Infections negatively influence the production of tambaqui, and in north Brazil, the wide distribution of this parasitic disease has generated concern among fish farmers. The objective of this study was to review published literature on this pathogen. Six main online research databases were searched using the keywords “Neoechinorhynchus buttnerae”, “acantocefalose”, and “acanthocephalan fish”. Based on a set of predetermined criteria, 39 publications were selected for this review. The mechanism of pathogenic action of N. buttnerae is related to the degree of penetration of the proboscis. Infection results in histopathological and morphological changes in the host. The recurrence of the parasite in the northern region was greater twelve years after their first occurrence. The lack of specific legislation on veterinary products for aquatic animals, combined with the neglect of good management practices, and the absence of a contingency plan for the control of acanthocephalan infections have contributed to the current health situation of Colossoma macropomum northern Brazil. Additional information about the occurrence of the disease, pathogenicity, and control of acanthocephalan infections are imperative for developing a disease contingency plan in the region and research to address these should be encouraged by the sector.
The aim of the present study was to assess the use of sodium chloride (NaCl) against monogenoid infestations in pirarucu (Arapaima gigas). Two assays were conducted with pirarucu juveniles, the rst comprising an in vitro exposure to 8; 9; 10 and 11 g.L − 1 NaCl and comparison to controls not exposed to NaCl, and the second, an in vivo exposure to NaCl at the same concentrations applied in the in vitro exposure. The best in vitro results were observed for one hour exposures at 9, 10 and 11 g.L − 1 NaCl, resulting in 60% and 100% parasite mortality, respectively. In vivo exposures to 8 and 10 g.L − 1 NaCl were 36 and 22% e cient, respectively, following two hours of exposure, with no mortality. Some dosedependent changes were observed in exposed sh, such as decreased hemoglobin and HCM values at the highest NaCl concentration compared to the other NaCl concentrations and the control group. More frequent gill tissue alterations were observed compared to the control group at the highest NaCl concentrations (10 and 11 g.L − 1 ). Decreased mean (p < 0.05) water pH values and increased mean electrical conductivity were noted compared to the control group. Our ndings suggest that NaCl exhibits low toxicity towards pirarucu and anthelmintic activity to the monogenoid Dawestrema cycloancistrium, directly in uenced by exposure time and concentration.
The egg is one of the fundamental parts of the life cycle of Neoechinorhynchus buttnerae, and this stage involves the acanthor larva. It is also the infection phase for the intermediate host. Under normal conditions, the larva inside the egg can survive for months in the environment; however, information regarding this phase of life of the parasite is scarce. In addition, there is no quantitative information about the structural composition of the parasite's body from a histological point of view. Such information is essential in order to support decisions aimed at controlling infestations by these parasites in fish farming. This study aimed to present a detailed description of the stages of embryonic development of N. buttnerae eggs, as well as a stereological evaluation of the body of adult females of the parasite. Three phases of development characterized the eggs: cell division (with four stages), formation of the internal nuclear mass (with four stages) and formation of the acanthor larva (with five stages). The ovary comprised 26.61% of the volume of the animal and most of it contained eggs (21.28%), ovarian balls (3.88%) and empty spaces (1.45%). These results are of great importance and will support future studies that seek to interrupt the life cycle of this parasite.
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