Prevalence and molecular identification of Balantioides coli isolates from pet guinea pigs in Central China

Balantioides coli is the only known zoonotic ciliate that can infect humans and is usually acquired from swine. It has, however, been reported in other mammals, including guinea pigs, where infection prevalence and molecular characterization are relatively unknown. In the present study, 32 guinea pigs from two different pet markets in Luoyang city of the Henan province in China were evaluated for ciliate-like trophozoites or cysts by direct fecal smear microscopy. Positive samples were further characterized using 18S rDNA and ITS1-5.8S rDNA-ITS2 sequence analysis. Microscopy indicated that ciliate-like cysts were observed in the fecal samples of several guinea pigs, were spherical in shape, and exhibited sizes of 40-65 μm in diameter. The average cyst-positive prevalence in guinea pigs was 62.5%. Sequence analysis indicated that the guinea pig-derived ciliate isolates belonged to B. coli and included two genetic variants (A and B), of which genetic variant A was more dominant among the guinea pig samples. To the best of our knowledge, the present study is the first molecular identification of B. coli in guinea pigs and provides some important information for investigating the molecular epidemiology of B. coli.