Prevalence and proposal for cost-effective management of the ciguatera risk in the Noumea fish market, New Caledonia (South Pacific)

The Prevalence of Marine Lipophilic Phycotoxins Causes Potential Risks in a Tropical Small Island Developing State

Tropical small island developing states (SIDS), with their geographical isolation and limited resources, heavily rely on the fisheries industry for food and revenue. The presence of marine lipophilic phycotoxins (MLPs) poses risks to their economy and human health. To understand the contamination status and potential risks, the Republic of Kiribati was selected as the representative tropical SIDS and 55 species of 256 coral reef fish encompassing multiple trophic levels and feeding strategies were collected to analyze 17 typical MLPs. Our results showed that the potential risks of ciguatoxins were the highest and approximately 62% of fish species may pose risks for consumers. Biomagnification of ciguatoxins was observed in the food web with a trophic magnification factor of 2.90. Brevetoxin-3, okadaic acid, and dinophysistoxin-1 and -2 were first reported, but the risks posed by okadaic acid and dinophysistoxins were found to be negligible. The correlation analysis revealed that fish body size and trophic position are unreliable metrics to indicate the associated risks and prevent the consumption of contaminated fish. The potential risks of MLPs in Kiribati are of concern, and our findings can serve as valuable inputs for developing food safety policies and fisheries management strategies specific to tropical SIDS contexts.

Local and Traditional Ecological Knowledge of Fish Poisoning in Fiji

Fish poisoning (FP) affects human health, trade and livelihood in Fiji, where management has depended mainly on traditional ecological knowledge (TEK). This paper investigated and documented this TEK through a 2-day stakeholder workshop, group consultation, in-depth interviews, field observations, and analyses of survey data from the Ministry of Fisheries, Fiji. Six TEK topics were identified and classified as preventative and treatment options. The preventive approach involves identifying toxic reef fishes, the spawning season of edible seaworms, hotspot areas of toxic fishes, folk tests, and locating and removing toxic organs. For example, 34 reef fish species were identified as toxic. The FP season was associated with the spawning of balolo (edible seaworm) and the warmer months of October to April (cyclone seasons). Two well-known toxic hotspots associated with an abundance of bulewa (soft coral) were identified. Folk tests and locating and removing toxic fish organs are also practised for moray eels and pufferfish. At the same time, various locally available herbal plants are used to treat FP as the second line of defence. The TEK collated in this work can help local authorities better identify the sources of toxicity, and applying TEK preventive measures could stem the tide of fish poisoning in Fiji.

Evaluating Age and Growth Relationship to Ciguatoxicity in Five Coral Reef Fish Species from French Polynesia

Ciguatera poisoning (CP) results from the consumption of coral reef fish or marine invertebrates contaminated with potent marine polyether compounds, namely ciguatoxins. In French Polynesia, 220 fish specimens belonging to parrotfish (Chlorurus microrhinos, Scarus forsteni, and Scarus ghobban), surgeonfish (Naso lituratus), and groupers (Epinephelus polyphekadion) were collected from two sites with contrasted risk of CP, i.e., Kaukura Atoll versus Mangareva Island. Fish age and growth were assessed from otoliths’ yearly increments and their ciguatoxic status (negative, suspect, or positive) was evaluated by neuroblastoma cell-based assay. Using permutational multivariate analyses of variance, no significant differences in size and weight were found between negative and suspect specimens while positive specimens showed significantly greater size and weight particularly for E. polyphekadion and S. ghobban. However, eating small or low-weight specimens remains risky due to the high variability in size and weight of positive fish. Overall, no relationship could be evidenced between fish ciguatoxicity and age and growth characteristics. In conclusion, size, weight, age, and growth are not reliable determinants of fish ciguatoxicity which appears to be rather species and/or site-specific, although larger fish pose an increased risk of poisoning. Such findings have important implications in current CP risk management programs.

