Please Explain: Tuberculosis

Tuberculosis remains one of the world's deadliest diseases--accounting for 9.4 million cases and 1.7 million deaths in 2009, according to the WHO. Maryn McKenna, science journalist and author of Superbug, and Dr. Neil Schluger, Professor of Medicine, Epidemiology, and Environmental Health Sciences at Columbia University Medical Center and Chief Scientific Officer for the World Lung Foundation, give us a history of the disease, how it spreads, why it's so hard to treat, and how drug-resistant TB has emerged and what it means for the future of treating the deadly disease.