Molecular characterization of human pathogenic Enterocytozoon bieneusi, Giardia duodenalis and Cyclospora cayetanensis of diarrheal outpatients in Yangtze river delta region, China

Giardia duodenalis, Enterocytozoon bieneusi and Cyclospora cayetanensis are usually classified as Neglected Tropical Diseases, causing giardiasis, microsporidiosis and cyclosporiasis, respectively, which significantly contributed to food- and water-transmitted intestinal illnesses in both humans and animals. In this study, we conducted on the prevalence and molecular characterization of Giardia, E. bieneusi and C. cayetanensis of diarrheal outpatients from three areas in the Yangtze River Delta, China. A total of 2 720 fecal samples were collected and nested PCR was used to identify and describe the genetic characteristic of Giardia, E. bieneusi and C. cayetanensis. The overall prevalence of the three pathogens was 2.54% (69/2 720), with 1.03% for E. bieneusi (28/2 720), 0.8% for G. duodenalis (22/2 720), and 0.7% for C. cayetanensis (19/2 720), respectively. 9 E. bieneusi genotypes, together with two known genotypes A (n = 20) and D (n = 1), and 7 novel genotypes named JDFY-1 to JDFY-7 were identified. All the genotypes were clustered into zoonotic potential Group 1. In addition, 22 G. intestinalis-positive samples were genotyped as assemblages A (n = 4), B (n = 17) and E (n = 1). 19 stool samples were identified to be C. cayetanensis and two new sequences were found. Therefore, our results underscored the existence and importance of E. bieneusi, Giardia and C. cayetanensis in diarrheal outpatients. Furthermore, the findings of E. bieneusi genotypes and new sequences of Giardia and C. cayetanensis indicates a high zoonotic potential of these pathogens in diarrheal outpatients. A broader range of investigations should be conducted on human, animal, and environmental sources to better understand the real transmission routes of the three enteric zoonotic protozoan.