Abstract
From September 1993 to October 1994, a total of 75 catfish, Silurus asotus, was caught in Aomori Prefecture and was examined for gnathostome larvae. Approximately half (35) of the catfish were infected, all of which were 30 cm or longer in body length. The infected catfish harbored from 1 to 13 larvae, and a total of 90 larvae was recovered. According as the body length of the catfish increased, the infection rate and intensity of infection also increased. Taxonomically, all the larvae were identified as the advanced third-stage larvae of Gnathostoma nipponicum. Regarding as the location of the larvae, most (88.9%) were recovered from the viscera, such as mesenterium, gastro-intestinal walls, and serosa. Under undigested examination, more than half of the larvae in visceral tissues showed partial degeneration or death.
From these findings, it suggests that although catfish are susceptible to this parasite, they may not be very suitable hosts as the second intermediate and/or paratenic hosts of G. nipponicum.
Key words: Gnathostoma nipponicum; advanced third-stage larva; catfish; Silurus asotus; survey.