title: Paratrichodina africana (Ciliophora): a pathogenic gill parasite in farmed Nile tilapia.
abstract: Trichodinids are ciliated protozoa that are widely known as one of the main groups of fish parasites. The genus Trichodina presents the greatest species diversity. However, records of Paratrichodina species are scarce, and little is known about their pathogenicity in hosts. The present study provides new records of Paratrichodina africana Kazubski and El-Tantawy (1986) in Nile tilapia from South America and descriptions of pathological changes and seasonality. A total of 304 farmed fish were examined. From gill scraping, parasites were identified using Klein's nitrate impregnation method. Gill samples were fixed for histopathological analysis. Small trichodinid found in this study have a prominent blade apophysis and narrow central part and blade shape that corresponds to the characteristics of P. africana Kazubski and El-Tantawy (1986). Gill lesions were proportional to parasite intensity, in which the gill tissue was compromised in heavy infestation. Proliferative disturbances were found, including epithelial hyperplasia, desquamation, and mononuclear and eosinophilic infiltrate that culminated in necrosis. We did not observe a seasonality effect on the occurrence of P. africana. This ciliated protozoan causes compromised respiratory capacity that leads to severe gill lesions and currently is an important pathogen that afflicts intensive tilapia cultures in Brazil.
authors.affiliation: Aquaculture Center of São Paulo State University (CAUNESP), Jaboticabal, São Paulo, Brazil.
authors.forename: G M R
authors.initials: GM
authors.lastname: Valladão
authors.forename: S B
authors.initials: SB
authors.lastname: Pádua
authors.forename: S U
authors.initials: SU
authors.lastname: Gallani
authors.forename: R N
authors.initials: RN
authors.lastname: Menezes-Filho
authors.forename: J
authors.initials: J
authors.lastname: Dias-Neto
authors.forename: M L
authors.initials: ML
authors.lastname: Martins
authors.forename: M M
authors.initials: MM
authors.lastname: Ishikawa
authors.forename: F
authors.initials: F
authors.lastname: Pilarski
mesh_terms: D000818:Animals; D017756:Aquaculture; D023681:Cichlids; D016798:Ciliophora / Q000166:cytology / Q000302:isolation & purification*; D016770:Ciliophora Infections / Q000469:parasitology / Q000662:veterinary*; D005880:Gills / Q000469:parasitology*
keywords: Ciliophora; Histopathology; Tilapia; Trichodinidae