Prevalence and Multi-Locus Genotyping of Enterocytozoon bieneusi in Dogs from Fujian Province, Southeast China

Enterocytozoon bieneusi is a microsporidian species found ubiquitously in both invertebrate and vertebrate hosts including domestic and wild animals and humans. Enterocytozoon bieneusi typically causes severe or chronic diarrhea, malabsorption and emaciation. This study aimed to investigate the prevalence and genotypic distribution of E. bieneusi in dogs in Fujian province, China. A total of 506 fecal samples from dogs were randomly collected from eight districts in Fujian province, China. The presence of E. bieneusi was confirmed through nested PCR targeting ITS gene. Further multilocus sequence typing (MLST) focused on the three microsatellite loci (MS1, MS3, and MS7) and minisatellite locus (MS4) loci. As a result, the infection rates of E. bieneusi in dogs were found to be 5.93% (30/506). A highly significant difference in the prevalence of E. bieneusi was observed across different urban areas (p < 0.01), with Longyan city exhibiting the highest infection rate (24.62%, 16/65), Zhangzhou and Xiamen the lowest (0.00%). Prevalence also varied significantly by source (p < 0.01), age (p < 0.01), gender (p < 0.05), symptom status (p < 0.01), and season (p < 0.01). Three known genotypes of E. bieneusi were identified in 30 dogs' positive samples, including EbpC, PigEBITS5 and PtEb IX, whereas FJLYD1, FJLYD2 and FJSMD have been identified as new genotypes. EbpC, PigEBITS5, FJLYD1, FJLYD2, and FJSMD all belong to Group 1, while PtEb IX is assigned to Group 11. Genotypes belonging to Group 1, the first major phylogenetic clade, are considered to possess potential zoonotic risks. None of the positive samples amplified at all four loci, forming a single multilocus genotype (MLG). This study contributes to a deeper understanding of E. bieneusi in dogs, which provides critical data for the development of targeted control strategies in Fujian province.