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

Abstract

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.

Prevalence of Cryptosporidium spp. infection in working horses in Egypt

“…Studies from China that used polymerase chain reaction (PCR) to investigate Cryptosporidium spp. prevalence in adult horses reported an average prevalence of 1.8-3.1%(Li, et al 2019, Qi et al 2015, Xu, et al 2022) which is much lower than the prevalence reported here. A recent systematic review and meta-analysis reported a pooled prevalence of 13.8% from studies that used microscopy compared with only 4.7% from studies that used PCR (Hatam-Nahavandi, et al 2019).…”

“…Other limitations of the current study were that samples were collected at a single time point and therefore we did not consider intermittent shedding of Cryptosporidium spp. oocysts (Xu, et al 2022) which might have underestimated the prevalence reported. Furthermore, neither locations nor horses were randomly selected to be included in the current study which might limit the generalisability of our results.…”

“…The prevalence in adult horses appeared to vary according to geographic location of the study and the detection method used. Reported prevalence estimates ranged from 1.8% to up to 39% (Guo et al 2014, Johnson et al 1997, Li et al 2019, Majewska et al 2004, Veronesi, et al 2010, Xu, et al 2022. Factors reported to be associated with shedding Cryptosporidium spp.…”

“…Humans are primarily infected with two genotypes, C. parvum and C. hominis (Ryan et al 2021) which have been also reported in horses suggesting a potential zoonotic transmission of Cryptosporidium spp. between horses and humans (Xu et al 2022). Although molecular studies indicated that humans and horses are infected with differing Cryptosporidium spp.…”

“…This was also consistent with prevalence studies of Cryptosporidium spp. infection which reported lower prevalence when PCR is used as sole detection method (Hatam-Nahavandi, et al 2019,Li, et al 2019, Qi, et al 2015, Xu, et al 2022. Overall, epidemiological studies of Cryptosporidium spp.…”