Spironucleosis (Hexamitiasis, Hexamitosis) in the Ring-Necked Pheasant (Phasianus colchicus): Detection of Cysts and Description of Spironucleus meleagridis in Stained Smears

Abstract Trophozoites and cysts of Spironucleus (Hexamita) meleagridis were detected in the intestinal fluid and mucus of pheasant poults with spironucleosis (hexamitiasis, hexamitosis) following staining with Heidenhain iron hematoxylin (HIH) and the Romanowsky-type stain Hemacolor®. Their morphology was consistent with that of flagellates of the genus Spironucleus, and bright-field morphologic observations were confirmed by transmission electron microscopy. Cysts occurred mostly within intestinal mucus, which was firmly compressed between microscope slides prior to staining. The internal structures of cysts were similar to those of trophozoites, allowing them to be confidently recognized. Hemacolor provided differential color staining of trophozoites and cysts, allowing accurate identification of S. meleagridis life cycle stages, even in smears in which there was heavy background staining. While HIH often produced clearer and more detailed staining of protozoan structures, in the context of a diagnostic...