Host-adaptation of the rare Enterocytozoon bieneusi genotype CHN4 in Myocastor coypus (Rodentia: Echimyidae) in China.

Background: Enterocytozoon bieneusi is a zoonotic gastrointestinal pathogen and can infect both humans and animals. The coypu (Myocastor coypus) is a semi-aquatic rodent, in which few E. bieneusi infections have been reported and the distribution of genotypes and zoonotic potential remains unknown.
Methods: A total of 308 fresh fecal samples were collected from seven coypu farms in China to determine the infection rate and the distribution of genotypes of E. bieneusi from coypus using nested-PCR amplification of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene.
Results: Enterocytozoon bieneusi was detected with an infection rate of 41.2% (n = 127). Four genotypes were identified, including three known genotypes (CHN4 (n = 111), EbpC (n = 8) and EbpA (n = 7)) and a novel genotype named CNCP1 (n = 1).
Conclusions: The rare genotype CHN4 was the most common genotype in the present study, and the transmission dynamics of E. bieneusi in coypus were different from other rodents. To the best of our knowledge, this is the first report of E. bieneusi infections in coypus in China. Our study reveals that E. bieneusi in coypus may be a potential infection source to humans.