Prevalence of Enterocytozoon bieneusi and Blastocystis sp. infection in foxes (Alopex lagopus) in northern China.

To examine the prevalence of E. bieneusi and Blastocystis sp. in foxes in China, this study analyzed the prevalence and distribution of genotypes or subtypes. A total of 352 fresh fecal samples were collected from foxes across five provinces in northern China and analyzed using PCR. The overall prevalences of E. bieneusi and Blastocystis sp. were 48.3% and 2.0%, respectively; the highest prevalences were found in Shandong Province, with 87.1% and 5.4%, respectively. The prevalence rates were influenced by several factors; a breeding scale value <1,500 was related to higher prevalences. Multivariate analysis showed that the region and breeding scale were the main risk factors for E. bieneusi. Eleven genotypes of E. bieneusi were identified, all of which are classified within Group 1. This includes five previously characterized genotypes and six novel genotypes. Among these, CHN-F1 was the predominant genotype, accounting for 67.7% of cases. Blastocystis sp. was detected with only one subtype (ST3), which represents the first report of this genotype in foxes. The identification of E. bieneusi in foxes and the first detection of the ST3 subtypes of Blastocystis sp. contribute to a more comprehensive understanding of the epidemiology of these microeukaryotes. These findings suggest a potential pathway for the transmission of microeukaryotes from fox farms to human populations, underscoring the importance of monitoring the public health risks.