Epidemiological studies on Rhodococcus equi in Taishu and Miyako native horses and their environment in Japan

Abstract

Bacteriological investigation and field survey of Rhodococcus equi infection were conducted at eight Taishu horse farms in Tsushima, Nagasaki Prefecture and at six Miyako horse farms in Miyako, Okinawa Prefecture. R. equi was isolated from ten of seventeen fecal samples (59%) and four of seven fecal samples (57%) collected from Taishu and Miyako horses, respectively, and from the all of the soil samples obtained from their environment. Of the 100 fecal and 230 soil isolates from the Taishu horse farms and of the thirteen fecal and 100 soil isolates from the Miyako horse farms, none was found to be positive for the virulence-associated antigen gene (vapA) by PCR, demonstrating that all the isolates were avirulent R. equi. According to an interview for the farmers in Tsushima and Miyako, no outbreak of R. equi infection has been identified in these areas so far.