Moore, Brown and Carter (1954) were unable to infect the chicken, guinea fowl, ringnecked pheasant or bobwhite quail with this species.
Location: Duodenum, jejunum and upper ileum as far as 2 inches anterior to the yolk stalk rudiment.
Geographic Distribution: North America.
Prevalence: Apparently uncommon.
Morphology: This species closely resembles E. innocua, according to Moore, Brown and Carter (1954). The oocysts are subspherical, smooth, 16 to 26 by 14 to 24 u with a mean of 22 by 20 u, without a micropyle or polar granule. No other morphological information was given. The sporulation time is 48 hours.
Life Cycle: Unknown. According to Moore, Brown and Carter (1954), the endogenous stages occur in the epithelial cells of the tips of the villi, extend along the sides of the villi to some extent, but never invade the crypts and deep glands. Oocysts first appear in the feces 96 hours after infection, and the patent period is 12 to 13 days.
Pathogenesis: This species is apparently non-pathogenic. Moore, Brown and Carter (1954) observed no signs of infection, diarrhea or gross lesions in poults less than 5 weeks old which had been infected with massive doses of sporulated oocysts.
Immunity: Moore, Brown and Carter (1954) immunized turkey poults by feeding them 10,000 to 15,000 sporulated oocysts every 4 days until they ceased to shed oocysts; this occurred in less than a month. Poults which had been immunized against E. subrotunda were not immune to E. innocua and E. dispersa, and poults which had been immunized against the latter two species were not immune to E. subrotunda. This was the primary basis for separating E. subrotunda from E. innocua.