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.

Family tetrodotoxin poisoning in Reunion Island (Southwest Indian Ocean) following the consumption of Lagocephalus sceleratus (Pufferfish).

Pufferfish poisoning has rarely been reported in the southwestern Indian Ocean and in the French overseas territories. In Reunion Island, the last notified documented case occurred in 1989 and people are no longer aware of the potential toxicity of pufferfish. We report a family hospitalized for a tetrodotoxin poisoning following the consumption of Lagocephalus sceleratus caught on the coast of Reunion Island in September 2013. Two patients presenting acute vital functions failures were admitted in an ICU. Ten people were admitted simultaneously to the emergency department after consuming L. sceleratus with signs of toxicity appearing within 2 hours. Treatment was supportive, but included the need for mechanical ventilation for two patients. All those affected had complete and uneventful recoveries within a few days. The fish consumed was identified as L. sceleratus, a species known to contain tetrodotoxin. The diagnosis of tetrodotoxin poisoning was suggested by typical clinical manifestations together with the history of very recent consumption of tetrodotoxin-containing fish. Tetrodotoxin was later detected at high levels in food remnants. To the best of our knowledge, there has been no documented case series of tetrodotoxin poisoning reported from Reunion Island for the last 25 years and from the entire Indian Ocean area since 1998. Pufferfish intoxication is one of the most common causes of poisoning among people in coastal regions of Asia but it has also recently been reported in areas where it was previously unknown, particularly along the Mediterranean shores and in Spain. Public health education in French overseas territories and along the Mediterranean shores should be adapted to include increased awareness of the danger of consuming pufferfish. Health teams must be aware of such clinical presentations.

Marine fish communities in shallow volcanic habitats.

This survey of the marine ichthyofauna of the Piton de La Fournaise volcano at Reunion Island is the first explanatory study of fish community structures in this area. It describes and analyses the main qualitative descriptors of the fish communities (i.e. species richness, diet, life history and geographical distribution) and their spatio-temporal organization. This investigation in 2011 examined lava flows of different ages, including the most recent flows that entered the ocean between 1977 and 2007. In all, 263 species belonging to 45 families were observed. Overall, the fish community was notable for an absence of top predators and a predominance of opportunistic small-bodied species, with dietary flexibility and high reproductive rates, characteristic of the early stages of ecological succession. Between-site analysis indicated that the fish assemblages differed essentially according to the intensity of the last volcanic disturbances. Fish communities in the most disturbed sites showed the highest numbers of Serranidae and the highest proportions of omnivores and small-bodied opportunistic carnivores, including a high proportion of endemic south-western Indian Ocean species. The spatial pattern of this last category of species could be the result of convergent biological traits, and their adaptation to unstable environments at the expense of their competitiveness in more biodiverse, mature communities. Conversely, fish communities in the less disturbed sites showed the highest number of Holocentridae and the highest proportion of browsers of sessile invertebrates. This last characteristic could be a consequence of higher ecological maturity, illustrated by a more specialized trophic network, for assemblages in areas with less intense disturbances. Otherwise, high structural complexity, either in unconsolidated lava boulders, rocks and rubble or high coral-covered sites, could favour the increase of the total number of species independent of disturbance intensity. Regarding the broader effects, this study helps better understand how ecosystems can resist or recover from acute disturbances and the process of ecological succession that leads to the establishment of fish communities in newly submerged habitats.

Morphological and toxicological variability of Prorocentrum lima clones isolated from four locations in the south-west Indian Ocean.

Eight clones of the toxic dinoflagellate Prorocentrum lima (Ehrenberg) Dodge from four sites (two clones per site) on the coral reef of La Réunion, Mayotte, Europa, and Mauritius Islands in the SW Indian Ocean were isolated and cultivated under the same conditions. Morphological features of each clone, including cell size and valve and marginal pore numbers, were examined by scanning electron microscopy. The toxic potential of each clone was determined by protein phosphatase type 2A (PP2A) inhibition test and fibroblast cell line FR3T3 bioassay. Scanning electron microscopy showed that variation in morphological features of clones within and between sites was minimal and not significant. However, equivalent okadaic acid content, determined by PP2A assay, was different within and between clones isolated from the four islands. Cytotoxicity bioassay with the FR3T3 cell line confirmed the variation on global toxic potential within and between the eight P. lima clones. This test also suggested the presence of other toxic compounds without PP2A inhibiting activity in crude extracts of some clones.

Ciguatera in Réunion Island (SW Indian Ocean): epidemiology and clinical patterns.

One hundred and fifty-nine ichtyosarcotoxic outbreaks, including 477 people, were recorded in the island of Réunion (SW Indian ocean) between 1986 and 1994. Ciguatera outbreaks represented 78.6% of the total cases and its annual incidence rate was estimated to be 0.78/10,000 residents. Symptoms caused by ciguatera poisoning are not different from those reported in Pacific and Caribbean islands, except for the additional symptoms of hallucinatory poisoning in 16% of the patients. Serranidae fish, including species of great commercial value, were the most commonly incriminated accounting for 50% of the outbreaks.

Selection of cytotoxic responses to maitotoxin and okadaic acid and evaluation of toxicity of dinoflagellate extracts.

The cytotoxicity of maitotoxin (MTX) and okadaic acid (OA) was studied on three mammalian fibroblast cell lines. Neutral red uptake (NRU), which measures cell viability, and morphological alterations were selected as rapid suitable responses. NRU allowed a precise toxicity quantification while the observations of morphological damage revealed differences specific to MTX (cell blebbing) and OA (cell rounding). BHK21 C13 fibroblasts, although less sensitive to MTX than the other cell lines, were chosen since they gave stable information and a two-stage morphological response with OA ("square"-shaped cells, then round cells). When NRU and morphology alterations were studied with crude extracts of Gambierdiscus toxicus and Prorocentrum lima, responses were typical of the dominant toxins, MTX and OA or related toxins respectively. Applied to several dinoflagellate extracts, the two tests revealed no toxicity for Amphidinium carterae, Ostreopsis siamensis, O. ovata and Coolia monotis (from La Réunion) and toxicity for A. carterae and A. operculatum (from Saint Barthélémy). When toxic, A. carterae extracts showed blebbing similar to that caused by MTX. Morphology alterations caused by A. operculatum crude extracts, different from those corresponding to MTX or OA, were also observed.

Evolution of Gambierdiscus toxicus populations in the coral reef complex of Mayotte Island (SW Indian Ocean) during the 1985-1991 period.

Evolution of the Gambierdiscus toxicus populations during the 1979/1985-1991 period shows an increase of the average densities until 1988-Sept. that seems linked with climatic parameters (insolation, rainfalls) but mainly with anthropogenetic disturbances. After a bloom the populations are now stabilized at a level higher than at the beginning of the monitoring. Without clear correlation, Gtx densities seems associated to physical and chemical features of the lagoonal and reefal waters.