Epidemiological Survey Of Cryptosporidium Parvum In Neonatal Calves In Parts Of Xinjiang

Cryptosporidium parvum is an important zoonotic opportunistic protozoan parasite,which is one of the four main pathogens causing diarrhea in calves and is widely prevalent in the world.Cattle are considered to be the main reservoir for zoonotic Cryptosporidium parvum infections,and are associated with the water-borne outbreaks of human cryptosporidiosis,with a large zoonotic risk.With the development of the intensive cultivation of the cattle industry in our country,the prevention and control of the calf diarrhea has become an important problem to be solved.The epidemiological investigation of Cryptosporidium parvum in newborn calves in some areas of Xinjiang was carried out based on the actual production of dairy cattle industry.This paper can provide the basic data for the epidemiological study and prevention and treatment of Cryptosporidium parvum in Xinjiang dairy cattle.(1)From September 2017 to July 2018,saturated sucrose floating method,modified acid-fast staining and nested PCR amplification PCR-RFLP analysis and sequence analysis of Cryptosporidium SSU rRNA gene were used to investigate the infection of Cryptosporidium parvum the feces of 232 newborn calves in 1 month old from 12 intensive dairy farms in 7 areas of Wushi,Alar,Wensu,Shihezi,Hutubi,Tiemenguan and Kuitun in Xinjiang.The microscopical examination showed that Cryptosporidium is 4~6 ?m in diameter.The Cryptosporidium has bluepurple refraction,which is sphericalor elliptical,with 1 large remnant and 4 sporozoites.The oocyst of Cryptosporidium was rosy-red and its surrounding background was light blue after modified acid-fast staining.The DNA of fecal samples of 232 newborn calves in 12 dairy farms were amplified by nested PCR based on SSU rRNA gene.The overall prevalence of Cryptosporidium was 38.4%,the infection rate of Cryptosporidium parvum was 37.9%.The results showed that the infection rate of Cryptosporidium was significantly different between diarrhea and non-diarrhea calves(P<0.001).Based on RFLP analysis and sequence analysis of SSU rRNA gene,three species of Cryptosporidium were identified: Cryptosporidium parvum,Cryptosporidium bovis and Cryptosporidium ryanae,where Cryptosporidium parvum is the dominant species of the infected species,and which is common in the newborn calves of the study areas and has a large zoonotic risk.(2)From September 2017 to September 2018,A 1 year follow-up survey was conducted on two largescale cattle farms in Aksu region,southern Xinjiang.Homogeneity of variance analysis showed that there was no significant seasonal difference in the infection rate of Cryptosporidium parvum(P>0.05).There was no seasonal difference in the infection rate of Cryptosporidium parvum in Shituan cattle farms(P>0.05).There were differences in the infection rate of Cryptosporidium parvum in Wutuan cattle farms in summer and winter(P=0.044).