O. cf. ovata, respectively. This study demonstrated that the H9c2(2−1) SRB assay represents a promising and sensitive tool for the detection of Gambierdiscus toxic compounds present in water samples, particularly of G. excentricus at very low cell abundances.

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. SNMB-INOV: Innovation for a more competitive shellfish sector Operational Program Mar 2020, Portugal 2020 project Cigua - Portuguese Foundation for Science and Technology (FCT) [PTDC/CTA-AMB/30557/2017] FEDEREuropean Commission FCTPortuguese Foundation for Science and TechnologyEuropean Commission [UID/Multi/04326/2019] info:eu-repo/semantics/publishedVersion

This case report presents a four-year-old Danish girl, who acquired ciguatera fish poisoning after eating a meal containing fish while being on vacation in Cuba. After returning to Denmark, her main complaint was pain in her lower legs and disrupted sleep. She was seen by her primary care physicians and at a paediatric department but was not diagnosed, until a specialist in tropical diseases saw her seven months after her return from Cuba. She was successfully treated with amitriptyline and dietary changes.

Ciguatera is a non-bacterial seafood poisoning highly prevalent in French Polynesia where it constitutes a major health issue and a major threat to food sustainability and food security for local populations. Ciguatera results from the bioaccumulation in marine food webs of toxins known as ciguatoxins, originating from benthic dinoflagellates in the genera Gambierdiscus and Fukuyoa. Ciguatera is characterized by a complex array of gastrointestinal, neurological and cardiovascular symptoms. The effective management of patients is significantly hampered by the occurrence of atypical forms and/or chronic sequelae in some patients, and the lack of both a confirmatory diagnosis test and a specific antidote. In addition, recent findings have outlined the implication of novel species of the causative organisms as well as new vectors, namely marine invertebrates, in ciguatera outbreaks. Another novel trend relates to the geographical expansion of this disease to previously unaffected areas, not only in certain island groups of French Polynesia but also in temperate regions worldwide, as a likely consequence of the effects of climate change. Keywords: Ciguatoxins, ciguatera poisoning, Gambierdiscus, geographical expansion, marine invertebrates, new vectors, symptoms

The marine benthic dinoflagellate genus Gambierdiscus currently contains ~ 16 species that can be highly morphologically similar to one another, and therefore molecular genetic characterization is necessary to complement the morphological species determination. Gambierdiscus species can produce ciguatoxins, which can accumulate through the food chain and cause ciguatera fish poisoning. Recent studies have suggested that Gambierdiscus excentricus may be one of the main species responsible for ciguatoxin production in the temperate and tropical regions of the eastern Atlantic. The present study definitively identifies the species, G. excentricus, from Madeira Island, Northeast-Atlantic Ocean (32° 38′ N 16° 56′ W) by examining the morphology of a strain using light and scanning electron microscopy and sequencing regions of the ribosomal DNA (D8-D10 LSU, SSU rDNA). Variability in the shape of the apical pore and the microarchitecture of the apical pore plate were documented for the first time, as well as variability in the width of the second antapical plate. The first SSU rDNA sequence for the species is reported. Because G. excentricus is known to produce high levels of CTX-like compounds, its presence and toxicity should be regularly monitored to establish whether it is the primary cause of the ciguatera poisoning events on Madeira Island.

