A well-wisher uses his phone to take a picture of a banner of photos of Nelson Mandela outside the Mediclinic Heart Hospital in Pretoria, where the former South African president is being treated. Ben Curtis/AP hide caption

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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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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

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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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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

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Health workers vaccinate a boy against polio at a May immunization drive in Mogadishu, Somalia. Farah Abdi Warsameh/AP hide caption

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Boys at the L'Ecole Les Freres Clement elementary school in Jacmel, Haiti, line up to take deworming pills that protect against elephantiasis. Maggie Steber for The Washington Post/Getty Images hide caption

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Oxana and Pavel Rucsineanu walk to the tuberculosis hospital in Balti, Moldova. Oxana and their new baby live in an apartment, but Pavel still has to stay at the TB ward, fighting for his life. Jason Beaubien/NPR hide caption

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A health worker weighs a Somali baby on scales at a medical clinic in Mogadishu. Babies in Somalia have the highest risk of dying within the first 24 hours after birth. Carl de Souza/AFP/Getty Images hide caption

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A baby receives a polio vaccine at the Medina Maternal Child Health center in Mogadishu, Somalia, on Wednesday. Somalia has one of the lowest immunization rates in the world. Ben Curtis/AP hide caption

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An extract of sweet wormwood has been used in China for thousands of years to treat malaria, but being able to make mass quantities of the extract has been elusive, until now. Sarah Cuttle/Getty Images hide caption

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Dengue fever patients are treated in a hospital in Asuncion, Paraguay, in January. Norberto Duarte/AFP/Getty Images hide caption

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