“Dourado”, Salminus maxillosus Valenciennes, 1840 (Osteichthyes, Characidae) liver histopatologic alterations caused by Neocucullanus neocucullanus Travassos, Artigas & Pereira 1828 (Nematoda)

Abstract

From August 1996 to December 1997, 293 specimens of Salminus maxillosus were captured in the Mogi-Guaçu river, at Cachoeira de Emas, municipality of Pirassununga, state of São Paulo, Brazil. The livers of 45 fishes were parasitized by Neocucullanus neocucullanus Travassos, Artigas and Pereira, 1928 (15.35% prevalence). Liver samples were fixed in Bouin and processed for paraffin inclusion. 5µm-sections were stained with ME, Mallory trichromic and submitted to Hematoxilin-contrasted PAS. Macroscopically, the parasitized livers had central and peripheral infection, sometimes perforating the stroma, allowing the cyst to be seen externally. Microscopically, and only surrounding the parasite, intense tissue disorganization, with typical active inflammatory process cells, and discrete fibrin deposition around the inflammatory focus. Juxtaposed to the parasite, there is the thin capsule with fibroblasts and collagen. The presence of leukocytes and the parasite encapsulation indicate an acute inflammatory process.