Scanning morphology, prevalence and histopathology of some acanthocephalans infecting some River Nile fish

Abstract

Acanthocephalan morphology and their adverse pathological impact on fish are of great concern. Two species of acanthocephalans were recorded from 800 samples of live freshwater fish collected randomly during 2017–2018 from Lake Nasser, Aswan, Egypt. The recovered species were identified morphologically as Acanthogyrus (Acanthosentis) tilapiae from three Tilapia spp. (Sarotherodon galilaeus, Oreochromis niloticus and Tilapia zillii) and Rhadinorhynchus niloticus from Lates niloticus. The intensity of parasitic infection and the seasonal prevalence were higher in L. niloticus than in Tilapia spp. The clinical signs and post mortem lesions of infected fish were reported. Morphological description of the detected parasites using light microscope was then confirmed by electron microscopy to amplify ambiguous details. The histopathological findings of the intestine of naturally infected fish with acanthocephalan parasites were investigated and described. The main damage caused by them is destruction of the mucosal epithelium of the villi, necrosis and degeneration of intestinal epithelial cells.

A global review of problematic and pathogenic parasites of farmed tilapia

“…tilapiae into the intestine destroys the mucosal folds, causes lacerations of the intestinal villi from the proboscis hooks and provokes severe degeneration and necrosis of the mucosal epithelium 327,481 . Other changes observed in infected tilapia include desquamation of the mucosa, interstitial oedema and enteritis 481,501,502 . Aggregated infiltration of eosinophils, fibroblasts, lymphocytes and macrophages occurs at the site of attachment in response to chronic inflammation of the tissue 481,502 .…”

“…The taxonomic assignment of this OTU as Neoechinorhynchus by Elsaied et al, 509 however, appears erroneous; Acanthogyrus ( A .) tilapiae is the only acanthocephalan reported from tilapia in Lake Nasser 502,510 . Elsaied et al 509 extracted DNA from eggs released by gravid females to the lumen of infected O .…”

“…327,481 Other changes observed in infected tilapia include desquamation of the mucosa, interstitial oedema and enteritis. 481,501,502 Aggregated infiltration of eosinophils, fibroblasts, lymphocytes and macrophages occurs at the site of attachment in response to chronic inflammation of the tissue. 481,502 Little is known about the pathological effects of adults of other acanthocephalan species in cultured tilapia, but it is likely that the submucosal lesions, loss of the mucosal layer, decreased haematocrit and red blood cell counts observed in N. (N.) quinghaiensis (syn.…”

“…tilapiae is the only acanthocephalan reported from tilapia in Lake Nasser. 502,510 Elsaied et al 509 extracted DNA from eggs released by gravid females to the lumen of infected O. niloticus, and this approach has merit for non-destructive detection and identification of all endoparasites.…”