A pilot study for the detection of acute ciguatera intoxication in human blood

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.

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).

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).

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.