Effectiveness of ultraviolet irradiation of seawater for the prevention of kudoa yasunagai and kudoa amamiensis (Myxozoa: Multivalvulida) infections in Seriola fish

Abstract

Kudoa infections have recently become a serious concern in Japanese fisheries. Some species not only cause fish diseases and reduce the commodity value of fish, but also affect human health. We investigated whether the ultraviolet (UV) treatment of culture water prevented infections with two species of Kudoa, K. yasunagai and K. amamiensis, in Seriola lalandi and S. quinqueradiata, respectively. Rearing in untreated filtered seawater resulted in high infection rates, suggesting that the physical filtration systems used in this study did not sufficiently remove the infective stages of these Kudoa species. In contrast, commercially available UV irradiation system effectively prevented the infections with K. yasunagai and K. amamiensis.