جداسازی،شناسایی و تعیین هویت مولکولی گونه های کریپتوسپوریدیوم در اسهال گوساله ها

Background and Aim: Cryptosporidium is a well-known cause of neonatal enteritis in cattle worldwide and Cryptosporidiosis is the zoonotic infection in human and animals. Cattle are commonly infected with four different species of Cryptosporidium but only one of these, Cryptosporidium parvum, is associated with clinical disease.Identification of species in cases of calf scour can give an indication if Cryptosporidium is the causative agent or not. In addition, C. parvum is a zoonotic species and so has implications for human health and for this reason it is important to identify the species of Cryptosporidium infecting cattle. Materials and methods: Studies were conducted in calves aged less than 3 months for a period of 2 years. During the study period, 160 dung samples were collected from neonatal calves and examined first microscopically and then by molecular techniques. Stools were analyzed for the presence of Cryptosporidium oocysts by Sheather's Sugar Flotation Solution followed by Ziel-Neelsen staining method.DNA was extracted and multiplex nested-PCR protocol were done to identify three cattle-adapted species (C. andersoni, C. bovis and C. ryanae) plus the zoonotic species C. parvum in a nested PCR. Results: Cryptosporidium spp. infection was detected in 55 (34.37%) of 160 calves with a history of diarrhea that was positively related to the diarrheic status of the calves (p< 0.05). Detection of a 305 bp fragment of SSU-rRNA gene specific for species Cryptosporidium parvum revealed the presence of this species in all microscopically positive samples. Conclusions: This parasite appears to be an important cause of calf scours and the prevalence of Cryptosporidium oocysts was significantly high in diarrheic animals. There is need for a long term study to elucidate the effect of other risk factors for this infection in calves, and to determine the main cause of the occurrence of diarrhea in relation to cryptosporidiosis and other infections. Overall, the results showed a high number of infected animals suggesting the parasite C. parvum as a major parasitic disease agent of neonatal calves with diarrhea in dairy farms of the Alborz and Shahrood provinces, Iran.Keywords: Cryptosporidium, diarrhea, calves.