Identification of Entamoeba polecki with Unique 18S rRNA Gene Sequences from Celebes Crested Macaques and Pigs in Tangkoko Nature Reserve, North Sulawesi, Indonesia

Unique species of macaques are distributed across Sulawesi Island, Indonesia, and the details of Entamoeba infections in these macaques are unknown. A total of 77 stool samples from Celebes crested macaques (Macaca nigra) and 14 stool samples from pigs were collected in Tangkoko Nature Reserve, North Sulawesi, and the prevalence of Entamoeba infection was examined by PCR. Entamoeba polecki was detected in 97% of the macaques and all of the pigs, but no other Entamoeba species were found. The nucleotide sequence of the 18S rRNA gene in E. polecki from M. nigra was unique and showed highest similarity with E. polecki subtype (ST) 4. This is the first case of identification of E. polecki ST4 from wild nonhuman primates. The sequence of the 18S rRNA gene in E. polecki from pigs was also unique and showed highest similarity with E. polecki ST1. These results suggest that the diversity of the 18S rRNA gene in E. polecki is associated with differences in host species and geographic localization, and that there has been no transmission of E. polecki between macaques and pigs in the study area.