Pathogenicity and ultrastructural pathology of Eimeria debliecki (Douwes, 1921) in experimentally infected pigs.

It was confirmed, after experimental infection of 24 weaned pigs with different doses (200,000 and 4 mil.) of Eimeria debliecki oocysts that the developmental cycle of E. debliecki occurs in the anterior jejunum and after a high dose of oocysts also in the duodenum and anterior parts of the middle jejunum. Pathological changes characterized by a light atrophy of the villi, scarcely dispersed minute erosions of the epithelium in upper parts of the mucosa and an inflammatory response in the propria of the anterior jejunum were found in the area of the largest occurrence of developmental stages of E. debliecki (from 50 cm to 100 cm from the pylorus). An inflammatory infiltrate in the propria of the anterior jejunum from 3 DPI to 5 DPI contained a conspicuously large number of plasma cells with Russell bodies. Cellular changes were detected only in enterocytes with developmental stages of E. debliecki. Changes of the microvillous zone were observed in infected enterocytes; dilated mitochondria, free ribosomes and an increased number of residual bodies were found in the cytoplasm of enterocytes. The degree of the cellular changes of enterocytes was dependent on the maturity of the developmental stage of E. debliecki. Based on pathological changes observed by the use of light and electron microscopy, the coccidium E. debliecki is considered to be pathogenic for weaned pigs in spite it does not provoke a clinical infection.