Digital Technologies and Open Data Sources in Marine Biotoxins' Risk Analysis: The Case of Ciguatera Fish Poisoning

Currently, digital technologies influence information dissemination in all business sectors, with great emphasis put on exploitation strategies. Public administrations often use information systems and establish open data repositories, primarily supporting their operation but also serving as data providers, facilitating decision-making. As such, risk analysis in the public health sector, including food safety authorities, often relies on digital technologies and open data sources. Global food safety challenges include marine biotoxins (MBs), being contaminants whose mitigation largely depends on risk analysis. Ciguatera Fish Poisoning (CFP), in particular, is a MB-related seafood intoxication attributed to the consumption of fish species that are prone to accumulate ciguatoxins. Historically, CFP occurred endemically in tropical/subtropical areas, but has gradually emerged in temperate regions, including European waters, necessitating official policy adoption to manage the potential risks. Researchers and policy-makers highlight scientific data inadequacy, under-reporting of outbreaks and information source fragmentation as major obstacles in developing CFP mitigation strategies. Although digital technologies and open data sources provide exploitable scientific information for MB risk analysis, their utilization in counteracting CFP-related hazards has not been addressed to date. This work thus attempts to answer the question, "What is the current extent of digital technologies' and open data sources' utilization within risk analysis tasks in the MBs field, particularly on CFP?", by conducting a systematic literature review of the available scientific and grey literature. Results indicate that the use of digital technologies and open data sources in CFP is not negligible. However, certain gaps are identified regarding discrepancies in terminology, source fragmentation and a redundancy and downplay of social media utilization, in turn constituting a future research agenda for this under-researched topic.

Ciguatera poisonings: A global review of occurrences and trends

Ciguatera Poisoning (CP) is the most prevalent, phycotoxin related seafood poisoning across the globe, affecting between 10,000 and 50,000 people annually. This illness results from the consumption of seafood contaminated with lipid soluble toxins known as ciguatoxins (CTXs) that are produced by benthic dinoflagellates in the genera Gambierdiscus and Fukuyoa. The present work reviews the global occurrence of CP events and outbreaks, based on both scientific and gray literature. Ciguatera prevalence is significantly underestimated due to a lack of recognition of ciguatera symptoms, limited collection of epidemiological data on a global level, and reticence to report ciguatera in CP-endemic regions. Analysis of the time-series data available for a limited number of countries indicates the highest incidence rates are consistently reported from two historical CP-endemic areas i.e., the Pacific and Caribbean regions, a situation due in part to the strong reliance of local communities on marine resources. Ciguatera-related fatalities are rare (<0.1% of reported cases). The vast majority of outbreaks involve carnivorous fish including snappers, groupers, wrasses, and barracudas. Since 2000, an expansion of the geographical range of CP has been observed in several areas like Macaronesia and east and southeast Asia. In some of these locales, random surveys confirmed the presence of CTXs in locally sourced fish, consistent with the concurrent report of novel CP incidents (e.g., Canary Islands, Madeira, Selvagens Islands, New South Wales). One characteristic of outbreaks occurring in Asia is that they often present as large disease clusters due to group consumption of a single contaminated fish. Similar observations are reported from the Indian Ocean in the form of shark poisoning outbreaks which often lead to singular types of CP characterized by a high fatality rate. Other atypical forms of CP linked to the consumption of marine invertebrates also have been documented recently. Owing to the significant health, socioeconomic and socio-cultural impacts of ciguatera, there is an urgent need for increased, standardized, coordinated efforts in ciguatera education, monitoring and research programs. Several regional and international initiatives have emerged recently, that may help improve patients' care, data collection at a global scale, and risk monitoring and management capabilities in countries most vulnerable to CP's toxic threat.

Presence of CTXs in moray eels and dusky groupers in the marine environment of the Canary Islands

