Mycobacterium tuberculosis complex and human co-adaptation: a two-way street complicating host susceptibility to TB.

For centuries, the Mycobacterium tuberculosis complex (MTBC) has infected numerous populations, both human and non-human, causing symptomatic tuberculosis in some hosts. Research investigating the MTBC and how it has evolved with its host over time is sparse and has not resulted in many significant findings. There are even fewer studies investigating adaptation of the human host susceptibility to tuberculosis and these have largely focused on genome wide association and candidate gene association studies. However, results emanating from these association studies are rarely replicated and appear to be population specific. It is therefore necessary to relook at the approach taken to investigate the relationship between the MTBC and the human host. Understanding that the evolution of the pathogen is coupled to the evolution of the host might be the missing link needed to effectively investigate their relationship. We hypothesize that this knowledge will bolster future efforts in combating the disease.