The Evolving Relation between Humans andMycobacterium tuberculosis

Until the middle of this century, tuberculosis was, in Dickens's words, “a disease which medicine never cured, wealth warded off, or poverty could boast exemption from — which sometimes moves in giant strides, and sometimes at a tardy sluggish pace, but, slow or quick, is ever sure and certain.”1 Mycobacterium tuberculosis is an extremely successful pathogen that continues to thrive in developing countries and is reemerging in the industrialized world. Globally, it remains a more frequent cause of death than any other infectious agent.2 Approximately a third of the world's population is infected with M. tuberculosis, and the World Health . . .