Cryptosporidium scophthalmi n. sp. (Apicomplexa: Cryptosporidiidae) from cultured turbot Scophthalmus maximus. Light and electron microscope description and histopathological study

• Published in: Diseases of Aquatic Organisms
• Main Authors: Álvarez-Pellitero, Mª del Pilar, Quiroga, María Isabel, Sitjà-Bobadilla, Ariadna, Redondo, Mª José, Palenzuela, Oswaldo, Padrós, Francesc, Vázquez, Sonia, Nieto, José M.
• Other Authors: European Commission, Ministerio de Ciencia y Tecnología (España), Stolt Sea Farm
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Inter Research 2004
• Subjects: Aquaculture; Coccidia; Cryptosporidium scophthalmi n. sp; Histopathology; Teleostei; Ultrastructure; Scophthalmus maximus; Turbot
• Online Access: http://hdl.handle.net/10261/253764; https://doi.org/10.3354/dao062133; https://doi.org/10.13039/501100000780; https://doi.org/10.13039/501100006280

Cryptosporidium scophthalmi n. sp. is described from the turbot Scophthalmus maximus L., sampled from different farms on the coast of NW Spain. The parasite was found mainly in the intestinal epithelium and very seldom in the stomach. Oocysts were almost spherical, with 4 naked sporozoites and a residuum, and measured 3.7-5.03 x 3.03-4.69 μm (mean 4.44 x 3.91) (shape index 1.05-1.34, mean 1.14). Sporulation was endogenous, as fully sporulated oocysts were found within the intestinal epithelium, lumen and faeces. Merogonial and gamogonial stages were in the typical extracytoplasmic position, whereas sporogonial stages were deep within the epithelium. Oocysts and other stages of C. scophthalmi comply with most of the diagnostic features of the genus Cryptosporidium, but differ from all hitherto described species. Ultrastructural features, including the characteristic feeding organelle, were mainly comparable with those of other Cryptosporidium species. Mitochondria were frequently observed in sporozoites. Infection prevalence was very variable, and juvenile fish were most frequently and intensively parasitised. External clinical signs were not detected, although some fish showed intestinal distension at necropsy. The marked histopathological damage occurring in severe infection includes distension of epithelial cells by large vacuoles, containing clusters of oocysts, and can lead to sloughing of epithelial cell remnants and oocysts or even detachment of intestinal mucosa. An inflammatory reaction involving leucocyte infiltration was sometimes observed. Funding for this study was provided by the EU and the Spanish Ministerio de Ciencia y Tecnología through research grants FEDER 1FD97-0679 and AGL2001- 2241. Additional support was obtained from Stolt Sea Farm S. A. We are thankful to technical services at the Universities of Barcelona and Valencia, to J. Monfort from IATS, and to M. C. Carreira Valle from the School of Veterinary Medicine of Lugo (University of Santiago) for assistance in processing electron and ...