Infection of the heart of Pimelodus ornatus (Teleostei, Pimelodidae), by Myxobolus sp. (Myxozoa, Myxobolidae)

Abstract

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.

Multiparasitism in gills of Metynnis lippincottianus from the environmental protection area of Curiaú river, Eastern Amazon

“…Myxobolus spp. parasitized 65% of gills of the fish examined, a value higher than that reported in the heart of Pimelodus ornatus, from the Arari Waterfall, which had a prevalence of 13.9% in the 43 specimens analyzed (MATOS et al, 2014). LACERDA et al (2013) explained that the discrimination of the fish parasitic fauna can be based on premise that the different biogeographic regions showed a range of possibilities for the parasitic fauna structure in the host, thus explaining the differences in parasites prevalence in their hosts.…”

Morphostructural data and phylogenetic relationships of a new cnidarian myxosporean infecting spleen of an economic and ecological important bryconid fish from Brazil

“…Among myxozoans, freshwater histozoic Myxobolus species are recognized for their strict or high host-organ/tissue specificity [5], infecting a large variety of fishes within a wide geographical range [6][7][8][9]. Regarding pathogenecity, previous studies conducted in South American freshwater fishes reported Myxobolus species to cause considerable pathological alterations such as lymphocytic meningoencephalomyelitis, myocarditis of the heart, perivascular edema in the interlamellar area and deformation and compression of capillaries of the gill lamellae [10][11][12][13].…”

Myxozoan infection in the muscle layer of the intestine of Rhamdia quelen from the Amazon River Basin, Brazil

“…For example, VELASCO et al (2012) observed inflammation in the musculature of the palate of Gobioides broussonnetii LACEPÈDE, 1800, which caused a generalized necrosis of the parasitized muscle, consistent with the presence of necrotizing myositis. MATOS et al (2014) described a discreet inflammatory reaction and multifocal degeneration of the cardiac fibers by Myxobolus sp. in Pimelodus ornatus KNER, 1858 from Marajó Island.…”