First report of mixed Entamoeba polecki (ST 1) and E. suis infection in piglets shedding abnormalfeces by histopathological and molecular surveys

Of the three species of found in swine, namely , and , can also infect humans, producing colitis or abscesses of liver and leading to death. However, the pathogenicity of other species of has not been fully characterized. Here, we conducted histopathology and molecular surveys on a pig farm where piglets had blackish feces or muddy diarrhea. Histopathological examination of two piglets showed necrosis of the mucous surface at the ileum, cecum, or colon, infiltration of neutrophils, and formation of ulcers. Based on morphological characteristics, and trophozoites were mainly detected at lamina propria and surface of the lesion, respectively, and , a bacterial pathogen, was also detected. Molecular analysis using the small subunit ribosomal RNA gene on other piglets and a sow revealed infection with both and . These findings corroborate our previous reports that the two spp. are pathogenic in pigs as aggravations of symptoms with . This is the first report about mixed infection with and