Identification of sheep eimerian parasites, Eimeria crandallis and Eimeria faurei, employing microscopic and molecular tools

Coccidiosis, caused by apicomplexan Eimeria species, is a protozoan disease that affects various species of wild and domestic animals. However, data available on Eimeria diversity in ruminants in Saudi Arabia is meagre. Therefore, this study was designed to investigate some eimerian parasites infecting sheep (Sawakni and Harrie breeds) using microscopy and molecular methods for the first time in Saudi Arabia. Twenty-four fecal samples were collected from sheep farms. Based on the floatation technique, eimerian oocysts were observed in 8 of the 24 (33.33%) fecal samples. The coccidian-positive samples were subjected to fecal culture in a shallow layer of 2.5% potassium dichromate (K2Cr2O7). Detected eimerian oocysts were described micromorphometrically as the basis for traditional oocyst identification. Morphologically, the sporulated oocysts were similar to those of sheep eimerian parasies; Eimeria faurei and Eimeria crandallis. PCR products from the two eimerian species detected from Sawakni and Harrie breeds were sequenced and were found to be distinct from each other with mutations at five positions. One of them clustered with E. crandallis with 99.8%-100% identity with sequences available in GenBank. E. crandallis was obtained from two Sawakni sheep and two Harrie sheep. The other sequences grouped with E. faurei with 99.8% identity with the only sequences available in GenBank. E. crandallis was detected from both Sawakni and Harrie breeds whereas E. faurei was detected only from Sawakni sheep. The findings of this study have implications for the importance of morphometric identification with advanced molecular tools to confirm the identities of sheep Eimeria species and to address the taxonomic study of this eimeriid parasite at the species level.