Chemotherapy with f umagillin and toltrazuril against kidney enlargement disease of goldfish caused by the myxosporean Hoferellus carassii

Abstract

Chemotherapy with fumagillin (antibiotic) and toltrazuril (sym. triazinone) was tested against kidney enlargement disease (KED) of goldfish, caused by the myxosporean Hoferellus carassii. In October, goldfish naturally infected with an early stage of H. carassii were fed daily medicated diets of fumagillin or toltrazuril. After 1 month, fish treated with fumagillin-0.1% or 1.0% diets never developed KED, and the prevalence of infection significantly decreased. In contrast, toltrazuril was not effective to KED. In November and January, fish with a gross sign of KED harbouring more advanced stages of H. carassii were also treated with fumagillin. Light and electromicroscopy revealed fumagillin caused fatal damages to developmental stages of H. carassii. Moreover, the infected epitherial cells were dead and fallen into the lumen, and only the basement membrane remained in the tubule after 1 to 2 weeks of treatment. Taking the seasonal development of the parasite into cosideration, an effective chemotherapy against KED is proposed. © 1990, The Japanese Society of Fish Pathology. All rights reserved.