The TB research ecosystem. TB is a disease fraught with complexity at every level, from the transmission, infection, and disease cycle of the host to the diverse phenotypic and genotypic variation of the pathogen. Recapitulating this complexity in a single experimental system has proven challenging, an unintended consequence being the siloing of research thrusts focusing primarily on the host (pink arrows) or the pathogen (blue arrows), seldom both, and very rarely incorporating the environments in which natural infection and disease occur.