title: Tetrahymena sp. infection in guppies, Poecilia reticulata Peters: parasite characterization and pathology of infected fish.
abstract: Tetrahymena sp. infection was diagnosed in guppies imported from Singapore. The parasite was isolated (Tet-NI) and optimally cultured in vitro in RM-9 medium. Cytological analyses [silver-staining and scanning electron microscopy (SEM)] revealed a pyriform-shaped, 64 x 41-microm holotrich ciliate without caudal cilium, containing a macro-nucleus (18.25 x 16.83 microm) and micro-nucleus (5.73 x 5.40 microm). Wet-mount examination and histological analyses of fish exposed to the parasite by co-habitation, immersion and infection by i.p. (intra-peritoneal) and i.m. (intra-muscular) injection revealed numerous ciliates on the skin, and in the gill and caudal fin blood vessels. Ciliates surrounded internal organs, the peri-orbital region of the eye, and were observed inside developing guppy embryos. Some muscle necrosis was associated with infection, but little or no inflammatory response. Immersion, co-habitation and i.m. injection caused relatively high infection rates and levels in the skin and tail, and lower infection in the gill blood vessels and internal organs; i.p. injection caused higher infection in the gill blood vessels and internal organs. Co-habited fish had relatively high infection levels in the hind-gut sub-mucosa. This is the first report of controlled systemic infection by Tetrahymena sp.
authors.affiliation: The French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
authors.forename: M P
authors.initials: MP
authors.lastname: Leibowitz
authors.forename: D
authors.initials: D
authors.lastname: Zilberg
mesh_terms: D000818:Animals; D016770:Ciliophora Infections / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology / Q000469:parasitology*; D006651:Histocytochemistry / Q000662:veterinary; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D011036:Poecilia; D012876:Skin Diseases, Parasitic / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D013768:Tetrahymena / Q000276:immunology* / Q000648:ultrastructure