 In countries where "M. africanum" is endemic, it represents an important opportunistic infection of the later stages of HIV disease.It is not fully understood how the genetic differences between "M. africanum" and "M. tuberculosis" give rise to the lower pathogenicity of the former.However, it is known that the Region of Difference 9 (RD9) is lacking in "M. africanum" but present in "M. tuberculosis".