Abstract: A survey of Cryptosporidium was performed in 404 samples from ostriches in ZhengZhou, with the Sheather's sugar flotation technique.The cryptosporidia infection percentage in ostriches was 2.48%(10/404), the oocyst is of 5.43μm×4.38μm with shape index of 1.24(n=50). The pathogenicity of the Cryptosporidium strain to ostriches,chickens and mice were studied. Main clinical signs of cough, asthma, sneezing, cachexia, dyspnea could be observed in the chickens and ostriches that infected with the oocysts ,and the signs in ostriches was mild,but there was no symptom as that of described as above in mice and no oocysts were found in their feces. The regulation of shedding oocysts in chicken was different with it in ostrich ,there were multiple peaks in ostrich.The experiments were carried out on pathology of some organs in young ostriches that infected with Cryptosporidium from ostriches. We found that Cryptosporidium derived from ostrich mainly parasitized in cloaca and bursa of Fabricious of ostriches, mainly caused mucous membrane tumefaction and epithelium cell swell,.The oocyst is identified as Cryptosporidium baileyi according to its’ morphological characteristics, the result of pathogenicity to ostriches, chickens and mice.

Key words: Ostrich , Cryptosporidium , Epidemiology, electron microscope , Characteristic