Prevalence and Genetic Identification of Three Entamoeba Species in Pigs in Southeastern China

Parasitic Entamoeba spp. can infect many classes of vertebrates including humans and pigs. Entamoeba suis and zoonotic Entamoeba polecki have been identified in pigs, and swine are implicated as potential reservoirs for Entamoeba histolytica. However, the prevalence of Entamoeba spp. in pigs in southeastern China has not been reported. In this study, 668 fecal samples collected from 6 different regions in Fujian Province, southeastern China, were analyzed to identify three Entamoeba species by nested PCR and sequencing analysis. The overall prevalence of Entamoeba spp. was 55.4% (370/668; 95% CI 51.6% to 59.2%), and the infection rate of E. polecki ST1 was the highest (302/668; 45.2%, 95% CI 41.4% to 49.0%), followed by E. polecki ST3 (228/668; 34.1%, 95% CI 30.5% to 37.7%) and E. suis (87/668; 13.0%, 95% CI 10.5% to 15.6%). E. histolytica was not detected in any samples. Moreover, the coinfection rate of E. polecki ST1 and ST3 was 25.1% (168/668; 95% CI 21.9% to 28.4%), the coinfection rate of E. polecki ST1 and E. suis was 3.7% (25/668; 95% CI 2.3% to 5.2%), the coinfection rate of E. polecki ST3 and E. suis was 0.3% (2/668), and the coinfection rate of E. polecki ST1, E. polecki ST3, and E. suis was 4.0% (27/668; 95% CI 2.5% to 5.5%). A representative sequence (MK347346) was identical to the sequence of E. suis (DQ286372). Two subtype-specific sequences (MK357717 and MK347347) were almost identical to the sequences of E. polecki ST1 (FR686383) and ST3 (AJ566411), respectively. This is the first study to survey the occurrence and to conduct molecular identification of three Entamoeba species in southeastern China. This is the first report regarding mixed infections with E. suis, E. polecki ST1, and E. polecki ST3 in China. More research studies are needed to better understand the transmission and zoonotic potential of Entamoeba spp.