Dinoflagellates belonging to the genus Gambierdiscus produce ciguatoxins (CTXs), which are metabolized in fish to more toxic forms and subsequently cause ciguatera fish poisoning (CFP) in humans. Five species of Gambierdiscus have been described from the Canary Islands, where CTXs in fish have been reported since 2004. Here we present new data on the distribution of Gambierdiscus species in the Canary archipelago and specifically from two islands, La Palma and La Gomera, where the genus had not been previously reported. Gambierdiscus spp. concentrations were low, with maxima of 88 and 29 cells·g−1 wet weight in samples from La Gomera and La Palma, respectively. Molecular analysis (LSUrRNA gene sequences) revealed differences in the species distribution between the two islands: only G. excentricus was detected at La Palma whereas four species, G. australes, G. caribaeus, G. carolinianus, and G. excentricus, were identified from La Gomera. Morphometric analyses of cultured cells of the five Canary Islands species and of field specimens from La Gomera included cell size and a characterization of three thecal arrangement traits: (1) the shape of the 2′ plate, (2) the position of Po in the anterior suture of the 2′ plate, and (3) the length–width relationship of the 2″″ plate. Despite the wide morphological variability within the culture and field samples, the use of two or more variables allowed the discrimination of two species in the La Gomera samples: G. cf. excentricus and G. cf. silvae. A comparison of the molecular data with the morphologically based classification demonstrated important coincidences, such as the dominance of G. excentricus, but also differences in the species composition of Gambierdiscus, as G. caribaeus was detected in the study area only by using molecular methods.

Few studies have been carried out on benthic dinoflagellates along the Florida Keys, and little is known about their distribution or toxicity in Florida Bay. Here, the distribution and abundance of benthic dinoflagellates was explored in northern and eastern Florida Bay and along the bay and ocean sides of the Florida Keys. Isolates were brought into culture and their toxicity was tested with oyster larvae bioassays. Seven genera were detected, including Prorocentrum, Coolia, Ostreopsis, Amphidinium, Gambierdiscus, Fukuyoa (all included potentially toxic species) and Sinophysis. In general, distribution increased with water temperature and nutrient availability, especially that of phosphate. This study documented the first record of Coolia santacroce in the Florida Keys. Potential toxic effects of Gambierdiscus caribaeus, the abundance of which exceeded 1000 cells g−1 fw at some sites, were established using oyster larvae as a bioassay organism. These findings suggest a potential risk of ciguatera fish poisoning in this area.

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) &times, 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&times, 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.

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. info:eu-repo/semantics/publishedVersion

This research identifies factors associated with the contamination by ciguatoxins (CTXs) in a population of fish and proposes a predictive score of the presence of CTX-like toxicity in amberjack samples from the official control program of ciguatera in the Canary Islands of the Directorate-General (DG) Fisheries (Canary Government). Out of the 970 samples of fish studied, 177 (18.2%) samples showed CTX-like toxicity. The fish were classified according to the species, amberjack (Seriola dumerili and S. rivoliana) (n = 793), dusky grouper (Epinephelus marginatus) (n = 145) and wahoo (Acanthocybium solandri) (n = 32). The data were separated by species category and statistically examined, resulting in 137 (17.3%) amberjack and 39 (26.9%) grouper samples showing CTX-like toxicity; regarding wahoo species, only 1 toxic sample (3.1%) was found. According to fishing location the contamination rates suggested grouping the islands in four clusters; namely: {El Hierro: HI; La Gomera: LG; La Palma: LP}, {Gran Canaria: GC; Tenerife: TF}, {Fuerteventura: FU} and {Lanzarote: LZ}. For the amberjack species, the multivariate logistic regression showed the factors that maintained independent association with the outcome, which were the warm season (OR = 3.617; 95% CI = 1.249–10.474), the weight (per kg, 1.102; 95% CI = 1.069–1.136) and the island of fish catching. A prediction score was obtained for the probability of contamination by CTX in amberjack fish samples. The area under de curve (AUC) obtained using the validation data was 0.747 (95% CI = 0.662–0.833). Regarding grouper species, the island of fishing was the only factor that showed significant differences associated with the presence of CTX-like toxicity. We provide herein data for a better management and prediction of ciguatera in the Canary Islands, suggesting a review of the minimum limits of fish weight established by the Canary Government for the control program. info:eu-repo/semantics/acceptedVersion

This article discusses the epidemiology, prevention, clinical features, and treatment of venomous bites by snakes, lizards, and spiders; stings by fish, jellyfish, echinoderms, insects, and scorpions; and poisoning by ingestion of fish, turtles, and shellfish. Invertebrate stings cause fatalities by anaphylaxis, secondary to acquired hypersensitivity (Hymenoptera, such as bees, wasps, and ants; and jellyfish), and by direct envenoming (scorpions, spiders, jellyfish, and echinoderms). Simple preventive techniques, such as wearing protective clothing, using a flashlight at night, and excluding venomous animals from sleeping quarters, are of paramount importance to reduce the risk of venomous bites and stings.

