Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in dairy cattle in Beijing, China.

822 fecal samples from cattle in six areas of Beijing were examined with microscopy for Cryptosporidium oocysts and Giardia cysts. The overall infection rates for Cryptosporidium spp. and Giardia duodenalis were 2.55% and 1.09%, respectively. Cryptosporidium was only detected in calves and heifers, whereas G. duodenalis was found in all age groups. Cryptosporidium spp. were characterized with a PCR-restriction fragment length polymorphism analysis and DNA sequence analysis of the small subunit (SSU) rRNA gene. Two Cryptosporidium species were identified: Cryptosporidium parvum (n=12) and Cryptosporidium andersoni (n=9). Six C. parvum isolates were successfully subtyped with the gp60 gene and three subtypes were detected: IIdA19G1 (n=1), IIdA17G1 (n=1), and IIdA15G1 (n=4). Subtype IIdA17G1 is reported for the first time in cattle worldwide. Nine G. duodenalis isolates were analyzed by sequencing the triosephosphate isomerase (tpi) gene, and only G. duodenalis assemblage E was identified. Therefore, the predominance of C. parvum detected in calves was identical to that found in the Xinjiang Uyghur and Ningxia Hui Autonomous Regions, but differed considerably from that in Henan, Heilongjiang, and Shannxi Provinces. In contrast, the predominance of G. duodenalis assemblage E was more or less similar to its predominance in other areas of China or countries. Our findings confirm the unique character of the C. parvum IId subtypes in China. More systematic studies are required to better understand the transmission of Cryptosporidium and G. duodenalis in cattle in China.