Histopathological changes in Trypanosoma danilewskyi Laveran & Mesnil, 1904 and Trypanoplasma borelli Laveran & Mesnil, 1902 infections of goldfish, Carassiw auratus (L.)

Abstract. Syringe passaged stocks of Trypanosoma danilewskyi and Trypanoplasma borelli derived from carp were used for experimental infections of goldfish. Infections of T. danilewskyi and T . borelli produced a heavy parasitaemia in the peripheral blood of goldfish and extensive tissue damage, mainly in haemopoietic organs. There was no inflammatory reaction or haemorrhage in trypanosome infected goldfish. Infection with trypanoplasms provoked more varied changes including vascular lesions and inflammatory changes. The extent of pathological changes occurring at rising and peak levels of parasitaemia could account for the high mortality (up to 100%) of the infected fish.