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.

Ciguatera fish poisoning is an illness contracted through the ingestion of seafood containing ciguatoxins. It is prevalent in tropical regions worldwide, including in Australia. Ciguatoxins are produced by some species of Gambierdiscus. Therefore, screening of Gambierdiscus species identification through quantitative PCR (qPCR), along with the determination of species toxicity, can be useful in monitoring potential ciguatera risk in these regions. In Australia, the identity, distribution and abundance of ciguatoxin producing Gambierdiscus spp. is largely unknown. In this study we developed a rapid qPCR assay to quantify the presence and abundance of Gambierdiscus lapillus, a likely ciguatoxic species. We assessed the specificity and efficiency of the qPCR assay. The assay was tested on 25 environmental samples from the Heron Island reef in the southern Great Barrier Reef, a ciguatera endemic region, in triplicate to determine the presence and patchiness of these species across samples from Chnoospora sp., Padina sp. and Sargassum macroalgal hosts.Author’s summaryCiguatera fish poisoning is a human disease contracted by ingesting seafood contaminated with a group of neurotoxins. The group of neurotoxins, named ciguatoxins, are synthesised by species of single celled marine algae from the genus Gambierdiscus.Ciguatera fish poisoning occurs worldwide, particularly in tropical nations. Pacific Island nations are disproportionately impacted, and this impact is predicted to increase as the effects of climate change unfold. Few effective monitoring and mitigation strategies exist for ciguatera fish poisoning, and reporting rates of the disease are estimated to be approximately 20% at best. A global ciguatera strategy was developed by a group of researchers coordinated by UNESCO’s Intergovernmental Oceanographic Commission to characterise the cause and mode of action of ciguatera fish poisoning, as a matter of urgency.In this study, we designed a qPCR assay to detect a species of microalgae, Gambierdiscus lapillus. Gambierdiscus lapillus produces compounds with ciguatoxin-like properties, which may lead to ciguatoxin uptake in fish in the Australian region. This assay was sensitive and able to detect the presence of Gambierdiscus lapillus in a range of environmental samples from the Great Barrier Reef region, Australia.

Marine biotoxins accumulating in seafood products pose a risk to human health. These toxins are often potent in minute amounts and contained within complex matrices; requiring sensitive, reliable, and robust methods for their detection. The mouse neuroblastoma (Neuro-2a) cytotoxicity assay (N2a-assay) is a sensitive, high-throughput, in vitro method effective for detecting sodium channel-specific marine biotoxins. The N2a-assay can be conducted to distinguish between specific effects on voltage-gated sodium (NaV) channels, caused by toxins that activate (e.g., ciguatoxins (CTXs), brevetoxins (PbTxs)) or block (e.g., tetrodotoxins, saxitoxins) the target NaV. The sensitivity and specificity of the assay to compounds activating the NaV are achieved through the addition of the pharmaceuticals ouabain (O) and veratridine (V). However, these compounds can be toxic to Neuro-2a cells and their application at insufficient or excessive concentrations can reduce the effectiveness of this assay for marine toxin detection. Therefore, during growth incubation, Neuro-2a cells were exposed to O and V, and surviving cells exhibiting a lower sensitivity to O and V (OV-LS) were propagated. OV-LS Neuro-2a cells were selected for 60–80% survival when exposed to 0.22/0.022 mM O/V during the cytotoxicity assay. At these conditions, OV-LS N2a cells demonstrated a 3.5-fold higher survival rate 71% ± 7.9 SD (n = 232), and lower sensitivity to O/V, compared to the original Neuro-2a cells 20% ± 9.0 SD (n = 16). Additionally, OV-LS N2a cells were 1.3–2.6-fold more sensitive for detecting CTX3C 1.35 pg/ml, CTX1B 2.06 pg/ml, and PbTx-3 3.04 ng/ml compared to Neuro-2a cells using 0.1/0.01 mM O/V. Detection of CTX3C in a complex fish matrix using OV-LS cells was 0.0048 pg CTX3C/mg fish tissue equivalent. This work shows the potential for a significant improvement in sensitivity for CTX3C, CTX1B, and PbTx-3 using the OV-LS N2a-assay.

