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