Genetic Characterization and Zoonotic Analyses of <i>Enterocytozoon bieneusi</i> from Cats and Dogs in Shanghai in China

<b><i>Background:</i></b> <i>Enterocytozoon bieneusi</i> is reported to be a common microsporidian of humans and animals in various countries. However, limited information on <i>E. bieneusi</i> has been recorded in cats (<i>Felis catus</i>) and dogs (<i>Canis familiaris</i>) in China. Here, we undertook molecular epidemiological investigation of <i>E. bieneusi</i> in cats and dogs in Shanghai, China. <b><i>Methods:</i></b> A total of 359 genomic DNAs were extracted from individual fecal samples from cats (<i>n</i> = 59) and dogs (<i>n</i> = 300), and then were tested using a nested PCR-based sequencing approach employing internal transcribed spacer (ITS) of nuclear ribosomal DNA as the genetic marker. <b><i>Results:</i></b> <i>Enterocytozoon bieneusi</i> was detected in 34 of 359 (9.5%) (95% confidence interval [6.7 - 13.0%]) fecal samples from cats (32.2%; 19/59) and dogs (5.0%; 15/300), including 24 stray cats and dogs (22.6%; 24/106), as well as 10 household/raised cats and dogs (4.0%; 10/253). Correlation analyses revealed that <i>E. bieneusi</i> positive rates were significantly associated with stray cats and dogs (<i>p</i> < 0.05). The analysis of ITS sequence data revealed the presence of five known genotypes, CD7, CHN-HD2, D, PtEb IX, and Type IV, and two novel genotypes, D-like1 and PtEb IX-like1. Zoonotic genotype D was the predominant type with percentage of 61.8% (21/34). Phylogenetic analysis of ITS sequence data sets showed that genotypes D, D-like1, and Type IV were clustered within Group 1, showing zoonotic potential. The others were assigned into Group 10 with host specificity. <b><i>Conclusions:</i></b> These findings suggested that cats and dogs in Shanghai harbor zoonotic genotype D of <i>E. bieneusi</i> and may have a significant risk for zoonotic transmission. Further insight into the epidemiology of <i>E. bieneusi</i> in other animals, water, and the environment from other areas in China will be important to have an informed position on the public health significance of microsporidiosis caused by this microbe.