Narrator: This is Science Today. Since tuberculosis is rampant in much of the developing world and immigration from these countries to the U.S. is at an all-time high, public health officials have called for large-scale TB screening programs in cities with large immigrant communities and at national borders. Joel Ernst, an infectious disease specialist at the University of California, San Francisco says tourism has also caused a resurgence of TB in this country.

Ernst: And so as we become a globalized human population, the exposure and the likely risk of tuberculosis is substantially greater than when we were largely staying at home on the north American continent.

Narrator: Although the development of anti-tuberculosis antibiotics in the Fifties caused TB to fall from the American consciousness, it never really went away in the rest of the world.

Ernst: In the developing world, tuberculosis is still incredibly prevalent and at least an estimated three million people a year die of tuberculosis. So this is really a disease that never really went away.

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