Local population frequently consumes moray eels and dusky groupers from the Canary Islands. These species are top predators and the interactions between them include predation but also, in some cases, collaborative hunting. These fish are well known to cause ciguatera (CFP) outbreaks in several marine areas such as Japan, Hawaii, French Polynesia and Caribe. Groupers have been involved in CFP events in the Canary Islands, however, moray eels have not yet been well studied in this regard. The present research seeks to describe the finding of a black moray in the stomach of a positive dusky grouper during its necropsy, and to clarify the implication of groupers and moray eels in the food webs, accumulating CTXs in the Canarian environment. The study also updates statistics on the presence of toxic groupers in this archipelago. For these purposes, 248 grouper samples from the CFP official control in the Canary Islands (2018-2019) were analysed and 36 moray eels (5 species) were collected under the EuroCigua project and one was obtained during a dusky grouper necropsy. All samples were analysed with the Neuro-2a cell-based assay (CBA) to evidence CTX-like toxicity. Regarding the necropsied grouper and the moray eel found in its stomach content, the LCMS/MS method allowed the identification and quantification of CCTX1 in both fish at similar levels while none of the P-CTXs for which standards were available were detected. Among groupers, 25.4 % displayed CTX-like toxicity with differences between islands. For moray eels 38.9 % showed toxicity, involving 4 species. Black moray exhibited a high proportion of positives (9/12) and a positive correlation was found between CTX-like toxicity quantification and the black moray weight. Regarding the grouper, and the moray eel found in its stomach, the LCMS/MS method allowed the identification and quantification of C-CTX1 in both fish at similar levels. This found suggests a trophic interaction between these species and their role in maintaining CTXs in the Canary waters where local population commonly demand those species for consumption. The island of El Hierro stands out above all the other Canary Islands with the concerning percentage of positive grouper samples and the high CTX toxicity levels obtained in moray eel specimens analysed in this marine area. This is the first report of CTX-like toxicity in flesh of moray eels fished in the Canary archipelago and the confirmation of the presence of C-CTX1 by LCMS/MS in a black moray from this marine area.

Experimental evidence of dietary ciguatoxin accumulation in an herbivorous coral reef fish

Ciguatoxins (CTXs) are potent algal toxins that cause widespread ciguatera poisoning and are found ubiquitously in coral reef food webs. Here we developed an environmentally-relevant, experimental model of CTX trophic transfer involving dietary exposure of herbivorous fish to the CTX-producing microalgae Gambierdiscus polynesiensis. Juvenile Naso brevirostris were fed a gel-food embedded with microalgae for 16 weeks (89 cells g^-1 fish daily, 0.4 μg CTX3C equiv kg^-1 fish). CTXs in muscle tissue were detectable after 2 weeks at levels above the threshold for human intoxication (1.2 ± 0.2 μg CTX3C equiv kg^-1). Although tissue CTX concentrations stabilized after 8 weeks (∼3 ± 0.5 μg CTX3C equiv kg^-1), muscle toxin burden (total μg CTX in muscle tissue) continued to increase linearly through the end of the experiment (16 weeks). Toxin accumulation was therefore continuous, yet masked by somatic growth dilution. The observed CTX concentrations, accumulation rates, and general absence of behavioural signs of intoxication are consistent with field observations and indicate that this method of dietary exposure may be used to develop predictive models of tissue-specific CTX uptake, metabolism and depuration. Results also imply that slow-growing fish may accumulate higher CTX flesh concentrations than fast-growing fish, which has important implications for global seafood safety.

Regional Variations in the Risk and Severity of Ciguatera Caused by Eating Moray Eels

Moray eels (Gymnothorax species) from tropical waters have long been known to be high-risk species, and the consumption of particularly the viscera or ungutted eels can result in severe ciguatera (known as Gymnothorax or moray eel poisoning), characterized by prominent neurological features. In this review, the main objective was to describe the risk and severity of ciguatera caused by eating moray eels in different parts of the world. Moray eels can accumulate very high ciguatoxin (CTX) levels in the flesh and particularly the liver. Therefore, even the smaller ones can be toxic and the consumption of an average portion (particularly liver) can result in severe or fatal ciguatera. Moray eels (particularly when ungutted) must never be served in gatherings since they can cause mass poisoning because of their large sizes and high CTX levels. Apart from regulatory measures restricting or excluding access, the public should be repeatedly warned to avoid eating moray eels.

An Updated Review of Ciguatera Fish Poisoning: Clinical, Epidemiological, Environmental, and Public Health Management

Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world. It causes substantial human health, social, and economic impacts. The illness produces a complex array of gastrointestinal, neurological and neuropsychological, and cardiovascular symptoms, which may last days, weeks, or months. This paper is a general review of CFP including the human health effects of exposure to ciguatoxins (CTXs), diagnosis, human pathophysiology of CFP, treatment, detection of CTXs in fish, epidemiology of the illness, global dimensions, prevention, future directions, and recommendations for clinicians and patients. It updates and expands upon the previous review of CFP published by Friedman et al. (2008) and addresses new insights and relevant emerging global themes such as climate and environmental change, international market issues, and socioeconomic impacts of CFP. It also provides a proposed universal case definition for CFP designed to account for the variability in symptom presentation across different geographic regions. Information that is important but unchanged since the previous review has been reiterated. This article is intended for a broad audience, including resource and fishery managers, commercial and recreational fishers, public health officials, medical professionals, and other interested parties.

