Host specificity studies and oocyst description of a Cryptosporidium sp. isolated from ostriches.

Oocysts of a Cryptosporidium sp. were found in the feces of 14 of 165 (8.5%) ostriches imported into Canada. The genus identity of the oocysts was confirmed by morphology. The mean (+/- SD) size of 40 oocysts was 4.6 (0.53) x 4.0 (0.42) microns (range 3.9-6.1 x 3.3-5.0 microns) with a shape index (length/width ratio) of 1.15 (range 1.00-1.38). In cross-transmission experiments, this Cryptosporidium sp. failed to infect suckling mice, chickens, turkeys, or quail (Coturnix coturnix japonica). A comparison of oocyst structure and host susceptibility indicates that the Cryptosporidium sp. from ostriches is different from C. meleagridis, C. baileyi, and Cryptosporidium sp. of bobwhite quail.