Streptococcus pyogenes shouldn't be taken lightly. Left untreated, an infection with germ can trigger an autoimmune disease that damages the heart. NIAID/Flickr.com hide caption

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A doctor takes an HIV test from an athlete during the 18th National Sports Festival in Lagos, Nigeria, last December. Sunday Alamba/AP hide caption

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Camel jockeys compete at a festival on the outskirts of Saudi Arabia's capital Riyadh, a focal point for the Middle East respiratory syndrome virus. Fayez Nureldine/AFP/Getty Images hide caption

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An ambulance makes its way through revelers in Cardiff city center in Wales in 2010. New measures in the city have reduced injuries caused by violence. Matt Cardy/Getty Images hide caption

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Inspector Mohammad Saleem Taqi takes a photo of sanitation workers as they clear out debris in sewers. The government feeds the photos into a map to track the city's effort to stop dengue fever. Beenish Ahmed/NPR hide caption

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A Thai medic checks bodies for forensic identity in Phang Nga province in southern of Thailand on Jan. 11, 2005. Thousands of people were killed in Thailand after a massive tsunami struck on Dec. 26, 2004. Pornchai Kittiwongsakul/AFP/Getty Images hide caption

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Jackson Merrick, a sixth-grader from McLean, Va., says he donates half of his allowance to charity. Morgan Walker/NPR hide caption

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A Cambodian boy gets tested for malaria at a clinic along the Thai-Cambodian border in 2010. Three strains of drug-resistant malaria have emerged from this region over the past 50 years. Paula Bronstein/Getty Images hide caption

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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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The source? Signs of the Middle East respiratory syndrome virus have been detected in camels on the Arabian Peninsula. But it's still a mystery how people catch the disease. Sean Gallup/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

itoggle caption Courtesy of the Institute for Health Metrics and Evaluation

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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