Ciguatoxic Potential of Brown-Marbled Grouper in Relation to Fish Size and Geographical Origin

To determine the ciguatoxic potential of brown-marbled grouper (Epinephelus fuscoguttatus) in relation to fish size and geographical origin, this review systematically analyzed: 1) reports of large ciguatera outbreaks and outbreaks with description of the fish size; 2) Pacific ciguatoxin (P-CTX) profiles and levels and mouse bioassay results in fish samples from ciguatera incidents; 3) P-CTX profiles and levels and risk of toxicity in relation to fish size and origin; 4) regulatory measures restricting fish trade and fish size preference of the consumers. P-CTX levels in flesh and size dependency of toxicity indicate that the risk of ciguatera after eating E. fuscoguttatus varies with its geographical origin. For a large-sized grouper, it is necessary to establish legal size limits and control measures to protect public health and prevent overfishing. More risk assessment studies are required for E. fuscoguttatus to determine the size threshold above which the risk of ciguatera significantly increases.

Ciguatera fish poisoning in East Asia and southeast Asia

In the coastal countries of East Asia and Southeast Asia, ciguatera should be common because of the extensive tropical and subtropical coral reefs along the coasts and in the neighboring seas with ciguatoxic fishes. An extensive search of journal databases, the Internet and the government websites was performed to identify all reports of ciguatera from the regions. Based on the official data and large published case series, the incidence of ciguatera was higher in the coastal cities (Hong Kong, Foshan, Zhongshan) of southern China than in Japan (Okinawa Prefecture). In Singapore, ciguatera appeared to be almost unknown. In other countries, only isolated cases or small case series were reported, but under-reporting was assumed to be common. Ciguatera may cause severe acute illness and prolonged neurological symptoms. Ciguatera represents an important public health issue for endemic regions, with significant socio-economic impact. Coordinated strategies to improve risk assessment, risk management and risk communication are required. The systematic collection of accurate data on the incidence and epidemiology of ciguatera should enable better assessment and management of its risk. Much more work needs to be done to define the size threshold for important coral reef fish species from different regions, above which the risk of ciguatera significantly increases.

A phylogenetic re-analysis of groupers with applications for ciguatera fish poisoning

BACKGROUND

Ciguatera fish poisoning (CFP) is a significant public health problem due to dinoflagellates. It is responsible for one of the highest reported incidence of seafood-borne illness and Groupers are commonly reported as a source of CFP due to their position in the food chain. With the role of recent climate change on harmful algal blooms, CFP cases might become more frequent and more geographically widespread. Since there is no appropriate treatment for CFP, the most efficient solution is to regulate fish consumption. Such a strategy can only work if the fish sold are correctly identified, and it has been repeatedly shown that misidentifications and species substitutions occur in fish markets.

METHODS

We provide here both a DNA-barcoding reference for groupers, and a new phylogenetic reconstruction based on five genes and a comprehensive taxonomical sampling. We analyse the correlation between geographic range of species and their susceptibility to ciguatera accumulation, and the co-occurrence of ciguatoxins in closely related species, using both character mapping and statistical methods.

RESULTS

Misidentifications were encountered in public databases, precluding accurate species identifications. Epinephelinae now includes only twelve genera (vs. 15 previously). Comparisons with the ciguatera incidences show that in some genera most species are ciguateric, but statistical tests display only a moderate correlation with the phylogeny. Atlantic species were rarely contaminated, with ciguatera occurrences being restricted to the South Pacific.

CONCLUSIONS

The recent changes in classification based on the reanalyses of the relationships within Epinephelidae have an impact on the interpretation of the ciguatera distribution in the genera. In this context and to improve the monitoring of fish trade and safety, we need to obtain extensive data on contamination at the species level. Accurate species identifications through DNA barcoding are thus an essential tool in controlling CFP since meal remnants in CFP cases can be easily identified with molecular tools.

