First report of Cryptosporidium viatorum and Cryptosporidium occultus in humans in China, and of the unique novel C. viatorum subtype XVaA3h

BACKGROUND: Cryptosporidium is a genus of common intestinal protozoa, members of which cause diarrhea in a wide variety of hosts. Previous studies on Cryptosporidium in China have mainly focused on diarrhea sufferers, children, and immunodeficient individuals such as HIV/AIDS patients. However, the epidemiological characteristics of Cryptosporidium in the population in rural areas remain unclear. Herein, we investigated the prevalence of, and risk factors for, Cryptosporidium in rural areas of Binyang County, Guangxi Zhuang Autonomous Region, China, and genetically characterized the Cryptosporidium isolates we obtained. METHODS: From August to December 2016, two villages in Binyang County, Guangxi, were sampled using a random cluster sampling method. Fresh fecal samples were collected from all eligible residents (residence time > 6 months). Molecular characterization of Cryptosporidium was carried out based on its SSU rRNA, gp60, actin and hsp70 gene sequences. Fisher’s exact test were conducted to assess the risk factors for Cryptosporidium infection. RESULTS: A total of 400 fecal samples were collected from 195 males (48.8%) and 205 females (51.2%). Two samples (0.5%) were positive for Cryptosporidium and were identified as C. viatorum and C. occultus respectively. Moreover, a new C. viatorum subtype XVaA3h was identified based on the sequence of the gp 60 gene. CONCLUSIONS: To our knowledge, this is the first report of C. viatorum and C. occultus infections in humans in China and of C. viatorum subtype XVaA3h. The findings provide important information on the prevalence of Cryptosporidium in the Chinese population, and expand the range of Cryptosporidium species known to infect people in China.