Hosts: Cottontail (Sylvilagus floridanus), domestic rabbit (experimentally).
Location: Posterior part of small intestine, large intestine.
Geographic Distribution: North America.
Prevalence: Common in cottontails. Ecke and Yeatter (1956) found this species in 31% of 32 cottontails in Illinois.
Morphology: The oocysts are subcylindrical or elongate ellipsoidal to ovoid, smooth, pinkish yellow, 33 to 44 by 16 to 23 u with a mean of 39 by 20 u. A micropyle is present. An oocyst polar granule is absent. An oocyst residuum is usually absent. A sporocyst residuum is present. The sporozoites are elongate ovoid, with a Stieda body. The sporulation time is 2 to 3 days.
Life Cycle: The endogenous cycle of this species has not been described.
Pathogenesis: This species is slightly to markedly pathogenic, depending upon the extent of the infection. The affected intestinal mucosa is inflamed and hyperemic, and caseous necrosis may be present.
Remarks: Pellerdy (1954a) found a coccidium which he believed to be E. neoleporis in domestic rabbits in Hungary and described its pathogenic effects. He believed that E. coecicola was a synonym of this species and he may be right. Carvalho (1942) transmitted E. neoleporis from the cottontail to the domestic rabbit. However, for the present I am using the name E. neoleporis for the cottontail form alone.