Large outbreaks of ciguatera after consumption of brown marbled grouper

Brown marbled grouper (Epinephelus fuscoguttatus) is an apex predator from coral reefs of the Indo-Pacific region. All five published case series of ciguatera after consumption of brown marbled grouper were reviewed to characterize the types, severity and chronicity of ciguatera symptoms associated with its consumption. Three of these case series were from large outbreaks affecting over 100–200 subjects who had eaten this reef fish served at banquets. Affected subjects generally developed a combination of gastrointestinal, neurological and, less commonly, cardiovascular symptoms. Gastrointestinal symptoms occurred early and generally subsided in 1–2 days. Some neurological symptoms (e.g., paresthesia of four limbs) could last for weeks or months. Sinus bradycardia and hypotension occurred early, but could be severe and prolonged, necessitating the timely use of intravenous fluids, atropine and dopamine. Other cardiovascular and neurological features included atrial ectopics, ventricular ectopics, dyspnea, chest tightness, PR interval >0.2 s, ST segment changes, polymyositis and coma. Concomitant alcohol consumption was associated with a much higher risk of developing bradycardia, hypotension and altered skin sensation. The public should realize that consumption of the high-risk fish (especially the ciguatoxin-rich parts and together with alcohol use) and repeated ciguatoxin exposures will result in more severe and chronic illness.

Ciguatera fish toxicity in French Polynesia: size does not always matter

Accumulation of ciguatoxins (CTXs) in tropical reef fish tissues during their life is responsible of the most prevalent human seafood intoxication in the South Pacific called Ciguatera Fish Poisoning (CFP). It has been assumed for a long time that CTXs are transferred and accumulated along the trophic food chain, and consequently that smaller individuals within a given fish species are safer to eat than larger ones. However, the relationship between toxicity and fish size has been studied for a limited number of species only and the conclusions are often contradictory. The toxicity of 856 fishes from 59 different species sampled in six islands in French Polynesia between 2003 and 2011 was assessed by Receptor Binding Assay. Among them, 45 species × island and 32 families × island for which the number of individuals was ≥6 allowed testing the relationship between toxicity and size. Except for six specimens of Lutjanus bohar caught in Fakarava (P < 0.01; R(2) = 0.854), the 44 remaining species × island showed no significant increase of CTXs concentration with fish total length (TL). Moreover, the proportion of toxic individuals decreased significantly for Epinephelus polyphekadion from Fakarava (n = 24; P < 0.05) and Kyphosus cinerascens from Raivavae (n = 29; P < 0.05), while no significant variation was detected for the other 43 species × island. At the family level, only three positive and three negative relationships between size and CTXs concentration were observed among the 32 family × island analyzed. No relationship between the proportion of toxic fish within a family and the relative total length of individuals were observed. The lack of relationship between toxicity and size observed for most of the species and families from the six islands suggests that fish size cannot be used as an efficient predictor of fish toxicity in French Polynesia. These results highlight the need for improving our knowledge about metabolic processes which may play a role in CTXs bio-accumulation and depuration among the different trophic levels of fishes.

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

The ouabain/veratridine-dependent neuroblastoma (neuro-2a) cell-based assay (CBA) was applied for the determination of the presence of ciguatoxin (CTX)-like compounds in ciguatera-suspected fish samples caught in the Canary Islands. In order to avoid matrix interferences the maximal concentration of wet weight fish tissue exposed to the neuro-2a cells was set at 20 mg tissue equivalent (TE) ml(-1) according to the sample preparation procedure applied. In the present study, the limit of quantification (LOQ) of CTX1B equivalents in fish extract was set at the limit of detection (LOD), being defined as the concentration of CTX1B equivalents inhibiting 20% cell viability (IC(20)). The LOQ was estimated as 0.0096 ng CTX1B eq.g TE(-1) with 23-31% variability between experiments. These values were deemed sufficient even though quantification given at the IC(50) (the concentration of CTX1B equivalents inhibiting 50% cell viability) is more accurate with a variability of 17-19% between experiments. Among the 13 fish samples tested, four fish samples were toxic to the neuro-2a cells with estimations of the content in CTX1B g(-1) of TE ranging from 0.058 (± 0.012) to 6.23 (± 0.713) ng CTX1B eq.g TE(-1). The high sensitivity and specificity of the assay for CTX1B confirmed its suitability as a screening tool of CTX-like compounds in fish extracts at levels that may cause ciguatera fish poisoning. Species identification of fish samples by DNA sequence analysis was conducted in order to confirm tentatively the identity of ciguatera risk species and it revealed some evidence of inadvertent misidentification. Results presented in this study are a contribution to the standardisation of the neuro-2a CBA and to the risk analysis for ciguatera in the Canary Islands.