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A total of 1366 fecal samples from the Ningxia Autonomous Region were examined.The overall infection rates for Cryptosporidium spp.and G.duodenalis were 1.61%and 2.12%,respectively.Cryptosporidium was only detected in preweaned calves and adults older than 2 years,whereas G.duodenalis was only detected in calves aged less than 11 months.Cryptosporidium spp.were characterized with a PCR-restriction fragment length polymorphism analysis and DNA sequence analysis of the small subunit rRNA gene.Three Cryptosporidium species were identified: C.parvum(n =15)and C.bovis(n =4)in preweaned calves,and C.andersoni(n =4)in adults aged over 2 years.A DNA sequence analysis of the gp60 gene suggested that the 15 C.parvum isolates all belonged to subtype ⅡdA 15G 1.Twenty-nine G duodenalis isolates were analyzed by DNA sequencing of the triosephosphate isomerase(tpi)and glutamate dehydrogenase(gdh)genes.Two G duodenalis assemblages were identified,assemblages E(n =15)and B(n =4,one subtype B1 and three subtype B2)in preweaned calves,and assemblage E(n =10)in 3-11-month-old calves.The predominance of C.parvum detected in preweaned calves and the first identified subtype ⅡdA15G1 in dairy cattle,and the dominant G.duodenalis assemblage E in this study differed considerably from those found in Henan,Heilongiiang,and Shannxi Provinces.Our findings further confirm the dominance of C.parvum Ⅱd subtypes in China.