The bite of a cobra can paralyze its victims and, if enough venom is released, fatally stop their breathing. It's estimated that more than 75 percent of patients in India who die from a snake's bite never make it to the hospital. STRDEL/AFP/Getty Images hide caption

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Ali Maow Maalin said he avoided getting the smallpox vaccine as a young man because he was afraid of needles. He didn't want others to make the same mistake with polio. Courtesy of the World Health Organization hide caption

itoggle caption Courtesy of the World Health Organization

A mother and daughter walk home after attending a community meeting about eradicating female genital mutilation in the western Senegalese village of Diabougo. Finbarr O'Reilly/Reuters /Landov hide caption

itoggle caption Finbarr O'Reilly/Reuters /Landov

A Yemeni child receives a polio vaccine in the capital city of Sanaa. The Yemen government launched an immunization campaign last month in response to the polio outbreak in neighboring Somalia. Mohammed Huwais/AFP/Getty Images hide caption

itoggle caption Mohammed Huwais/AFP/Getty Images

Vaccines against the HPV virus are already used to prevent cervical and anal cancer. Harry Cabluck/AP hide caption

itoggle caption Harry Cabluck/AP

Children with tuberculosis sleep outside at Springfield House Open Air School in London in 1932. Like sanatoriums, these schools offered TB sufferers a place to receive the top treatment of the day: fresh air and sunshine. Fox Photos/Getty Images hide caption

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Pandoraviruses were discovered lurking in the mud of Chile and Australia, half a world apart. courtesy of Chantal Abergel and Jean-Michel Claverie hide caption

itoggle caption courtesy of Chantal Abergel and Jean-Michel Claverie

A Doctors Without Borders support counselor waits for MDR-TB patients at a clinic in Nukus, Uzbekistan. Courtesy of Misha Friedman hide caption

itoggle caption Courtesy of Misha Friedman

Dale Hippensteel, manages the Sheboygan County health department. Jeffrey Phelps/For NPR hide caption

itoggle caption Jeffrey Phelps/For NPR

People living in affluent neighborhoods in north central Dallas were most likely to get infected in 2012. Those neighborhoods were also hit hardest in the 2006 outbreak. JAMA hide caption

itoggle caption JAMA

Red blood cells are normally shaped like doughnuts, but sickle cells (purple) are flattened and clump together. NIH hide caption

itoggle caption NIH

A woman waits to get AIDS drugs on April 8 at a clinic in Ga-Rankuwa, South Africa, about 55 miles north of Johannesburg. New WHO guidelines say patients should start HIV treatment much earlier, before they become extremely sick. Stephane de Sakutin/AFP/Getty Images hide caption

itoggle caption Stephane de Sakutin/AFP/Getty Images