Mere contact with M. tuberculosis doesn’t mean that an active case of tuberculosis will follow. After inhalation, the invaders travel until they reach cavities deep within the lungs. There they invade cells involved in immune response; those cells then invite reaction from other types of cells in the immune system, forming clumps in which the infected cells can fall into dormancy, becoming a latent TB infection. Most otherwise healthy people will never develop active disease. But for about one in ten, the infection flares, producing tissue damage around each clump. Sometimes the immune system can mount another counterattack, and the disease may wax and wane. Left untreated, active TB is the stuff of nightmares: up to two-thirds of its victims will die if no help comes to them.

That help has been available for almost sixty years. But not for seventeen desperately ill people in the Eastern Cape province of South Africa whose fate suggests that we may not enjoy our sense of invulnerability in the face of TB—and other infectious diseases we’ve conquered—for that much longer. Those afflicted suffer from a strain of tuberculosis that seems to resist every drug available to treat it. Seventeen is a tiny number, but the question those desperately ill people embody is whether we will do what is necessary to keep their numbers so small.

via New Life for a Deadly Disease: The Threat of Drug-Resistant Tuberculosis : The New Yorker.