Narrator: This is Science Today. Every year, seven to eight million people worldwide become sick with tuberculosis and more than three million die from the disease. All in all, TB kills more people than any other infectious disease, including AIDS and malaria combined. Now, with the advent of several antibiotic-resistant bacterial strains, TB has become a global epidemic. Dr. Joel Ernst, an infectious disease specialist at the University of California, San Francisco, says for years TB was thought to have been conquered.

Ernst: It certainly fell from the American consciousness, at least most of American's consciousness, after about the 1950s or so. Tuberculosis sanitaria were closed because they weren't necessary anymore. Anti-tuberculosis treatment was given as an outpatient and most people with tuberculosis who received those drugs were cured.

Narrator: Today however, stealthy strains of the microbe that causes TB, have brought the disease back to pre-antibiotic days in many parts of the world, including New York and other parts of this country.

Ernst: The best chance of defeating it is going to be through the development of a more effective vaccine.

Narrator: For Science Today, I'm Larissa Branin.