Prevalence and genotypic identification of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in pre-weaned dairy calves in Guangdong, China

Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi are common enteric pathogens in humans and animals. Data on the transmission of these pathogens are scarce from Guangdong, China, which has a subtropical monsoon climate and is the epicenter for many emerging infectious diseases. This study was conducted to better understand the prevalence and identity of the three pathogens in pre-weaned dairy calves in Guangdong. The occurrence and genetic identity of three pathogens were analyzed by polymerase chain reaction. PCR-positive products were sequenced to determine the species and genotypes. A Chi-square test was used to compare the prevalence of pathogens among sampling dates, age groups, or clinical signs. The detection rates of Cryptosporidium spp., G. duodenalis and E. bieneusi were 24.0% (93/388), 74.2% (288/388) and 15.7% (61/388), respectively. Three Cryptosporidium species were detected, including C. bovis (n = 73), C. parvum (n = 12) and C. ryanae (n = 7); one animal had concurrence of C. bovis and C. parvum. C. parvum was the dominant species during the first two weeks of life, whereas C. bovis and C. ryanae were mostly seen at 3-9 weeks of age. Sequence analysis identified the C. parvum as subtype IIdA19G1. Assemblage E (n = 282), assemblage A (n = 1), and concurrence of A and E (n = 5) were identified among G. duodenalis-positive animals using multilocus genotyping (MLG). Altogether, 15, 10 and 17 subtypes of assemblage E were observed at the bg, gdh and tpi loci, respectively, forming 49 assemblage E MLGs. The highest detection rate of G. duodenalis was found in winter. Sequence analysis identified genotypes J (n = 57), D (n = 3) and one concurrence of J and D among E. bieneusi-positive animals. The detection rate of E. bieneusi was significantly higher in spring (38.0%; 41/108) than in summer (7.2%; 8/111) and winter (7.1%; 12/169). These results indicate a common occurrence of C. parvum subtype IIdA19G1, G. duodenalis assemblage E, and E. bieneusi genotype J in pre-weaned dairy calves in Guangdong. More studies are needed to understand the unique genetic characteristics and zoonotic potential of the three enteric pathogens in the province.