Light microscopic description and histopathological effects of Eimeria sp. (Protozoa: Apicomplexa) from the freshwater fish Chrysichthys auratus

Abstract

A species of Coccidia, Eimeria was found infecting the Nile catfish Chrysichthys auratus. The parasite was found aggregated in mucosa, submucosa and connective tissue between muscle bundles of the intestine, and also in the parenchymal tissue of the liver and the pancreas. The recorded stages were the maturing oocysts, the sporogonial and gamogonial stages; no signs of merogony were recorded. This is the first Coccidian species described from Chrysichthys auratus in Egypt. Oocysts of E. chrisychthii are distinguished from other Eimeria spp. in size and shape of sporocysts, host and site of infection. Mature oocysts were spherical or subspherical, measuring 21.6-24 (22.65) um. Sporocysts measured 6.5-8.4x 6-7.2 (7.5x6.75) um. A stieda-like body was seen in some individuals. Several histopathological changes were observed in the intestine, liver and pancreas of the host as a result of eimerian infection. In many mucosal cells of the intestine, cytoplasmic vacuolations were detected, while in submucosa, there was a collection of mononuclear macrophages with very abundant brown cytoplasm and congested blood vessels. The muscle layer also was affected. The liver of the infected fish revealed cytoplasmic vacuoles and a great depletion of glycogen granules in its cells.


KEY WORDS: coccidia- Eimeria- sporogony- histopathology- catfish


Egyptian Journal of Biology Vol.3(2) 2001: 29-37