This human-scale lab rat cage is parked near a skate park in Denver, Colo., to make a point about the lack of science on marijuana. Richard Feldman Studio/Sukle Advertising and Design hide caption

itoggle caption Richard Feldman Studio/Sukle Advertising and Design

President Obama meets with Emory University doctors and health care workers during his visit Tuesday to the Centers for Disease Control and Prevention in Atlanta. Mandel Ngan/AFP/Getty Images hide caption

itoggle caption Mandel Ngan/AFP/Getty Images

Dr. Harold Varmus, a Nobel Prize winner, cancer biologist and director of the National Cancer Institute. Manuel Balce Ceneta/AP hide caption

itoggle caption Manuel Balce Ceneta/AP

Dr. Kent Brantly was medical director at Monrovia's only Ebola treatment center when he fell ill with the disease in July. He survived after being evacuated and treated in the United States. Courtesy of Samaritan's Purse hide caption

itoggle caption Courtesy of Samaritan's Purse

Jung Ha-yoon, 2, and other children in Seoul, South Korea, enjoy playing around (and in) ceramic jars. The country's infant mortality rate dropped 91 percent between 1972 and 2012. Jacquelyn Martin/AP hide caption

itoggle caption Jacquelyn Martin/AP

Coalitions of patient advocates now help steer research funding toward particular projects. Lilli Carré for NPR hide caption

itoggle caption Lilli Carré for NPR

President Obama spoke Tuesday about the U.S. plan to fight the Ebola epidemic in West Africa, speaking at the Centers for Disease Control and Prevention. The White House plan reportedly includes deploying 3,000 U.S. military personnel and training health care providers in Liberia. Mandel Ngan/AFP/Getty Images hide caption

itoggle caption Mandel Ngan/AFP/Getty Images

Do you know what the deadliest disease is? Hint: It's not Ebola (viral particles seen here in a digitally colorized microscopic image, at top right, along with similar depictions of other contagious diseases) NPR Composite/CDC hide caption

itoggle caption NPR Composite/CDC