Some pathophysiological insights into ovarian infestation by Myxobolus sp. (Myxozoa: Myxosporea) in Clarias gariepinus (Clariids: Silurids) from Bénin (West Africa)

International audienceMature female specimens of the catfish Clarias gariepinus originating from Ouémé River (Benin) were investigated into ovarian myxozoan parasites. Spores of Myxobolus sp. (Myxozoa: Myxosporea) were found encrusted in the whitish color oocytes which present fat dot aspect in the gonads. The pathological investigation by electron microscopy revealed that maturation and multiplication of spores induced lytic action, deformation and dysfunction of the oocyte internal structures. No host inflammatory reaction was observed, while yolk, lipid, mitochondria, and other oocyte components were degenerated inducing empty area in the oocyte and could lead to castration in case of wide infestation. The mean prevalence was 19.79 %. No significant difference was observed within seasonal prevalence (χ2 = 1.771; df = 3; p > 0.05). Though the host length classes ranging from 35 to 39 cm and 40 to 45 cm were more infected, difference was not significant (χ2 = 2.273; df = 4; p > 0.05) within them. The spores are ovoid in shape with two polar capsules which are equal in size, pyriform, and converging in anterior part of spore with four to five polar filament turns. Spore body are (11.47 ± 0.67) × (8.19 ± 0.52) μm length by width while polar capsule size are (4.24 ± 0.25) × (3.07 ± 0.28) μm and located in the first third portion of the spore. The molecular approaches are still running for accurate identification of this parasite

Histopathological and ultrastructural studies of a Henneguya species (Myxozoa: Myxosporea) infesting the intestine of Clarias gariepinus from Benin (West Africa)

International audienceFish culture is the best alternative to fill the gap between natural fish catches and estimated needs of populations in animal protein consumption. In West Africa, this goal required to have suitable fishes for aquaculture which are Clariidae and Tilapia. Clarias gariepinus (Clariidae) fetches a higher price than tilapias as it can be sold alive at the market but a high infestation by Henneguya leads to decrease this commercial value. Those reasons lead us to perform studies on seasonal variations, histopathological aspects and life cycle of Henneguya sp. infecting the intestine of C. gariepinus using light and electron microscope. From November 2011 to December 2012, 339 specimens were collected from Ouémé River (Benin) and examined. An overall prevalence of 7.37 % was recorded for plasmodia of Henneguya sp. Parasite occurrence did not vary significantly between seasons (χ2 = 12.235; df = 3; p > 0.05), nor sexes (χ2 = 2.992; df = 7; p > 0.05) while differences were significant between classes of weight (χ2 = 39.929; df = 5; p < 0.05). The highest prevalence was recorded in host ranging from 300 to 374 g. Histopathological analysis showed that the mass continuous development of the plasmodium produced thickening of the intestine wall and compressed neighboring tissues and destroyed villi and smooth muscle layers. The stages of the parasite development including sporogenesis, capsulogenesis, and valvogenesis were asynchronous. Investigations are still running by molecular approaches in order to identify accurately this species