Detection of Ciguatera and Diarrheic Shellfish Toxins in Finfish and Shellfish With Ciguatect Kit

Abstract

The Ciguatect test kit for the detection of ciguatoxin, okadaic acid, and related polyether compounds, based on solid-phase immunobead assay technology, was developed for rapid screening of toxic fish and shellfish in harvesting areas and the marketplace. Earlier formats, based on radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) technology, were used successfully to identify and separate ciguatoxic fish harvested from Hawaiian waters. The new format utilizes a membrane attached to a plastic strip, immunobead solution, and a user-friendly readout. Multiple formats of the test kit, including a rapid extraction method (REM) and ELISA, were demonstrated to be more sensitive than the mouse assay for detection of ciguatera-related compounds. Depending on the format used, the level of detection can be as low as 50 pg okadaic acid per gram of tissue. The test kit has been used to map ciguatoxic and nontoxic fishing areas around the islands of Hawaii through the use of a biomarker and the monitoring of toxic fish obtained from Pacific and Caribbean regions. Ciguatera-related toxins can be detected directly on fish flesh or after extraction by traditional procedures or the newly developed REM. Initial applications of the test kit to monitor diarrheic shellfish poisoning (DSP)-related toxins in mussels before, during, and after Dinophysis sp. blooms and during depuration operations were successful. The Ciguatect methodology can be used to monitor reef fishing areas for ciguatera potential, shellfish beds for DSP toxins, and shellfish depuration operations for elimination of DSP toxins and to screen for toxic fish and shellfish in the marketplace.