Histopathological changes induced by the digenean intestinal parasite Masenia nkomatiensis Dumbo, Dos Santos, & Avenant‐Oldewage, 2019 of the catfish Clarias gariepinus (Burchell) from Incomati Basin, Mozambique

Abstract

The intestines of 154 Clarias gariepinus were examined of which 29 were naturally infected with Masenia nkomatiensis, and of these, seven (intensity ranging from 8 to 231) were examined for pathology. Destruction of the epithelium covering the villi, detachment of epithelial cells and parts of villi were observed. Excessive mucus secretion occurred in the vicinity of the worm and catarrh was observed, indicative of an inflammatory response. The number of mucous and mast cells was higher at the attachment site than at an area 5,000 µm away and in uninfected individuals, suggesting that the parasite triggered a localized innate immune response. The number of neutrophils, basophils and lymphocytes in infected tissue was not significantly different from uninfected tissue confirming that no acquired immune response was produced against the maseniid. The caecae in the anterior part of the parasites' intestine consisted of convoluted epithelium forming invaginations or “crypts.” Contraction of the thick layer of circular muscle fibres of the caeca facilitates the movement of digested material. Observation of digested host cells and cell debris within the caecae provides further evidence that M. nkomatiensis is consuming host cells.

Stages of Granulomatous Response Against Histozoic Metazoan Parasites in Mullets (Osteichthyes: Mugilidae)

“…In the course of parasitism of luminal organs, such as the intestine, immune cells expel parasites by the local release of vesicle content at the site of parasite infection and by the stimulation of synergist mechanisms (increase in mucous production, stimulation of peristalsis, etc.) [ 84 , 85 , 86 , 87 ]. On the contrary, in parenchymal organs where a proper elimination of the parasite is not achievable, encapsulation is the mechanism employed to limit parasite spread [ 10 , 11 , 37 , 88 ].…”

Parasites and the neuroendocrine control of fish intestinal function: an ancient struggle between pathogens and host

“…There are several studies on the histopathological effects of trematode infection in fish intestine (Sayyaf Dezfuli et al ., 2018 a , 2021 a ; Dumbo and Avenant-Oldewage, 2019). In comparison with other helminth taxa, such as Acanthocephala, the shallow attachment of trematodes to the intestinal mucosa (Fig.…”

Oxidative stress biomarkers in the African sharptooth catfish, Clarias gariepinus, associated with infections by adult digeneans and water quality

“…Two digenean species parasitize the intestine of C. gariepinus ; namely, Masenia nkomatiensis Dumbo, Dos Santos & Avenant-Oldewage (2019) (Cephalogonimidae) and Glossidium pedatum Looss, 1899 ( incertae sedis ). These species have been recorded only in Africa, infecting the intestines of clariid fishes ( Dumbo et al, 2019a , b ).…”

“…The life cycle of both parasite species is unknown, however, in general, the life cycle of digeneans include various stages namely, miracidia, sporocysts, rediae, cercariae and metacercariae that develop in multiple hosts such as molluscs (first obligate intermediate host), crustaceans and vertebrates ( Poulin and Cribb, 2002 ). Dumbo and Avenant-Oldewage (2019) reported immune and pathological changes in the intestine of C. gariepinus caused by adults of M. nkomatiensis , yet a similar study is not available for G. pedatum . To the best of our knowledge, no studies have dealt with the effect of both, digenean parasites and physico-chemical water quality parameters on selected physiological biomarkers in this fish.…”