The Absence of Rhodococcus equi in Mongolian Horses

Abstract

ABSTRACT. In native Mongolian horses, the incidence and distribution of Rhodococcus equi are poorly understood. One hundred and fourteen equine fecal samples and 71 soil samples were collected from the camp sites of 26 nomadic families located in three areas less than 100 km from Ulaanbaatar, Mongolia. Five fecal samples were also collected from foals of Przewalski's Horses introduced into the Hustai National Park, Mongolia. No R. equi was isolated from the Mongolian horses or the soil samples. However, three colonies of R. equi were isolated from two fecal samples collected from foals of Przewalski's Horses. These isolates were avirulent, with neither 15-to 17-kDa antigens (VapA) nor a 20-kDa antigen (VapB) genes being detected. We concluded that native Mongolian horses and their environment appear free from contamination with R. equi.

Rhodococcus equi in the Soil Environment of Horses in Inner Mongolia, China

“…Moreover, the isolation rates and the mean number of R. equi from Tongliao City were significantly greater than those from the grasslands of Inner Mongolia. These data contrast with those of our recent study in which R. equi was absent from Mongolian horses in Ulaanbaatar, Mongolia [15].…”

“…Our recent study showed no evidence of R. equi in either fecal samples of Mongolian foals or soil samples collected from the environments in which they were held by 26 nomad families in Ulaanbaatar. Avirulent R. equi were isolated only from the feces of descendants of introduced Przewalski's Horses at Hustai National Park [15]. In the present study, we were able to isolate R. equi from soil environment of horses at the Hulun Beier and Xilin Goler grasslands of Inner Mongolia, but no virulent R. equi were found in those isolates.…”

“…The presence of a 90 kb type-II plasmid in Korean and Japanese isolates also partially supports a common origin and ancestry of the native horses of northeast Asia [17]. More recently, we investigated soil samples and the feces of foals raised by nomadic families camped in three areas less than 100 km from Ulaanbaatar, Mongolia [15]. However, no R. equi was isolated from the feces of Mongolian native horses.…”

“…To test the hypothesis that the transmission to Japan of the virulent form of R. equi and its associated virulence plasmids may have occurred with the migration of native horses from the Mongolian grasslands via China and the Korean Peninsula, we sampled the environments of Cheju horses in Korea and Mongolian horses at Ulaanbaatar in Mongolia for isolation of R. equi [12,15,17]. Our recent study showed no evidence of R. equi in either fecal samples of Mongolian foals or soil samples collected from the environments in which they were held by 26 nomad families in Ulaanbaatar.…”

Plasmid Profiles of Virulent Rhodococcus equi Strains Isolated from Infected Foals in Poland

“…Results of studies undertaken with strains isolated in Japan and Korea suggest their common origin [ 21 ]. According to Takai et al [ 32 ] one of the possible explanation may be a historical introduction of both type strains into these countries through Mongolian horses. However, there are no data at the moment about plasmid profiles of R .…”