Pathological changes induced byPomphorhynchus laevis Muller (Acanthocephala) in the gut of rainbow trout,Salmo gairdneri Richardson

Abstract

The consequences of infection of rainbow trout, Salmo gairdneri Richardson, by an acanthocephalan, Pomphorhynchus laevis Muller, have been studied using light and electron microscopy. The mucosal epithelium, of the gut adjacent to the metasoma of the worm suffered compression and abrasion. The praesoma of P. laevis penetrated the mucosal epithelium, lamina propria, stratum compactum, stratum granulosum, muscularis and serosa of the gut wall, and was invested by a fibrous capsule of inflammation tissue. This was composed of four principal cell types: eosinophilic granular cells (EGCs), type A cells, type B cells and fibroblasts. Some melanocytes and lymphocytes were also present. The role of the EGCs in the inflammation response is not known, but may not be an active one. The type A cells resembled neutrophils of other fish species, and have tentatively been placed in this category. The type B cells, with large cisternae formed by the RER, resembled plasma cells and may have been involved in a humoral response to the acanthocephalan. The integument of P. laevis did not appear to be damaged by the cells of the inflammation tissue, and it seems likely that this host response was incapable of rejecting the parasite.

Pathological manifestations of the acanthocephalan parasite, Tenuiproboscis sp. in the mangrove red snapper (Lutjanus argentimaculatus) (Forsskål, 1775), a candidate species for aquaculture from Southern India

“…The nature of the pathological changes observed in the intestinal tissues, viz. compression of mucosal epithelium at the point of attachment and the tissue damage to the various layers of the intestine is in perfect agreement with the changes described by Wanstall et al (1986) for P. laevis infection in Salmo gairdneri. George and Nadakal (1981) have also reported degeneration and necrosis of the mucosal epithelium and excessive mucus secretion in Rachycentron canadum infected with the acanthocephalan, Serrasentis nadakali.…”

“…The pathology of acanthocephalan parasites in fishes especially with reference to Pomphorhynchus laevis has been well documented (Hine and Kennedy, 1974;Mcdonough and Gleason, 1981;Wanstall et al, 1986;Dezfuli, 1991). Usually in acanthocephalan infections, pathology appears to be negligible when parasites are attached to the epithelial mucosa only but deeply embedded forms like Pomphorhynchus spp.…”

Host‐parasite interface of Neoechinorhynchus rutili (Eoacanthocephala) in naturally infected salmonids*

“…N. rutili longer than 5 mm do not often seem to change their site of attachment, as can be eoncluded from the fibrosis around their presomas. However, fibrosis around the presomas of Acanthocephalus anguillae in different hosts (Taraschewski 1988) and around those of Pomphorhynchus laevis in rainbow trout (Wanstall, Robotham & Thomas 1986) and other hosts (Taraschewski, unpublished) was more conspicuous than that described here from N. rutili. Despite extensive changes in the normal structure of the gut, the gross effects of P. laevis on its hosts are considered low when infected animals are compared to uninfected eontrols (Hine & Kennedy 1974;Wanstall et al 1986).…”

Proliferative cell nuclear antigen (PCNA) expression in the intestine of Salmo trutta trutta naturally infected with an acanthocephalan

“…MCs play an important role in responding to inflammation; their number increases in allergic reactions [49] and as a consequence of helminth infection [39,53-55]. The close association of MCs with the endothelial cells of capillaries and their presence within gill capillaries suggests that they may migrate across the endothelium [47,52,54]. Nonetheless, the intra-tissue migratory nature of MCs has been observed in the gills and intestine of fish [48,56,57].…”