Spontaneous cryptosporidiosis in an adult female rabbit.

An asymptomatic adult female rabbit had intestinal cryptosporidiosis. The ileum had blunted villi, a decrease in villus-crypt ratio and a mild edema in the lamina propria. Transmission electron microscopy showed the parasite to be a Cryptosporidium similar to those reported in mouse, guinea pig, lamb, calf, horse, monkey and man. This organism is referred to as Cryptosporidium cuniculus. Scanning electron microscopy on ileal mucosa showed altered intestinal microvilli in the attachment of the cryptosporidia. It is postulated that the organism was enveloped by the microvilli of the ileal epithelial cells which then fused and formed a continuous double membrane around the parasite.