A Public Health Agency of Canada worker seen inside the National Microbiology Laboratory's Level 4 lab in Winnipeg. Public Health Agency of Canada/Nature hide caption

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Dr. Bruce Ribner, medical director of Emory University Hospital's infectious disease unit, embraces Dr. Kent Brantly (left) who was treated with an experimental Ebola medicine and released from the Atlanta hospital Thursday. John Bazemore/AP hide caption

itoggle caption John Bazemore/AP

Truvada, an FDA-approved drug to help prevent HIV infection, is among the AIDS drugs that fill pharmacy shelves at the Whitman-Walker clinic, a Washington, D.C., community health center. Astrid Riecken/MCT/Landov hide caption

itoggle caption Astrid Riecken/MCT/Landov

David Chance recuperates at Oregon Health and Science University. Kristian Foden-Vencil /Oregon Public Broadcasting hide caption

itoggle caption Kristian Foden-Vencil /Oregon Public Broadcasting

I'm not trying to lead you astray. It's just that scientists are not skeptical enough about their mouse studies. iStockphoto hide caption

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Andrew Witty, CEO of GlaxoSmithKline, says that better control of infectious diseases in Africa is allowing chronic diseases to come to the surface. Mark Lennihan/AP hide caption

itoggle caption Mark Lennihan/AP