Morphological characterization and first molecular identification of the eleven Eimeria species that infect sheep from Mexico.

Within livestock production, enteric diseases play an important role, since they cause severe economic losses due to mortality, growth depression, and reduction in the conversion rate. Coccidiosis caused by Eimeria spp. is a parasitic disease of high morbidity that affects various animal species, including sheep. In sheep, eleven species of Eimeria have been identified mainly through microscopical identification of the oocysts; however, this technique has certain limitations that make it difficult to identify the different Eimeria species. The objective of the present study was to morphologically identify the eleven species of Eimeria that infect sheep in the southeastern region of the State of Mexico, as well as obtain the partial sequence of the ITS-1 rRNA region of each species and analyze it phylogenetically. A total of 412 samples were collected from the 13 municipalities that comprise the region I of the State of Mexico, out of which, 40 had approximately 80% of a single Eimeria species. Among these, the eleven Eimeria species reported in sheep were identified. The phylogenetic analysis showed that the species reported in this study are associated with those reported in rabbits, bovines, and birds. It is suggested that the phylogenetic division of sheep in two clades may be associated with the presence or absence of the residual body. It is proposed that the present methodology can be used effectively for diagnosis and to obtain information about the epidemiology of ovine coccidial infection. The results obtained in this study constitute the first report of the ITS-1 region of the eleven Eimeria species that infect sheep worldwide.