Search

Abstract The genus Dermocystidium infects a wide range of animals. The host infection often occurs through the ingestion of endospores. The diagnosis depends on wet mounts and histopathological analysis of the affected tissue. The aim of this study was to investigate the incidence of Dermocystidium sp. infection on the skin of farmed striped catfish (Pangasianodon hypophthalmus) from a fish farm located in Fortaleza, Ceará state, northeastern Brazil. From these observations, we determined that 100% of the analyzed animals were infected with Dermocystidium sp. The wet mount and histopathology of the fish lesions revealed spore-filled cysts between the dermis and epidermis, encapsulated by connective tissue. Owing to a lack of research on the parasite and its prevalence among different fish species in Brazil and the rest of the world, additional studies are required to understand their endemicity in fish farms of Brazil, and consequently develop better disease prevention methods and increase the overall productivity.

In autumn 2011 in cyprinid farms located in Iasi on the Jijia river, several infections with bacterial strains and macroscopical external cysts on the skin were diagnosedwhich developed as a result of the stress induced by biotic and abiotic factors. On the examination of the cyst contents the presence of numerous spores was observed, mostly of the Dermocystidium sp genusThe samples were taken from the common carp (Cyprinus carpio) and crucian carp (Carassius auratus gibelio) species from the fish farm as well as from the Jijia River. 35 fish were examined, all of them showing cysts, fragmentation of their dorsal fin and congestion of the gills. Histological examination of the skin showed a field of multiple dermal cysts with round light eosinophilic formations (14-16µm) containing a central refractable body similar to that reported for Dermocystidium sp. Gills samples were taken from the affected areas for the SEM examination with the purpose of evaluating not only aspects of normal morphology, but also aspects of some modifications of the affected areas as well as the presence of the etiologically incriminated bacteria Pseudomonas fluorescens. The isolates were identified through phenotypic methods. All the strains that showed mobility and oxidase-positivity were tested using API 20 NE strip. Consequently, they were taxonomically grouped into the species Pseudomonas fluorescens. The scanning electron microscope (SEM) was used for the first time in the characterization of the bacterial lesions produced by Pseudomonas strains on Cyprinus carpio and Carassius auratus gibelio gills. The diagnosis of septicemia with conditional pathogen species of Pseudomonas fluorescens was correlated with the results of the physico-chemical investigations of water and the data concerning the breeding conditions of the investigated livestock.