College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, People's Republic of China.
J Clin Microbiol. 2011 Mar;49(3):1077-82. doi: 10.1128/JCM.02194-10. Epub 2010 Dec 22.
To estimate the prevalence and public health significance of cryptosporidiosis in preweaned calves in China, 801 fecal samples from eight farms in seven areas in Henan Province were examined for Cryptosporidium oocysts. The overall infection rate of Cryptosporidium was 21.5%, with the farm in Xinxiang having the highest prevalence (40%). No significant difference in infection rates was observed between seasons. Cryptosporidium spp. were characterized by PCR-restriction fragment length polymorphism (RFLP) analysis of the small subunit (SSU) rRNA gene and DNA sequencing of the 60-kDa glycoprotein (gp60) gene. The SSU rRNA-based PCR identified four Cryptosporidium species, including Cryptosporidium parvum (54/172), C. bovis (65/172), C. ryanae (19/172), and C. andersoni (12/172), and the occurrence of infections with mixed species (22/172). The earliest detection of C. bovis was in calves of 1 week of age, showing that the prepatent period was shorter than the previously stated 10 to 12 days. Infections with C. parvum peaked in summer, whereas C. bovis dominated in autumn and winter. There was no apparent difference in the age of cattle infected with either C. parvum or C. bovis. Sequencing analysis of the gp60 gene showed all 67 C. parvum samples belonged to subtype IIdA19G1. These findings suggested that the transmission of Cryptosporidium spp. in preweaned calves in Henan, China, appeared to be different from other areas both at genotype and subtype levels. Further molecular epidemiologic studies (including samples from both calves and humans) are needed to elucidate the transmission dynamics and public significance of C. parvum in cattle in China.
为了估计中国未断奶犊牛中隐孢子虫病的流行情况和公共卫生意义，对河南省七个地区的八个农场的 801 份粪便样本进行了隐孢子虫卵囊检查。隐孢子虫的总感染率为 21.5%，其中新乡的感染率最高（40%）。各季节之间的感染率无显著差异。通过聚合酶链反应-限制性片段长度多态性（PCR-RFLP）分析小亚基（SSU）rRNA 基因和 60-kDa 糖蛋白（gp60）基因的 DNA 测序对隐孢子虫进行了特征描述。基于 SSU rRNA 的 PCR 鉴定出四种隐孢子虫，包括微小隐孢子虫（54/172）、牛隐孢子虫（65/172）、瑞安隐孢子虫（19/172）和犬隐孢子虫（12/172），以及混合感染（22/172）。最早检测到的牛隐孢子虫出现在 1 周龄的犊牛中，表明潜伏期比之前报道的 10-12 天更短。微小隐孢子虫感染在夏季达到高峰，而牛隐孢子虫在秋季和冬季占主导地位。感染微小隐孢子虫或牛隐孢子虫的牛的年龄没有明显差异。gp60 基因测序分析显示，所有 67 株微小隐孢子虫均属于亚 IIdA19G1 型。这些发现表明，中国河南未断奶犊牛中隐孢子虫的传播在基因型和亚型水平上似乎与其他地区不同。需要进一步的分子流行病学研究（包括犊牛和人类的样本）来阐明中国牛中微小隐孢子虫的传播动态和公共卫生意义。
