Prevalence and Genetic Identification of Three <i>Entamoeba</i> Species in Pigs in Southeastern China

Abstract

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