The infection rate of E. bieneusi in rodent species varies from 2.5–100% worldwide [12, 13]. To the best of our knowledge, this is the first report of E. bieneusi infections in coypus in China. In the present study, the infection rate of E. bieneusi was 41.2% in coypu, which is higher than the infection rate of E. bieneusi reported in brown rats (7.9%) , bamboo rats (5.1%) , experimental rats (4.8%) , commensal rodents (4.0%)  and pet chinchillas (3.6%) in China . In addition, lower infection rates were also reported in wild house mice (10.7%) from a hybrid zone across the Czech Republic-Germany border , and beavers (15.3%) and muskrats (8.4%) from USA . However, higher infection rates of E. bieneusi were reported in chipmunks (71.4%) and woodchucks (100%) from USA . Similar infection rates of E. bieneusi have been reported in small rodents (38.9%) from southwestern Poland , and a laboratory prairie dog colony (37.9%) from USA . The infection rates of E. bieneusi in rodents could be influenced by many factors, such as animal immune status, age distribution, sample size, detection method, feeding environment, management system and population density . Although the high infection rate was detected in coypus in our study, we cannot come to an inference that coypus are more susceptible to E. bieneusi than many other rodent species due to the lack of more investigations.
In the present study, the dominant genotype of E. bieneusi was CHN4, which was detected in six cities except Yongzhou, indicating that genotype CHN4 is commonly found in coypus in China. Interestingly, genotype CHN4 has not been reported in rodents previously. However, it was firstly identified in three human and two cattle samples  and four pre-weaned calf samples (1.9%)  from China. Genotype D was identified in squirrels from China  and USA , chipmunks , bamboo rats  and brown rats [10, 25] from China, house mice from Czech Republic-Germany border  and striped field mice from Poland , and genotype WL4 was observed in squirrels, chipmunks and muskrats from USA [12, 18] (Table 3). EbpA, EbpC, PigEBITS7, S7, Peru16 and CHG4 have also been reported as the most common genotypes [9, 13, 15, 18, 25, 26]. The rare genotype CHN4 was the dominant genotype, indicating that the transmission dynamic of E. bieneusi in coypus is different from other rodents. This may be explained by the unique life habits of coypus as aquatic rodents compared to other rodents involved in previous studies.
Genotypes EbpA and EbpC have been detected in several rodent species (squirrel, house mouse, experimental rat, muskrat, bamboo rat and beaver) worldwide [14, 15, 17, 18, 23] (Table 3). EbpA and EbpC are two of the most common genotypes detected in both immunocompetent and immunocompromised people worldwide . Meanwhile, genotypes EbpA and EbpC have a vast host range, such as non-human primates (NHPs), livestock (cattle, buffalo, sheep and goat), pets (dog and horse), wild animals (deer, fox, raccoon, bear, panda and otter) and birds (pigeon, crane and parrot) . These two genotypes also have been observed in lake water , river water  and wastewater treatment plants [29, 30]. According to these data, the interspecies transmission of genotypes EbpA and EbpC pose a zoonotic risk to human or other animals, and coypus may serve as a reservoir of EbpA and EbpC in the E. bieneusi transmission.
In the phylogenetic analysis, an NJ tree was constructed and the novel genotype CNCP1 clustered with CHN4, EbpC and EbpA in group 1. The majority of the zoonotic genotypes belongs to the group 1, and genotypes CHN4, EbpC and EbpA have been reported in humans [21, 31, 32], indicating that genotype CNCP1 maybe have zoonotic potential and the E. bieneusi isolates in coypus detected in this study can be transmissible from coypus to humans, especially the animal handlers, or vice versa.