Experimental transmission of Sphaerospora renicola to common carp Cyprinus carpio fry

Abstract

The causative agent of renal sphaerosporosis and swimbladder inflammation was observed in specific-pathogen-free (SPF) carp Cyprinus carpio L of the year following exposure to filtered water from a pond where Sphaerospora renicola Dykova et Lom, 1982 is enzootic. SPF carp showed infected kidney tubules after contact with water filtrates containing particles c45 pm in diameter. Using a Polymon filter the operative diameter of the causative agent could be determined as being <20 pm as shown by distinct S. renicola infections in SPF carp after exposure to 20 pm filtrate. Previous reports of a direct infechon by contact with spore-releasing donor carp or feeding on spore-containing hdney hssue could not be confirmed. It is hypothesized that an actinospore component may be the causahve agent of S. renicola infections in common carp.