Occurrence and genetic identifications of porcine Entamoeba, E. suis and E. polecki, at Tangerang in West Java, Indonesia

Entamoeba suis and E. polecki subtype (ST) 1 and ST3 recently have been inferred to be virulent in pigs. However, because relevant molecular epidemiological surveys have been limited, the prevalences of these species remain unknown and their pathogenicities are still controversial. We surveyed 196 fecal samples of pigs (118 of adults, 78 of piglets) at Tangerang in West Java, Indonesia, in 2017, employing PCR using porcine Entamoeba-specific primers. E. suis was the more frequently detected species, observed in 81.1% of samples, while E. polecki ST1 and ST3 were detected in 18.4% and 17.3% of samples, respectively; mixed infections (harboring 2-3 species or subtypes of Entamoeba) were confirmed in 29.3% of positive samples. Statistically significant differences in the positive rates were not seen between adult pigs and piglets, except for those of E. polecki ST3. The prevalences of Eimeria spp. and/or Cystoisospora suis (79.1%), strongyles (55.6%), and Strongyloides spp. (6.1%) were also observed morphologically in the samples. Further chronological or seasonal investigations of pigs and humans in these high-prevalence areas are needed to assess the virulence of the Entamoeba parasites, including the effects on pig productivity, and to evaluate the zoonotic impacts of these organisms.

Development of molecular diagnostic protocols for detecting three types of Entamoeba from diarrheal and asymptomatic pigs and environmental moist soils

Entamoeba suis and Entamoeba polecki subtypes (ST) 1 and 3 have recently been implicated in disease outbreaks in pigs. However, the distributions of these parasites in Japan and the potential sources of infection on farms still remain unclear. Here, we examined a farm of fattening/growing pigs with abnormal feces in Kagoshima Prefecture, Japan, and found the presence of parasites in the farm environment. Examination of intestinal tissues from pigs presenting with ulcerative colitis revealed a large number of trophozoites that had invaded the lesions. We identified single and mixed infections of E. suis and E. polecki ST1 and ST3 in paraffin sections or fecal samples from affected pigs. Two subtypes of Entamoeba were identified using four primer sets by PCR and sequencing. The parasites were detected in moist soil samples obtained around the drinking water source or puddles, implicating transmission of cysts via contaminated soils. Additionally, we found evidence of Entamoeba spp. and coinfections in surveyed pigs without any diarrhea at two neighboring farms. Our results establish methods for successfully identification of parasites, including cases in which multiple infections are present.