THE USE OF THE MOSQUITO BIOASSAY FOR DETERMINING THE TOXICITY TO MAN OF CIGUATERIC FISH

¹ Institut Territorial de Recherches Medicales, "Louis Malarde," B. P. 30, Papeete, Tahiti, French Polynesia

Moderately well-correlated with the mouse bioassay, requiring a much smaller amount of raw fish flesh, and employing a faster chemical extraction procedure, the mosquito bioassay represents significant progress in detecting ciguatoxin in fish muscle. We use the mosquito bioassay to evaluate the approximate amount of ciguatoxin present in the remains of 25 fish of 17 different species involved in 99 documented cases of ciguatera poisoning. From the data provided by mosquito bioassay and human symptomatology, we determine a dose-effect relationship for ciguatoxin (CTX) to man. Three average pathogenic doses (PD) are established. The minimum PD is estimated to be 0.6 ng CTX/kg, the PD5O to be 2 ng CTX/kg, and the PD100 to be 8 ng CTX/kg. These data suggest a MLD (minimal lethal dose) value of 20 ng CTX/kg.