Nina Pham, 26, steps off a plane Thursday night at a municipal airport in Frederick, Md. An ambulance was waiting to take her to the National Institutes of Health in Bethesda, Md. Paul J. Richards/AFP/Getty Images hide caption

itoggle caption Paul J. Richards/AFP/Getty Images

Victoria Ruiz (left), a postdoctoral fellow in immunology, works with Brianna Delgado, a high school student that she mentors, at the Blaser Lab, inside NYU's Langone Medical Center in New York, NY. Ramsay de Give for NPR hide caption

itoggle caption Ramsay de Give for NPR

The Clinical Center at the National Institutes of Health in Bethesda, Md. National Institutes of Health hide caption

itoggle caption National Institutes of Health

Two chimps groom each other at the Save the Chimps facility in Florida. The National Institutes of Health owns about 360 chimpanzees that aren't yet retired and that are living at research facilities; new guidelines say most of its chimps should be retired. Save the Chimps hide caption

itoggle caption Save the Chimps