Molecular detection and genetic characteristics of Cryptosporidium spp. in Chinese racehorses

Background Cryptosporidium is a protozoan parasite causing diarrhoea in humans and animals. Although Cryptosporidium has been found in domestic horses (farmed or kept at pasture), there has been only one published study of Cryptosporidium infections in Chinese racehorses, which was restricted to a very small geographical area. Objectives To investigate the presence of Cryptosporidium spp. in the faeces of racehorses in China and to perform molecular characterisation of the parasite. Study design Cross-sectional. Methods A total of 621 fresh faecal samples were collected for DNA extraction from racehorses at 17 equestrian clubs from 12 provinces of China from December 2016 to May 2018. All the DNA were analysed for the presence of Cryptosporidium species/genotypes and subtypes by PCR amplification of the small subunit ribosomal RNA and 60 kDa glycoprotein genes respectively. Results PCR analysis revealed that 11 samples (1.8%) were positive for Cryptosporidium spp. Among them seven samples were identified as C. parvum and four were C. hominis. The C. parvum isolates were identified as subtype IIdA14G1 (n = 4) and IIdA15G1 (n = 3), while all C. hominis isolates were identified as subtype IkA18G1 (n = 4). Main limitations A single faecal sample from each horse was used instead of multiple samples that could improve the detection rates of the parasite. Conclusions Although Cryptosporidium infection rate was relatively low in the investigated racehorses, the presence of zoonotic subtypes IIdA14G and 1IIdA15G1 of C. parvum and IkA18G1 of C. hominis, suggesting that these animals are a potential source of Cryptosporidium in humans.