Hosts: Ox, zebu. Wilson (1931) was unable to infect pigs or goats with this species.
Location: Unknown. Oocysts found in feces.
Geographic Distribution: North America, Europe (Austria), India.
Prevalence: This species is quite common. Hasche and Todd (1959) found it in 20% of 355 cattle in Wisconsin. Supperer (1952) found it in 4% of 130 cattle in Austria. Rao and Hiregaudar (1954) considered it quite prevalent in zebu calves in Bombay. Ruiz (1959) found it in 1% of 100 adult cattle in the San Jose, Costa Rica abattoir.
Morphology: This species has been described by Wilson (1931) and Christensen (1941). The oocysts are 16 to 28 by 12 to 16 u with a mean of about 23 by 14 u. They are typically cylindrical, their sides being nearly parallel thruout their middle third, but they may vary from ellipsoidal to narrow cylinders twice as long as wide. The oocyst length-width ratio is 1.3 to 2.0 with a mean of 1.67. The oocyst wall is thin, smooth, homogeneous, transparent, colorless to slightly tinted, and presumably composed of a single layer. A micropyle is absent, altho the wall is slightly paler at one end. An oocyst residuum and polar granule are absent. A sporocyst residuum is present, but there is no sporocyst Stieda body. The sporozoites are elongate, lying lengthwise in the sporocysts and filling them. (According to Rao and Hiregaudar, 1954, the sporocysts measure 6 to 8 by 2 to 4 u and the sporozoites are very small, rounded bodies.) The sporulation time is 2 days.
The oocysts of E. cylindrica intergrade to some extent with those of E. ellipsoidalis in size and shape, but other characters indicate that they are separate species.
Life Cycle: Unknown. Wilson (1931) found oocysts in a calf from the eleventh to twentieth days after experimental infection.
Pathogenesis: This species appears to be somewhat pathogenic. Wilson (1931) observed blood in the feces of an experimentally infected calf 6 days after infection. Rao and Hiregaudar (1954) considered this species pathogenic in zebu calves.