Synonyms: Coccidium perforans, Eimeria exigua, E. lugdunumensis.
Hosts: Domestic rabbit, varying hare (Lepus americanus), east Greenland hare (L. arcticus groenlandicus), California jack rabbit (L. californicus), European hare (L. europaeus), Brazilian cottontail (Sylvilagus brasiliensis), cottontail (Sylvilagus floridanus) (experimentally).
Location: Thruout small intestine and also in cecum.
Geographic Distribution: Worldwide.
Prevalence: Common. Kessel and Jankiewicz (1931) found it in 30% of over 2000 rabbits in California.
Morphology: The oocysts are ellipsoidal, sometimes ovoid, smooth, colorless to pinkish, 24 to 30 by 14 to 20 u with a mean of 26 by 16 u. A micropyle is absent. An oocyst polar granule is absent. An oocyst residuum is present. The sporocysts are ovoid, with a Stieda body. A sporocyst residuum is present. The sporulation time is 2 days.
Life Cycle: Rutherford (1943) described the life cycle of this species. The endogenous stages are found above the nuclei of the epithelial cells of the intestine. There are 2 asexual generations of merozoites, followed by microgamete and macrogamete production. Completion of the endogenous cycle takes 5 days, and the prepatent period is 5 to 6 days.
Pathogenesis: E. perforans is one of the less pathogenic intestinal coccidia of rabbits, but it may nevertheless cause mild to moderate signs if the infection is heavy enough. The duodenum may be enlarged and edematous, sometimes chalky white; the jejunum and ileum may contain white spots and streaks, and there may be petechiae in the cecum.