Host-parasite relationship during Epistylis sp. (Ciliophora: Epistylididae) infestation in farmed cichlid and pimelodid fish

Abstract

-The objective of this work was to describe the host-Epistylis sp. relationship during infestation on farmed fish. Five Nile tilapia (Oreochromis niloticus) and ten hybrid surubim catfish (Pseudoplatystoma reticulatum x P. corruscans), all diseased, were used for in vivo morphological analysis of sessile peritrichs by contrast microscopy. Fragments of infected tissues were subjected to histological processing and scanning electron microscopy. Epistylis sp. caused hemorrhagic ulcer disease, and cichlids were more prone to develop infestations throughout the body surface due to the attachment of the colonies to the scales, which did not occur with pimelodids. Multifocal granulomatous dermatitis was observed, associated with the hydropic degeneration of the epithelium and to ulcerative areas of necrosis. Microscopic examination showed the presence of bacterial microflora associated to Epistylis sp. peduncles. Therefore, this species can be considered a portal of entry for opportunistic bacteria.Index terms: Oreochromis niloticus, Pseudoplatystoma reticulatum, Pseudoplatystoma corruscans, histopathology, pathogenesis, sessile peritrich. Relação hospedeiro-parasita durante infestação por Epistylis sp. (Ciliophora: Epistylididae) em peixes ciclídeos e pimelodídeos cultivadosResumo -O objetivo deste trabalho foi descrever a relação hospedeiro-Epistylis sp. durante infestação em peixes cultivados. Foram utilizados cinco tilápias-do-nilo (Oreochromis niloticus) e dez híbridos de surubim (Pseudoplatystoma reticulatum x P. corruscans), todos parasitados, para análise morfológica in vivo de peritríquios sésseis por microscopia de contraste de fase. Fragmentos de tecidos infectados foram processados para histologia e microscopia eletrônica de varredura. Epistylis sp. causou doença ulcerativa hemorrágica, e os ciclídeos foram mais susceptíveis ao parasitismo na superfície do corpo em razão da fixação das colônias nas escamas, o que não ocorreu nos pimelodídeos. Foi observada ocorrência de dermatite granulomatosa multifocal, associada à degeneração hidrópica do epitélio e às áreas ulcerativas de necrose. O estudo microscópico mostrou a presença de bactérias associadas aos pedúnculos de Epistylis sp. Portanto, esta espécie pode ser considerada porta de entrada para bactérias oportunistas.

Protozoan parasites of freshwater ornamental fish

“…Epistyliasis is considered an emergent protozoan fish disease in Brazil for cultured fish for consumption. In this study, the prevalence was low and the injury degree was not compared to previously related (Pádua et al, 2016).…”

Association of Epistylis spp. (Ciliophora: Peritrichia) with parasitic crustaceans in farmed piava Megaleporinus obtusidens (Characiformes: Anostomidae)

“…causes injury to the integument of the Nile tilapia Oreochromis niloticus which is characterized by the presence of a subepithelial infiltrate of lymphocytes and mast cells and epithelial hyperplasia and hypertrophy (VALLADÃO et al, 2015). Microscopic lesions that are seen in the integument of cultured cichlid fish and siluriformes (catfish) in association with the cilitate Epistylis include hydropic degeneration, multifocal necrosis, proliferation of skin mucous (globet) cells, and the presence of a mixed inflammatory infiltrates composed of granulocytes and mononuclear cells (PÁDUA et al, 2016). Studies have shown that Epistylis spp.…”

“…These protozoa are often considered commensal organisms in fish farms. However, in adverse environmental conditions they can cause damage to the integument of Oreochromis niloticus (Nile tilapia) (VALLADÃO et al, 2015) and Pseudoplatystoma reticulatum (barred sorubim)/Pseudoplatystoma corruscans (spotted sorubim) hybrids (PÁDUA et al, 2016).…”

Dolops carvalhoi as a vector of Epistylis sp. between cultivated and wild specimens of Oreochromis niloticus in Brazil

“…Only one specimen of cultivated Under intensive cage fish farming conditions there is an increased discharge of nutrients into the aquatic environment (MONTANHINI & OSTRENSKY, 2015), which can lead to the proliferation of some parasites including ciliate protozoans (PÁDUA et al, 2016). The occurrence of epistyliasis in fish farms can be associated with low water quality, low oxygen concentration and improper handling such as high stock densities and incorrect feeding practices (EIRAS et al, 2012;PÁDUA et al, 2013;MARTINS et al, 2015;PÁDUA et al, 2016). Although Epistylis does not directly invade the host cells, its can cause injury to the integument of fish, characterized by the presence of epithelial hyperplasia and hypertrophy, possibly caused by constant contact with the fish skin (VALLADÃO et al, 2014).…”

“…Although Epistylis does not directly invade the host cells, its can cause injury to the integument of fish, characterized by the presence of epithelial hyperplasia and hypertrophy, possibly caused by constant contact with the fish skin (VALLADÃO et al, 2014). Additionally, can occur secondary infection associated with the presence of bacteria on the peduncle, culminating in mortality and pathological changes (PÁDUA et al, 2013;MARTINS et al, 2015;PÁDUA et al, 2016), causing major losses in South American aquaculture.…”