Protozoan infections in farmed fish from Brazil: diagnosis and pathogenesis

Abstract

The Phylum Protozoa brings together several organisms evolutionarily different that may act as ecto or endoparasites of fishes over the world being responsible for diseases, which, in turn, may lead to economical and social impacts in different countries. Apart from the recent advances for the diagnosis of fish diseases in Brazil, little is known on the protozoan parasites and their relationship with environment and host. This revision presents the most important protozoan parasites found in farmed fish from Brazil, not only with emphasis on its diagnosis, biology, transmission and host-parasite relationship, but also on some information that may be useful to researchers in determining the correct diagnosis in fish farms.Keywords: Fish parasites, disease, ciliate, dinoflagellate, pathogenicity. ResumoO filo Protozoa reúne diversos organismos evolutivamente distintos que podem atuar como ecto ou endoparasitos de peixes em todo o mundo, sendo responsáveis por doenças as quais, por sua vez, podem ocasionar impactos econômico e social nos diferentes países. Apesar dos recentes avanços no campo de diagnóstico de doenças em peixes no Brasil, ainda pouco se conhece sobre a fauna de protozoários parasitos de peixes e suas relações com o ambiente e hospedeiro. Esta revisão apresenta os mais importantes protozoários parasitos encontrados em peixes cultivados no Brasil, não apenas com ênfase no seu diagnóstico, biologia, transmissão e relação hospedeiro-parasito, mas também algumas informações que podem ser úteis para pesquisadores para o correto diagnóstico em pisciculturas.Palavras-chave: Parasitos de peixes, enfermidade, ciliado, dinoflagelado, patogenicidade.

Parasites of Nile Tilapia larvae Oreochromis niloticus (Pisces: Cichlidae) in concrete ponds in Guanacaste, Northern Costa Rica

“…(Epistylis genus) showed prevalence differences between seasons (Martins, Cardoso, Marchiori, & Benites, 2015), showing high values in rainy season, which agrees with our report. Probably, this protozoa has an optimal reproduction at lower temperature with hypoxic water conditions.…”

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

“…colonies in fish was first described by Hazen et al (1978), who registered Aeromonas hydrophila as the primary causative agent of red-sore disease in North American cichlid. In the present study, abundant bacterial microflora was associated to the peduncle surface of Epistylis sp., and most of the pathological changes may result from bacterial proteolytic enzymes (Martins et al, 2015). Recently, Valladão et al (2015) have also proposed that tissue damage may have occurred due to the action of immune cells at the site of parasitism, because these cells are provided with hydrolytic molecules capable of causing cell damage.…”

“…In addition, the bacterial colonization of the peduncle of these protozoans contributes to aggravate the injuries on host tissues, characterizing Epistylis sp. as an agent of diseases of mixed etiology, considered important infirmities for farmed fish (Hazen et al, 1978;Martins et al, 2015).…”

Parasitological assessment in the hybrid surubim (Pseudoplatystoma reticulatum x P. corruscans), with uncommon occurrence of Monogenea parasites

“…The proliferation of I. multifiliis is strongly related to periods of lower temperatures in tropical regions (MARTINS et al, 2015) coinciding with the highest water transparency, higher levels of dissolved oxygen and orthophosphate. Crustaceans were also observed in periods of low temperature.…”

“…In order to consolidate the production of this fish more studies are needed to understand the host/parasite/environment relationship to improve the knowledge of diseases responsible for economic losses (MARTINS et al, 2015). This study aimed to contribute to the knowledge of the parasite fauna in the hybrid catfish (P. reticulatum female x P. corruscans male) and to establish the host/parasite/environment relationship during the cycle of two production systems.…”