Re-evaluation of endogenous development of Eimeria bareillyi Gill, Chhabra and Lall, 1963 in water buffalo (Bubalus bubalis).

Water buffalo (Bubalus bubalis) is important for the economy of Asia, South America and parts of Europe. Coccidiosis is an important cause of neonatal mortality in livestock, including buffalo. Of more than 12 species of Eimeria in buffalo, Eimeria bareillyi is the most pathogenic. There are uncertainties concerning its asexual and sexual development. During a previously reported outbreak of fatal enteritis associated with E. bareillyi in buffaloes in the Netherlands, sections of small intestine were re-evaluated histologically and by transmission electron microscopy (TEM) to seek details of endogenous development. Profuse asexual multiplication occurred in the jejunum and ileum. Light microscopic examination revealed that parasites divided in two (probably endodyogeny) or more organisms. There were two or more generations of morphologically different merozoites; some of these observations were confirmed by TEM. Details of gametogonic development, including oocyst wall formation are provided. Schizogonic and gametogonic development described in the present study can serve as a guide for differential diagnosis of Eimeria species in histological sections of intestines of buffaloes.