Synonym: Eimeria ah-sa-ta Honess, 1942.
Hosts: Sheep, Rocky Mountain bighorn sheep.
Location: Unknown. Oocysts found in feces.
Geographic Distribution: North America (Wyoming, Alabama).
Morphology: The oocysts are ellipsoidal and faint pink. The oocyst wall is faint straw-colored and lined by a membrane. A micropyle and micropylar cap are present. Oocysts from the bighorn sheep are 30 to 40 by 20 to 30 u with a mean of 32.7 by 23.7 u; their length-width ratio is 1.1 to 1.8 with a mean of 1.40; the micropylar cap is 0.4 to 4.2 u high and 2.1 to 12.5 u wide with a mean of 2.1 by 7.5 u. Oocysts from domestic sheep are 29 to 37 by 17 to 28 u with a mean of 33.4 by 22.6 jut; their length-width ratio is 1.2 to 1.8 with a mean of 1.48; the micropylar cap is 1.7 to 4.2 u high and 5.9 to 13.4 u wide with a mean of 3.0 by 8.4 u. An oocyst residuum is present in some oocysts. Oocyst polar (?) granules are almost always present. The sporocysts are 15.4 by 7.8 u and have a sporocyst residuum.
This species is difficult to distinguish from E. arloingi, and Morgan and Hawkins (1952) and Lotze (1953) considered it of doubtful validity. However, Smith, Davis and Bowman (1960) rediscovered it in Alabama and confirmed its distinctiveness.
Life Cycle: Unknown. The prepatent period is 18 to 20 days according to Smith, Davis and Bowman (1960).
Pathogenesis: Smith, Davis and Bowman (1960) considered this the most pathogenic of all sheep coccidia. They produced fatal infections in 4 out of 9 lambs 1 to 3 months old by feeding 100,000 oocysts. The intestines of infected lambs had thickened, somewhat edematous areas in the upper part. The Peyer's patches and the last 8 to 10 inches of the small intestine above the ileocecal valve were inflamed.