United States Department of Agriculture, Environmental Microbial and Food Safety Laboratory, Animal and Natural Resources Institute Agricultural Research Service, Building 173, BARC-East, 10300 Baltimore Avenue, Beltsville, MD 20705, USA.
Parasitol Res. 2012 May;110(5):2033-41. doi: 10.1007/s00436-011-2732-6. Epub 2011 Dec 7.
To determine the prevalence and genotype distribution of Enterocytozoon bieneusi in weaned beef calves in the USA, fecal samples were collected from 819 calves (6-18 months of age) from 49 operations. Feces were sieved and subjected to density gradient centrifugation to remove fecal debris and to concentrate spores. DNA extracted from each sample was subjected to the polymerase chain reaction (PCR) to amplify the complete internal transcriber spacer (ITS). All PCR-positive specimens were sequenced to determine the genotype(s) present. Overall, E. bieneusi was detected in 34.8% of the 819 fecal samples. The highest prevalence was found in the Midwest region (42.7%) followed by the South (35.8%) and the West (23.2%). The prevalence of E. bieneusi varied considerably from operation to operation (0-100%). A prevalence of 100% was observed in three operations, one in the Midwest and two in the South; E. bieneusi was not found in six operations, three in the South and three in the West. Sequence analysis revealed the presence of six genotypes, four previously reported (I, J, BEB4, and type IV) and two novel genotypes (BEB8 and BEB9). Mixed infections were identified in five specimens, three contained I and BEB4 and two contained J and BEB4. Most of the positive calves (238 of 285) harbored genotypes with zoonotic potential including I (59), J (108), BEB4 (65), type IV (1), mixed I/BEB4 (3), and mixed J/BEB4 (2).
为了确定美国断奶肉牛犊中肠微孢子虫的流行情况和基因型分布，从 49 个养殖场的 819 头（6-18 月龄）犊牛中采集了粪便样本。粪便经筛检后，通过密度梯度离心法去除粪便残渣并浓缩孢子。从每个样本中提取的 DNA 经聚合酶链反应（PCR）扩增完整的内部转录间隔区（ITS）。所有 PCR 阳性标本均进行测序以确定存在的基因型。总体而言，819 份粪便样本中有 34.8%检测到肠微孢子虫。中西部地区（42.7%）的检出率最高，其次是南部（35.8%）和西部（23.2%）。从养殖场到养殖场，肠微孢子虫的检出率差异很大（0-100%）。三个养殖场的检出率为 100%，其中一个在中西部，两个在南部；六个养殖场未检出肠微孢子虫，其中三个在南部，三个在西部。序列分析显示存在六种基因型，其中四种为先前报道的（I、J、BEB4 和 IV 型），两种为新型基因型（BEB8 和 BEB9）。五个标本中发现了混合感染，其中三个含有 I 和 BEB4，两个含有 J 和 BEB4。大多数阳性犊牛（285 头中的 238 头）携带具有人畜共患潜力的基因型，包括 I（59 头）、J（108 头）、BEB4（65 头）、IV 型（1 头）、I/BEB4 混合感染（3 头）和 J/BEB4 混合感染（2 头）。
