An intranuclear microsporidian in lumpfish Cyclopterus lumpus

Abstract

Chronic mortalities in lumpfish Cyclopterus lumpus raised in a saltwater recirculation system were associated with the presence of an intranuclear rnicrosporidian.Morphologic changes were characterized by infdtration of lymphocyte-like cells predominantly in the renal interstitium and also in the spleen, liver, gills, stomach, pyloric caecae, heart, ovary and mesenteric fat.Affected cell nuclei contained 1 to more than 6 spherical to oval eosinophilic bodies which stained poorly with hematoxylin and eosin and Giemsa.Ultrastructurally, spores were ovoid (2.1 X 1.0 pm) with a polar tube with 11 turns.The morphology of these spores place them in the genus Enterocytozoon.These spores resemble E. salmonis in salmonids, and Microsporidia rhabdophilia in the rodlet cells of salmonids.