Identification of Zoonotic Balantioides coli in Pigs by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and Its Distribution in Korea

SIMPLE SUMMARY: Balantioides coli is a protozoan parasite that can infect humans, and its main reservoir is pigs. Recent studies suggested that one of B. coli variants, named variant A, has zoonotic potential. Previous studies have reported B. coli infection in pigs in different countries; however, the prevalence of the zoonotic variant is limited due to a lack of molecular information. In this study, we developed a molecular technique-based method that could differentiate B. coli variant A from B without sequence analysis. Using the method, 174/188 (94.6%) pig fecal samples collected in domestic pigs in Korea were positive for B. coli, and of the samples, 62 (33.7%) were the zoonotic variant. To our knowledge, this is the first study to develop a method to differentiate B. coli variants A and B without sequence analysis and to assess the molecular epidemiology of B. coli in pigs. ABSTRACT: Balantioides coli is a zoonotic protozoan parasite whose main reservoir is pigs. Recent studies have shown that B. coli variant A but not B has zoonotic potential. While B. coli infection has been reported in different animals and countries, the prevalence of the zoonotic variant is limited due to a lack of molecular information. Therefore, this study investigated the prevalence of B. coli in domestic pigs in Korea and assessed its zoonotic potential. A total of 188 pig fecal samples were collected from slaughterhouses in Korea. B. coli was identified by microscopy and molecular methods. B. coli was identified in 79 (42.9%) and 174 (94.6%) samples by microscopy and polymerase chain reaction (PCR), respectively. This study also developed a PCR-restriction fragment length polymorphism (PCR-RFLP) method to differentiate B. coli variant A from B without sequence analysis. Using this method, 62 (33.7%) and 160 (87.0%) samples were positive for variants A and B, respectively, and 48 (26.1%) samples were co-infected with both variants. Sequence and phylogenetic analyses showed a high genetic diversity of B. coli in pigs in Korea. To our knowledge, this is the first study to develop a method to differentiate B. coli variants A and B without sequence analysis and to assess the molecular epidemiology of B. coli in pigs. Continuous monitoring of zoonotic B. coli in pigs should be performed as pigs are the main source of human balantidiasis.