Experimental histopathological study of chicks infected with Cryptosporidium baileyi isolated from wild pigeons in Mosul

The aim of this study was to investigate naturally occurring cryptosporidiosis in pigeons in Mosul city as well as the pathology of experimental C. baileyi infection in chicks. Prevalence of the naturally occurring cryptosporidiosis in the pigeons was 30% according to morphological features of the isolated oocysts and distribution of the lesions of the experimental infection in chicks, the cryptosporidium was diagnosed as C. baileyi. Using a dose of 1000 oocysts, the infection was induced in chikens. Oocysts shedding was noted in the infected chickens at the 7th post – infection (p.i.) day and increased till the 15th p.i. day. Infected chicks showed dullness and anorexia. Microscopically p.i. day 7, there were necrosis of the tips of some of the intestinal villi, mucinous degeneration of the intestinal mucosa, and the presence of large numbers of the parasite in the tips of the intestinal villi. On p.i. day 10, necrosis of the tips of the villi was more extensive and the necrotic cells were sloughed into the lumen and accumulated as debris. Inflammatory mononuclear cells were seen infiltrating the various layers of the intestine. Similar but more extensive lesions were seen on p.i. day 15.