Eimeria macusanuensis is an important coccidian intestinal parasite of New World camelids. It may be the same parasite as E. camelli, a similar-appearing intestinal coccidian of Old World camels, but this has not been proven. Eimeria macusanuensis affects all ages of camelid, not just juveniles. Its contribution to illness may not be appreciated, since some camelids become sick up to two weeks before patent infections are detected in their herdmates. Gross lesions are often absent, and histological lesions can be so segmental that they are missed on routine necropsy.