Accessible Unlicensed Requires Authentication Published by De Gruyter October 22, 2016

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

Makoto Matsubayashi, Yuri Sasagawa, Tsunehiko Aita, Masaharu Tokoro, Makoto Haritani and Tomoyuki Shibahara
From the journal Acta Parasitologica


Of the three species of Entamoeba found in swine, namely E. histolytica, E. polecki and E. suis, E. histolytica can also infect humans, producing colitis or abscesses of liver and leading to death. However, the pathogenicity of other species of Entamoeba 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, E. polecki and E. suis trophozoites were mainly detected at lamina propria and surface of the lesion, respectively, and Lawsonia intracellularis, 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 E. polecki and E. suis. These findings corroborate our previous reports that the two Entamoeba spp. are pathogenic in pigs as aggravations of symptoms with L. intracellularis. This is the first report about mixed infection with E. polecki and E. suis.

Conflict of interest

  1. The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.


We thank Mr. M. Kobayashi and Ms. M. Shimada (National Institute of Animal Health, Japan) for assistance with histopathological observations, and we thank Dr. N. Abe (Osaka City Institute of Public Health and Environmental Sciences, Japan) for advice on molecular assays.


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Received: 2015-12-9
Revised: 2016-5-6
Accepted: 2016-5-16
Published Online: 2016-10-22
Published in Print: 2016-12-1

© 2016 W. Stefański Institute of Parasitology, PAS