Occurrence and molecular identification of Cryptosporidium spp. in dairy calves in Xinjiang, Northwestern China.

A total of 514 fecal samples were collected from dairy calves on 15 farms in the Xinjiang Uyghur Autonomous Region in Northwestern China and were screened for Cryptosporidium spp. by PCR. The overall prevalence of Cryptosporidium was 16.0% (82/514), and the infection rate was 15.6% (37/237) and 16.2% (45/277) in pre- and post-weaned calves, respectively. PCR-restriction fragment length polymorphism (RFLP) and DNA sequence analyses of 82 positive fecal samples revealed the presence of four Cryptosporidium species; of these, 22 were Cryptosporidium parvum, 20 were Corynebacterium bovis, 9 were Cryptosporidium ryanae, 25 were Cryptosporidium andersoni, 2 were mixed C. bovis/C. parvum, and 4 were mixed C. bovis/C. ryanae infections. In pre-weaned calves, C. parvum was the most common species (22/37, 59.5%). In contrast, C. andersoni was the dominant species (23/45, 51.1%) in post-weaned calves. Subtyping analysis based on the 60-kDa glycoprotein (gp60) gene successfully identified 15 C. parvum isolates as being in the IId family; 11 were IIdA15G1 and 4 were IIdA14G1. Recent findings describing the C. parvum IId subtypes as the dominant group in humans and animals in China indicate that dairy calves may be an important source of zoonotic Cryptosporidium in China.