Anchored mesh screens have been suggested as a standardized approach to monitor the cell abundances of epiphytic dinoflagellates in benthic habitats, including toxigenic members of the Gambierdiscus genus responsible for ciguatera poisoning (CP). Here we deployed screens for 24h at eight sites in the Florida Keys and St. Thomas (US Virgin Islands) to evaluate their performance relative to the traditional method of assessing Gambierdiscus abundance in which cell counts are normalized to wet weight of host algae. The 30-month study (April 2013 – August 2015) involved monthly sampling at sites where screens were suspended at near-bottom locations for a 24h period and retrieved, with concurrent collections of macrophytes; including Halimeda, Laurencia, and Thalassia in the Florida Keys, and Dictyota in both regions. Gambierdiscus cells were identified and enumerated in the screen and macrophyte samples, and several regression techniques were evaluated (linear regression using untransformed and log-transformed data; negative binomial distribution (NBD) regression) to determine how well the screen-derived data could estimate algal cell concentrations on the host algae. In all cases, the NBD models performed the best based on Akaike Information Criteria values, although 38% of the regressions were not statistically-significant, including all of the St. Thomas sites. The r(2) values were all < 0.75 and averaged 0.36, indicating relatively poor fit of the screen data. False negative results (regression models underestimating actual cell abundances) were common occurrences, ranging from 5 to 74% of the scenarios tested. In summary, these results indicate that 24h screen deployments do not appear to be consistent in all situations. Caution is therefore needed when considering 24h screens as a standardized monitoring approach for quantifying Gambierdiscus population dynamics across geography and ecosystems. Furthermore, neutral (artificial) substrates may not adequately capture either the host preference or palatability that likely influence the initial vector of toxin incorporation in the food web via herbivory on these macrophytes.

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 &asymp, 250 fish by RBA indicated &asymp, 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.

Ciguatera fish poisoning (ciguatera) is a common clinical syndrome in areas where there is dependence on tropical reef fish for food. A subset of patients develops recurrent and, in some instances, chronic symptoms, which may result in substantial disability. To identify possible biomarkers for recurrent/chronic disease, and to explore correlations with immune gene expression, peripheral blood leukocyte gene expression in 10 ciguatera patients (7 recurrent and 3 acute) from the U.S. Virgin Islands, and 5 unexposed Florida controls were evaluated. Significant differences in gene expression were noted when comparing ciguatera patients and controls; however, it was not possible to differentiate between patients with acute and recurrent disease, possibly due to the small sample sizes involved.

The five most commonly recognized Harmful Algal Bloom-related illnesses are ciguatera poisoning, paralytic shellfish poisoning, neurotoxic shellfish poisoning (NSP), amnesic shellfish poisoning, and diarrhetic shellfish poisoning. Although these exposures result from exposure to different toxins or toxin congeners, these clinical syndromes have much in common. Exposure occurs through the consumption of fish, shellfish, or through exposure to aerosolized NSP toxins. Routine clinical tests are not available for the diagnosis of harmful algal bloom related illnesses, there is no known antidote for exposure, and the risk of these illnesses can negatively impact local fishing and tourism industries. The absence of exposure risk or diagnostic certainty can also precipitate a chain of events that results in considerable psychological distress for coastal populations. Thus, illness prevention is of paramount importance to minimize human and public health risks. To accomplish this, further transdisciplinary research, close communication and collaboration are needed among HAB scientists, public health researchers, and local, state and tribal health departments at academic, community outreach, and policy levels.