At the Zaatari refugee camp in Jordan, many families struggle to get clean water, food and health services. Jeff J Mitchell/Getty Images hide caption

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Signs of tuberculosis have been found in ancient Egyptian mummies, such as this one in London's British Museum. Klafubra/Wikimedia.org hide caption

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Percentage of deaths each year due to neonatal disorders around the globe. Courtesy of the Institute for Health Metrics and Evaluation hide caption

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In early August, Israel launched a mass campaign to vaccinate children against polio, including this little girl at a clinic in Rahat. David Buimovitch/AFP/Getty Images hide caption

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A prostitute in Johannesburg waits for a client on a street corner. An estimated two-thirds of sex workers in South Africa are HIV positive. Yoav Lemmer/AFP/Getty Images hide caption

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A nurse takes a blood sample from Nkosi Minenhle, 15, in a mobile clinic set up to test students for HIV at Madwaleni High School in KwaZulu Natal, South Africa. Stephane de Sakutin/AFP/Getty Images hide caption

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A red blood cell infected with malaria parasites (blue) sits next to normal cells (red). NIAID/Flickr.com hide caption

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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

itoggle caption Farah Abdi Warsameh/AP