Infecção das brânquias de tilápia do Nilo (Oreochromis niloticus) por Myxosporea / Infection of the gills of Nile tilapia (Oreochromis niloticus) by Myxosporea

Neste estudo, 85 tilápias do Nilo (Oreochromis niloticus Linnaeus, 1758) foram coletadas em um lago de pesca recreativa (n = 35) e no lago do parque do Ibirapuera (n = 50), ambos localizados na cidade de São Paulo. Após a eutanásia, as brânquias dos peixes foram examinadas a fresco e por técnicas histológicas para identificar mixosporídeos. Foram observados mixosporídeos somente nos peixes capturados no lago de pesca recreativa com prevalência de 45,7% (16/35). Os esporos de Henneguya sp. foram encontrados em esfregaços a fresco (11,4%, 4/35). A prevalência de Myxobolus sp. foi de 34,3% (12/35), sendo os plasmódios deste gênero identificados de acordo com a localização nas brânquias, no epitélio (75%, 9/12), nos vasos sanguíneos (16,2%, 2/12), e na musculatura branquial (0,8%, 1/12). A presença de mixosporídeos estava relacionada com hiperplasia epitelial, fusão das lamelas, hiperplasia de células mucosas, reação inflamatória e outras alterações patológicas. Assim conclui-se que as prevalências de Myxobolus sp. e Henneguya sp. nas brânquias de O. niloticus foram altas e estavam associadas à lesões histopatológicas significantes, o que evidencia a importância desses cnidários patogênicos para as culturas peixes.(AU)

In this study, 85 Nile tilapia (Oreochromis niloticus Linnaeus, 1758) were collected in recreational fishing lake (n=35) and Lake Ibirapuera Park (n=50), both located in the city of São Paulo. After euthanasia, the fish gills were examined fresh and after histological techniques for the presence of myxosporea. Myxosporeans were observed only in recreational fishing lake with a prevalence of 45.7% (16/35). Henneguya sp. (11.4%, 4/35) and Myxobolus sp. (34.3%, 12/35) were myxosporeans observed in this study. Spores of Henneguya sp. were found in smears fresh gills. The plasmodium of Myxobolus found was of the types epithelial (75%, 9/12), vascular (16.2%, 2/12), and muscle, muscle located in the gills (0.8%; 1/12). The presence of myxosporea was related to epithelial hyperplasia, fusion of lamellae, hyperplasia of mucous cells, inflammation and other pathological changes. Thus it is concluded that prevalence of Myxobolus sp. and Henneguya sp. in gills of O. niloticus was high and was associated with significant histopathological lesions, which highlights the importance of these protozoa to fish cultures.(AU)

Myxozoan infection in the muscle layer of the intestine of Rhamdia quelen from the Amazon River Basin, Brazil / Infecção por Myxozoa na camada muscular intestinal do Rhamdia quelen da Bacia do Rio Amazonas, Brasil

ABSTRACT: The present study investigated the morphology and pathology associated with the occurrence of cysts caused by Myxobolus sp. in the intestine of the silver catfish Rhamdia quelen . Comparisons with the other Myxobolus species that infect the intestines of cyprinids and siluriforms revealed that the pyriform spores of Myxobolus sp. are similar in shape to those described previously in M. miyairii, M. duodenalis and M. cunhai, but different in size. Morphometric analyses revealed that mature spores of Myxobolus sp. (10.9 x 5.1μm) are smaller than those of most species except M. cunhai (10.0 x 5.0μm), which has been described infecting the Brazilian catfish Pimelodus clarias , although the spores differ morphologically in relation to the shape of the polar capsules. Further research is necessary in order to clarify the taxonomic and phylogenetic relationships among these congeneric species.

RESUMO: O presente estudo investigou a morfologia e patologia associada com a ocorrência de cistos de Myxobolus sp. no intestino do peixe siluriforme Rhamdia quelen . Comparações com outras espécies de Myxobolus que têm infectado intestinos de carpas e bagres de água doce demonstraram que os esporos piriformes de Myxobolus sp. são similares no formato dos anteriormente descritos para M. miyairii, M. duodenalis e M. cunhai , diferindo, no entanto, quanto ao tamanho. As análises morfométricas revelaram que os esporos maduros de Myxobolus sp. (10,9 x 5,1μm) são menores do que os da maioria das espécies, exceto para M. cunhai (10,0 x 5,0μm), que foi descrito infectando o bagre brasileiro Clarias pimelodus , embora os esporos sejam diferentes morfologicamente em relação à forma das cápsulas polares. Futuras pesquisas são necessárias para esclarecer as relações taxonômicas e filogenéticas entre espécies congêneres.

Infection of the heart of Pimelodus ornatus (Teleostei, Pimelodidae), by Myxobolus sp. (Myxozoa, Myxobolidae) / Infecção do tecido cardíaco de Pimelodus ornatus (Teleostei, Pimelodidae), por Myxobolus sp. (Myxozoa, Myxobolidae)

The phylum Myxozoa Grassé, 1970, consists of a heterogenous group of around 50 genera that are worldwide disseminated in a wide variety of aquatic media. In the present study, 43 specimens of Pimelodus ornatus were collected from an adjacent area to the Cachoeira do Arari municipality on Marajó Island, in the Brazilian state of Pará, in 2013. Macroscopic analysis showed the presence of whitened plasmodia located in the cardiac muscle and also in the region between the bulbus arteriosus and atrium cordis. Microscopic analysis on the parasitized tissues revealed spores that were typically piriform, with the anterior portion slightly narrower than the posterior end. The spore valves were symmetrical. The present species is placed in the genus Myxobolus Butschli, 1882, because of the presence of a pair of equal polar capsules in each spore. The prevalence of parasitism observed was 13.9% (6/43). This research note reports the first occurrence of Myxobolus as a parasite of the heart in the teleostean fish P. ornatus in the Amazon region and confirms the occurrence of secondary myocarditis in this fish, caused by parasitism by Myxobolus sp. The rarity of this parasitic species of Myxobolus at this tissue site, associated with other spore morphology characteristics in the fish, suggests that it is an undescribed species.

O filo Myxozoa Grassé, 1970, consiste em um grupo heterogêneo de cerca de 50 gêneros que são disseminados em todo o mundo em uma grande variedade de meios aquáticos. No presente estudo, quarenta e três espécimes de Pimelodus ornatus foram coletados a partir de uma área adjacente à cidade de Cachoeira do Arari, na Ilha do Marajó, no Estado do Pará, em 2013. À análise macroscópica verificou-se a presença de plasmódios esbranquiçados, localizados no músculo cardíaco e também na região entre o bulbus arteriosus e o atrium cordis. A análise microscópica dos tecidos parasitados revelou esporos que eram tipicamente piriformes, com a porção anterior um pouco mais estreita do que a extremidade posterior, sendo suas válvulas simétricas. A prevalência do parasitismo observada foi de 13,9% (6/43). Esta nota de pesquisa relata a primeira ocorrência de Myxobolus como um parasita do coração no peixe teleósteo P. ornatus, na Região Amazônica e, confirma a ocorrência de miocardite secundária causada por esse parasitismo. A raridade da ocorrência de Myxobolus sp. neste tecido, associado a outras características morfológicas dos esporos no peixe, sugere que é uma espécie não descrita.

Morphologic and Genetic Evidence for Mixed Infection with Two Myxobolus Species (Myxozoa: Myxobolidae) in Gray Mullets, Mugil cephalus, from Korean Waters

The present study was performed to trace the decisive evidence for mixed infection of 2 Myxobolus species, M. episquamalis and Myxobolus sp., in the gray mullet, Mugil cephalus, from Korean waters. Mullets with whitish cyst-like plasmodia on their scales were collected near a sewage plant in Yeosu, southern part of Korea, in 2009. The cysts were mainly located on scales and also found in the intestine. The spores from scales were oval in a frontal view, tapering anteriorly to a blunt apex, and measured 7.2 microm (5.8-8.0) in length and 5.3 microm (4.7-6.1) in width. Two polar capsules were pyriform and extended over the anterior half of the spore, measuring 3.5 microm (2.3-4.8) in length and 2.0 microm (1.5-2.2) in width. In contrast, the spores from the intestine were ellipsoidal, 10.4 microm (9.0-11.9) in length and 8.4 microm (7.3-10.1) in width. The polar capsules were pyriform but did not extend over the anterior half of the spore, 3.7 microm (2.5-4.5) in length and 2.2 microm (1.8-2.9) in width. The nucleotide sequences of the 18S rDNA gene of the 2 myxosporean spores from scales and intestine showed 88.1% identity to each other and 100% identity with M. episquamalis and 94.5% identity with M. spinacurvatura from mullet, respectively. By the above findings, it is first confirmed that mullets from the Korean water are infected with 2 myxosporean species, M. episquamalis and Myxobolus sp.

Myxosporidiosis in intensively-reared Piaractus mesopotamicus: Histopathological diagnosis by means of Ziehl-Neelsen staining / Mixosporidiose em Piaractus mesopotamicus de criação intensiva: diagnóstico histopatológico pela coloração Ziehl-Neelsen

Samples of different organs from intensively-reared Piaractus mesopotamicus were collected and processed using routine histological techniques in order to produce thin sections for staining with hematoxylin-eosin and with the Ziehl-Neelsen method. Through examination under an optical microscope, myxosporidians of the genera Henneguya sp. and Myxobolus sp. were identified, respectivelyin the gills and kidneys of P. mesopotamicus. Plasmodia with immature spores of Henneguya sp. were located along the secondary lamellae, with total length of 30.45±4.84µm and width of 3.52±0.33µm. Spores of Myxobolus sp. were located in the kidneys, with total length of 8.94±0.82µm and width of 5.59±0.39µm. Histopathological analysis of the gills showed plasmodia containing spores of Henneguya sp., at intralamellar and intravascular localities, at different stages of development. Spores of Myxobolus sp. were identified in the kidneys, in the peritubular region and in the interstices and glomerulus, surrounded by melanomacrophages. Focal hemorrhage was recorded in a few cases. Ziehl-Neelsen staining allowed to identify particular features of the spores and facilitated biometry and enabled classification in comparison with hematoxylin-eosin, thus demonstrating its usefulness for histopathological diagnosis of the parasitosis.

Amostras de diferentes órgãos de Piaractus mesopotamicus mantidos em criação intensiva foram coletadas e processadas mediante as técnicas histológicas usuais para obtenção de cortes que foram corados com hematoxilina-eosina e pelo método de Ziehl-Neelsen. Ao exame em microscopia de luz foi possível identificar mixosporídeos dos gêneros Henneguya sp. e Myxobolus sp. em brânquia e rim de P. mesopotamicus respectivamente. Plasmódios com esporos imaturos de Henneguya sp. foram localizados ao longo das lamelas secundárias e mensurados (comprimento total 30,45±4,84µm e largura 3,52±0,33µm) e no rim esporos de Myxobolus sp. (comprimento total 8,94±0,82µm e largura 5,59±0,39µm). Na análise histopatológica das brânquias observaram-se plasmódios contendo esporos de Henneguya sp., com localização intralamelar e intravascular, em diferentes estágios de desenvolvimento. No rim identificaram-se esporos de Myxobolus sp., na região peritubular e no interstício e glomérulo, circundados por melanomacrófagos. Em poucos casos foi registrada hemorragia focal. O uso da coloração de Ziehl-Neelsen permitiu identificar particularidades dos esporos, facilitou sua biometria e classificação em comparação com a hematoxilina-eosina, demonstrando sua utilidade no diagnóstico histopatológico da referida parasitose.