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An outbreak of food poisoning of unknown origin was notified to Central Queensland Public Health Unit on 9 December 2021. The bulk carrier sailing from Higashiharima, Japan to Gladstone, Australia reported an incident of sudden illness, with 19 out of 20 sailors on board reporting a combination of gastrointestinal and neurological symptoms. Central Queensland Public Health Unit started the outbreak investigation as per Queensland Health public health management guidelines. All 20 of the sailors consumed a self-caught barracuda and squid, prepared by the ship's cook, the day before. Unconsumed samples of the fish and squid were sent for testing. The affected sailors were triaged on arrival and were provided with medical care as required. The barracuda sample contained ciguatoxins (CTXs; P-CTX-1, P-CTX-2, P-CTX-3) with a total count of 3.40 ug/kg confirming the diagnosis. We propose the usage of the combination of gastrointestinal symptoms and paraesthesia in the light of a recent intoxication event for early detection of ciguatera poisoning (CP) in the eastern seaboard of Australia., (© Commonwealth of Australia CC BY-NC-ND)

Between 2014 and 2016, five cases of ciguatera fish poisoning (CFP), involving twenty four individuals, were linked to Spanish Mackerel (Scomberomorus commerson) caught in the coastal waters of the state of New South Wales (NSW) on the east coast of Australia. Previously, documented cases of CFP in NSW were few, and primarily linked to fish imported from other regions. Since 2015, thirteen individuals were affected across four additional CFP cases in NSW, linked to fish imported from tropical locations. The apparent increase in CFP in NSW from locally sourced catch, combined with the risk of CFP from imported fish, has highlighted several considerations that should be incorporated into risk management strategies to minimize CFP exposure for seafood consumers. [ABSTRACT FROM AUTHOR]

• Gambierdiscus honu is widespread throughout the Pacific with no significant genetic diversity patterns in commonly used rRNA operons. • Gambierdiscus honu is distributed within the expected sub-tropical to tropical range of Gambierdiscus species. • Isolates used in this study show Gambierdiscus honu is not a ciguatoxin producer. • Toxic compounds gambierone and 44-methylgambierone are produced by Gambierdiscus honu, and it is hypothesised additional secondary metabolites are produced. • Observed variation in toxicity levels of the ten Gambierdiscus honu isolates in this study do not relate to their phylogenetic grouping or location of origin. An increase in cases of ciguatera poisoning (CP) and expansion of the causative species in the South Pacific region highlight the need for baseline data on toxic microalgal species to help identify new areas of risk and manage known hot spots. Gambierdiscus honu is a toxin producing and potential CP causing dinoflagellate species, first described in 2017. Currently no high-resolution geographical distribution, intraspecific genetic variation or toxin production diversity data is available for G. honu. This research aimed to further characterize G. honu by investigating its distribution using species-specific real-time polymerase chain reaction assays at 25 sites in an area spanning ∼8000 km of the Coral Sea/Pacific Ocean, and assessing intraspecific genetic variation, toxicity and toxin production of isolated strains. Assessment of genetic variation of the partial rRNA operon of isolates demonstrated no significant intraspecific population structure, in addition to a lack of adherence to isolation by distance (IBD) model of evolution. The detected distribution of G. honu in the Pacific region was within the expected tropical to temperate latitudinal ranges of 10° to -30° and extended from Australia to French Polynesia. In the lipophilic fractions, the neuroblastoma cell-based assay (CBA-N2a) showed no ciguatoxin (CTX)-like activity for nine of the 10 isolates, and an atypical pattern for CAWD233 isolate which showed cytotoxic activity in OV- and OV+ conditions. In the same way, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis confirmed no Pacific-CTXs (CTX-3B, CTX-3C, CTX-4A, CTX-4B) were produced by the ten strains. The CBA-N2a assessment of the hydrophilic fractions showed moderate to high cytotoxicity in both OV- and OV+ condition for all the strains showing a cytotoxic profile similar to that of gambierone. Indeed, this study is the first to show the cytotoxic activity of gambierone on mouse neuroblastoma cells while no cytotoxicity was observed when 44-MG was analysed at the same concentrations using the CBA-N2a. Analysis of the hydrophilic via LC-MS/MS confirmed production of gambierone in all isolates, ranging from 2.1 to 38.1 pg/cell, with 44-methylgambierone (44-MG) also produced by eight of the isolates, ranging from 0.3 to 42.9 pg/cell. No maitotoxin-1 was detected in any of the isolates. Classification of the G. honu strains according to the quantities of gambierone produced aligned with the classification of their cytotoxicity using the CBA-N2a. Finally, no maitotoxin-1 (MTX) was detected in any of the isolates. This study shows G. honu is widely distributed within the Pacific region with no significant intraspecific population structure present. This aligns with the view of microalgal populations as global metapopulations, however more in-depth assessment with other genetic markers could detect further structure. Toxicity diversity across 10 isolates assessed did not display any geographical patterns. [Display omitted] [ABSTRACT FROM AUTHOR]

