RESUMO
Ciguatera in humans is typically caused by the consumption of reef fish that have accumulated Ciguatoxins (CTXs) in their flesh. Over a six month period, we captured 38 wild adult great barracuda (Sphyraena barracuda), a species commonly associated with ciguatera in The Bahamas. We sampled three tissues (i.e., muscle, liver, and blood) and analysed them for the presence of ciguatoxins using a functional in vitro N2A bioassay. Detectable concentrations of ciguatoxins found in the three tissue types ranged from 2.51 to 211.74pg C-CTX-1 equivalents/g. Blood and liver toxin concentrations were positively correlated (ρ=0.86, P=0.003), indicating that, for the first time, blood sampling provides a non-lethal method of detecting ciguatoxin in wild fish. Non-lethal blood sampling also presents opportunities to couple this approach with biotelemetry and biologging techniques that enable the study of fish distribution and movement. To demonstrate the potential for linking ciguatoxin occurrence with barracuda spatial ecology, we also present a proof-of-concept case study where blood samples were obtained from 20 fish before releasing them with acoustic transmitters and tracking them in the coastal waters using a fixed acoustic telemetry array covering 44km(2). Fish that tested positive for CTX may have smaller home ranges than non-toxic fish (median distance travelled, U=2.21, P=0.03). Results presented from this study may help identify high risk areas and source-sink dynamics of toxins, potentially reducing the incidence and human health risk of ciguatera fish poisoning. Moreover, development of the non-lethal sampling approach and measurement of ciguatera from blood provide future opportunities to understand the mechanistic relationship between toxins and the spatial ecology of a broad range of marine fish species.
Assuntos
Comportamento Animal , Coleta de Amostras Sanguíneas/métodos , Ciguatoxinas/sangue , Monitoramento Ambiental/métodos , Peixes/fisiologia , Telemetria/métodos , Acústica , Animais , Bahamas , Fígado/química , Músculos/química , Estações do Ano , Estatísticas não ParamétricasRESUMO
INTRODUCTION: Ciguatera fish poisoning arises from consumption of any of the 400 species of tropical marine reef fish containing polyether toxins. No laboratory method is available for clinical diagnosis of acute ciguatera poisoning. The objective of this pilot study was to ascertain the potential usefulness of a bioassay to detect ciguatoxins in humans suspected of acute intoxication. We analyzed plasma of healthy volunteers (asymptomatic negative controls), participants with gastrointestinal (GI) illness but without recent fish consumption (symptomatic negative controls), and participants with GI illness who had recently consumedfish. MATERIALS AND METHODS: Blood samples, questionnaires, and consent forms were collected from 11 symptomatic negative controls and 86 patients that visited emergency rooms in southern Puerto Rico over a 1-year period. Patients had consumed fish within 24 hour prior to the symptoms. Plasma samples were analyzed by a neuroblastoma cell bioassay that detects seafood toxins active at the sodium voltage-gated channel in a dose-dependent fashion. Concentrations were expressed in terms of brevetoxin-1 equivalents (ng PbTx-1 equiv/mL). RESULTS: The mean plasma concentration of 14 asymptomatic negative controls was 39.4 ng PbTx-1 equiv/mL (range 2-74). Of 86 potential ciguatoxic patients who reported fish consumption, 43 had values within the range of normal volunteers, and 9 had concentrations in the nondiagnostic range (73.9-100 ng). Thirty-four patients (40%) had concentrations 3 standard deviations above asymptomatic negative controls (>100 ng PbTx-1 equiv/mL). They had a mean concentration of 1,074 +/- 244.5 ng PbTx-1 equiv/mL (range 101-7,056ng). CONCLUSION: Preliminary findings of elevated PbTx-1 equivalents in 40% of the patients with both ciguatera symptomatology and fish consumption in a geographical area where ciguatera is common suggest that the neuroblastoma bioassay may be a potential diagnostic tool for acute ciguatera intoxication.