In vivo Action of the Anticoccidial Diclazuril (Clinacox[registered]) on the Developmental Stages of Eimeria tenella: An Ultrastructural Evaluation

Abstract

A single 5-mg/kg oral dose of diclazuril affected both the asexual and sexual development of Eimeria tenella in experimentally inoculated chickens. In second-generation schizonts, early growth and nuclear divisions progressed normally, but a marked inhibition of merozoite formation was observed. Exogenesis of merozoites was largely prevented, whereas production of micronemes, amylopectin granules, and dense bodies and the formation of rhoptries, conoid, and pellicle continued. All these subcellular organelles accumulated, together with differentiated nuclei, within the main cytoplasmic mass. In the end, complete necrosis of the schizonts occurred. In macrogamonts, dilation of the rough endoplasmic reticulum around type II wall-forming bodies, fusion of type II wall-forming body contents, disturbance of the normal parallel arrangement of rough endoplasmic reticulum, and disruption of row formation of amylopectin granules became evident. In the microgamonts, normal evagination of microgametes was prevented; the flagellar complex formed within the main cytoplasmic mass and the differentiated nuclei remained present within the parasite body. The macro- and microgamonts also ended up in a stage of complete necrosis. These data indicate that diclazuril treatment primarily affects the normal differentiation of the respective endogenous stages during parasite development. This leads to complete degeneration of schizonts and gamonts indicating the lethal effect of this new anticoccidial compound.

Anticoccidial effect of halofuginone hydrobromide against Eimeria tenella with associated histology

“…Similar phenomenon has been observed in other studies (Verheyen et al 1988(Verheyen et al , 1989McDougald and Galloway 1977;Taylor et al 2003). It may be that vacuolation and degeneration is a common phenotype in parasites after drug treatment.…”

Coccidiosis in poultry: anticoccidial products, vaccines and other prevention strategies

“…Diclazuril is a nucleoside analogue thought to be involved in nucleic acid synthesis, possibly affecting later phases of coccidia differentiation (Verheyen et al 1988). It has been shown to affect parasite wall synthesis resulting in the formation of an abnormally thickened, incomplete oocyst wall and zygote necrosis in both E. brunetti and E. maxima (Verheyen et al 1989).…”

Actin-depolymerizing factor of second-generation merozoite in Eimeria tenella: clone, prokaryotic expression, and diclazuril-induced mRNA expression

“…Studies have demonstrated that this compound has a broad spectrum activity against all pathogenic Eimeria species in chickens. In E. tenella, detailed histological, clinical, and ultrastructural studies have shown that diclazuril, given in a single oral dose at different periods after inoculation, was fully effective against asexual as well as sexual stages Verheyen et al 1988). It was found that treatment with diclazuril downregulated mz-ADF mRNA expression by 63.86% in the present study.…”

“…Diclazuril, a benzeneacetonitrile anticoccidial, has potent activity against the asexual and sexual stages of E. tenella development (Xie et al 1991;Maes et al 1988;Verheyen et al 1988;Nodeh et al 2008). However, the exact mechanisms that drive inhibition of diclazuril in second-generation merozoite remain incompletely understood.…”