Rhodococcus equi infection in Japanese Black Cattle in Japan: 12 case reports and literature review

In 2015, the third novel virulence plasmid pVAPN of Rhodococcus equi was discovered in bovine isolate from Ireland. The first bovine case of R. equi infection in Japan was reported in 2018 at a meat inspection station in Yokkaichi, Mie Prefecture, involving a Japanese Black heifer. Subsequently, additional cases were reported through annual surveillance in Miyazaki's prefectures, Oita, Shiga, Gifu, Aichi, and Kyoto City, bringing total number of confirmed cases to 12. This review provides an overview of host-associated virulence plasmids of R. equi, a brief history of bovine R. equi case reports in Japan, and data analysis on the occurrence, clinical signs, and pathological findings of these 12 cases, along with a discussion on infection mechanisms and pathogenesis.