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

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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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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

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

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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

A boy collects water at a new spigot in Shululu, Tajikistan. Before the government built a new water system, villagers were allocated half-hour time slots to collect water from a trickling tap. Jason Beaubien/NPR hide caption

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Nurse Marina Bogdanova, with Sputnik, gives medications to Sergei Gaptenko, who is close to finishing treatment for drug-resistant tuberculosis. Konstantin Salomatin for NPR hide caption

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Igor Davydenko sits in his cell at a Siberian prison where inmates are treated for drug-resistant tuberculosis. Konstantin Salomatin/for NPR hide caption

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Patients sit with their eyes bandaged at an Aravind Eye Care clinic in Madurai, India after cataract surgeries. Aravind performs more than 300,000 cataract surgeries annually. Reinhard Krause/Reuters/Landov hide caption

itoggle caption Reinhard Krause/Reuters/Landov

Rukshona Saidova, 12, lives with both HIV and tuberculosis. She can't walk right now because the diseases have atrophied muscles in her legs. Jason Beaubien/NPR hide caption

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Nurse Tina Martin checks on Orion Qurbonaliev, 4, who has tuberculosis. Orion's grandmother, Kholbibi Abdulloeva, also has TB. Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR