Abstract
Between 1994 and 1998, epizootiological investigations were conducted on kudoosis amami caused by Kudoa amamiensis (Multivalvulida : Myxozoa) in yellowtail Seriola quinqueradiata and amberjack Seriola dumerili at 14 coastal areas in Okinawa Prefecture, Japan. Surveys indicated that the geographical distribution of K. amamiensis was limited specifically within a local area; the prevalences of infection were 70-100% in yellowtail and 30-90% in amberjack in the Motobu area, whereas they were 0-9% in yellowtail and 0-1% in amberjack in the other areas examined. Amberjack were less susceptible to K. amamiensis than yellowtail; the intensities of infection (number of pseudocysts per one gram of muscle tissue) in amberjack were one order of magnitude lower than those in yellowtail. Infections with K. iwatai forming similar pseudocysts in the musculature were rarely found, and the intensities of infection were remarkably lower than those of K. amamiensis.
