Coccidia (Protozoa : Eimeriidae) of Domestic Sheep in the United States, with Descriptions of the Sporulated Oocysts of Six Species

Abstract

Detailed descriptions are given of the sporulated oocysts of the following coccidia from domestic sheep: Eimeria granulosa Christensen, 1938; E. intricata Spiegl, 1925; E. ninakohlyakimovae Yakimoff and Rastegaieff, 1930; E. pallida Christensen, 1938; E. punctata Landers, 1955; and Isospora sp. This is the first report of Isospora from sheep; it resembles I. lacazei of English sparrows, and may not be a true parasite of sheep. In a survey of 153 apparently healthy sheep, mostly from Illinois, 69% were found to have coccidian oocysts in their feces; 24% had E. ahsata, 53% had E. arloingi, 24% had E. crandallis, 6% had E. faurei, 4% had E. granulosa, 7% had E. intricata, 1% had E. ninakohlyakimovae, 6% had E. pallida, 5% had E. parva, 1% had E. punctata, and 1% had Isospora sp. Although coccidia are important parasites of domestic sheep and many papers have been written on them, their speciation, morphologic features, and life cycles are surprisingly poorly known. The literature on sheep coccidia has been reviewed by Becker (1934), Levine (1961), Levine et al. (1962), and Levine, Ivens, and Fritz (1962), and the details will not be repeated here. Moussu and Marotel (1902) named the first ovine species, Eimeria faurei, and described it briefly. At first it was thought that all coccidia of sheep belonged to this species, but later it was recognized that these animals were hosts to a number of Received for publication 21 June 1963. * Present address: College of Veterinary Science, Mhow, Madhya Pradesh, India. The material presented here is taken from a thesis submitted to the University of Illinois in partial fulfillment of the requirements for the Master of Science degree in Veterinary Medical Science under the direction of Dr. Norman D. Levine, to whom the author expresses his deep sense of gratitude. The assistance of Drs. M. F. Hansen of Kansas State University, George W. Kelley of the University of Nebraska, and Ferron L. Andersen of Utah State University in supplying sheep fecal samples from their respective states and of Dr. M. E. Mansfield for supplying fecal samples from Dixon Springs Experiment Station, University of Illinois, is acknowledged. Mr. Shah was a student at the University of Illinois under a cooperative program with the Agency for International Development, U. S. Department of State. species. Baloz t (1932a, b, c) and Christensen (1938), among others, did significant research on the sheep coccidia. Becker (1956) and Pellerdy (1956) published checklists of the species. Additional references are given by Shah (1963). At present, ten or eleven species of Eimeria are recognized as occurring in sheep (Levine, 1961): E. ahsata, E. arloingi, E. crandallis, E. faurei, E. gilruthi, E. granulosa, E. intricata (which may be a synonym of E. gilruthi), E. ninakohlyakimovae, E. pallida, E. parva, and E. punctata. However, there is considerable uncertainty regarding the identification of most of these species, primarily because complete descriptions of their sporulated oocysts are la king. Christensen (1938), for instance, described only the unsporulated oocysts of the seven species he discussed, and he illustrated the sporulated oocysts of only two, E. pallida and E. granulosa. Levine et al. (1962) gave a detailed description of the sporulated oocysts of Eimeria ahsata from sheep, and Kamalapur (1961) did the same for E. ahsata, E. arloingi, E. crandallis, E. faurei, and E. parva from sheep. The objectives of the present study were to prepare detailed descriptions of the sporulated oocysts of all the other known coccidia of sheep and to determine the prevalence of all species in Illinois and, to some extent, other parts of the