Increases in reported incidence of ciguatera fish poisoning (hereafter ciguatera) have been linked to warmer sea temperatures that are known to trigger coral bleaching events. The drivers that trigger blooms of ciguatera-causing dinoflagellates on the Great Barrier Reef (GBR) are poorly understood. This study investigated the effects of increased temperatures and lowered salinities, often associated with environmental disturbance events, on the population growth of two strains of the potentially ciguatera-causing dinoflagellate, Gambierdiscus carpenteri (NQAIF116 and NQAIF380). Both strains were isolated from the central GBR with NQAIF116 being an inshore strain and NQAIF380 an isolate from a stable environment of a large coral reef aquarium exhibit in ReefHQ, Townsville, Australia. Species of Gambierdiscus are often found as part of a mixed assemblage of benthic toxic dinoflagellates on macroalgal substrates. The effect of assemblage structure of dinoflagellates on the growth of Gambierdiscus populations has, however, not been explored. The study, therefore investigated the growth of G. carpenteri within mixed assemblages of benthic dinoflagellates. Population growth was monitored over a period of 28days under three salinities (16, 26 and 36) and three temperature (24, 28 and 34°C) conditions in a fully crossed experimental design. Temperature and salinity had a significant effect on population growth. Strain NQAIF380 exhibited significantly higher growth at 28°C compared to strain NQAIF116, which had highest growth at 24°C. When strain NQAIF116 was co-cultured with the benthic dinoflagellates, Prorocentrum lima and Ostreopsis sp., inhibitory effects on population growth were observed at a salinity of 36. In contrast, growth stimulation of G. carpenteri (strain NQAIF116) was observed at a salinity of 26 and particularly at 16 when co-cultured with Ostreopsis-dominated assemblages. Range expansion of ciguatera-causing dinoflagellates could lead to higher frequency of reported ciguatera illness in populated temperate Australian regions, outside the tropical range of the GBR. Therefore, the findings on salinity and temperature tolerance of two strains of G. carpenteri indicates potential adaptability to different local environmental conditions. These are baseline data for future investigations into the potential southward range expansion of ciguatera-causing dinoflagellates originating from the GBR., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Ciguatera fish poisoning is probably more important than any other form of seafood poisoning. Its epidemiology is complex and it is impossible to predict outbreaks. Toxic fish (which look, taste and smell normal) contain ciguatoxins derived from microalgae via the food chain. The toxins are not destroyed by cooking and, if consumed in sufficient dose, can cause symptoms persisting for weeks, months or years. The incidence of ciguatera is expected to increase in association with global warming and widespread bleaching and death of coral.

The consumption of seafood, which is contaminated by toxines of red tides, is a common cause of disease in tropic regions. The most important diseases, which are caused by red tides are Paralytic Shellfish Poisoning (PSP), Diarrhetic Shellfish Poisoning (DSP), Neurotoxic Shellfish Poisoning (NSP), Amnesic Shellfish Poisoning (ASP), Ciguatera Fish Poisoning (CFP).

We report a retrospective study of the clinical signs and symptoms associated with a point-source outbreak of fish poisoning that occurred with a fish captured from the Arafura Sea, northern Australia. Twenty cases (16 Aboriginal and 4 non-Aboriginal) characteristic of ciguatera, including 4 inpatients and 16 outpatients from the Gove Hospital, were identified based on the pattern of clinical symptoms and signs after ingestion of a large coral cod from a known ciguatera-prone coral reef. In the absence of a serologic test for the victim, laboratory analysis of a 230-g sample of the coral cod (Cephalopolis miniatus), using both mouse bioassay and HPLC/mass spectometry, showed that Pacific ciguatoxin-1 was the principal toxin involved. Intravenous mannitol was administered to one patient without clear benefit. Risk factors for ciguatera poisoning are ingestion of larger portions of reef fish from ciguatera-prone areas. Despite apparent local awareness of the distribution and etiology of the disease, large common-source outbreaks of ciguatera still occur.

Ciguatera is a toxin-related disease caused by ingestion of a variety of toxic fish living in tropical or subtropical areas. This article aims to look at the epidemiology of the disease, from both the descriptive and analytical points of view, and to discuss them in relation to environmental aspects and socioeconomic impact.

Fifteen cases of acute ciguatera poisoning were subjected to electrical studies on the sural and common peroneal nerves. Significant slowing of sensory conduction velocity and prolongation of the absolute refractory, relative refractory and supernormal periods were recorded. These findings indirectly suggest that ciguatoxin causes an abnormally prolonged sodium channel opening in nerve membranes.

Ciguatera is a type of food poisoning that results from eating certain tropical fish which have become toxic. It is common in Australia: 175 outbreaks, which involved 527 people, were reported in Queensland between 1965 and 1984. It seems restricted to certain areas around the Australian coastline. Most reports have involved the narrow-barred Spanish mackerel, Scomberomorus commersoni, most of which were caught in southern Queensland waters. Up to 2100 cases may have occurred in north Queensland between 1965 and 1984, which were not recorded by the writers. The symptoms of ciguatera in Australia are similar to those reported elsewhere in the South Pacific. Ciguatoxin acts by increasing the permeability of excitable membranes to sodium ions. This type of membrane is found throughout the body in nerve tissue as well as in heart and skeletal muscle. The treatment of ciguatera remains symptomatic and supportive only. Major advances in treatment for ciguatera and detection of ciguatoxin await the means of producing additional ciguatoxin.