Do you know what the deadliest disease is? Hint: It's not Ebola (viral particles seen here in a digitally colorized microscopic image, at top right, along with similar depictions of other contagious diseases) NPR Composite/CDC hide caption

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All folded up and ready to magnify: The Foldscope weighs less than two nickels, is small enough to fit in your back pocket and offers more than 2,000-fold magnification. TED/YouTube hide caption

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Yonta, 6, rests with her sister Montra, 3, and brother Leakhena, 4 months, under a mosquito net in the Pailin province of Cambodia — an epicenter of drug-resistant malaria. Paula Bronstein/Getty Images hide caption

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Red blood cells infected with the Plasmodium falciparum parasite. Plasmodium is the parasite that triggers malaria in people. Gary D. Gaugler/Science Source hide caption

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A health official takes a blood sample from a child's finger for a malaria test at a clinic in Bong Ti Lang village on the Thai-Myanmar border. Narong Sangnak/EPA /LANDOV hide caption

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By ensuring vaccines are invented and distributed, Bill Gates says, his foundation is dramatically reducing the number of childhood deaths in poor countries. Marie McGrory/NPR hide caption

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A pregnant Somali woman gets a tetanus shot at a clinic in Mogadishu in 2013. The vaccination initiative was launched by the GAVI Alliance, UNICEF and the World Health Organization. Carl de Souza/AFP/Getty Images hide caption

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Yonta, 6, rests with her brother Leakhena, 4 months, under a mosquito bed net in the Pailin province of Cambodia, where deaths from malaria have decreased sharply in the past two decades. Paula Bronstein/Getty Images hide caption

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Children get tested for malaria at a clinic near the Myanmar border in Sai Yoke, Thailand. Drug-resistant strains of the parasite have appeared in the region over the past few years. Surkree Sukplang/Reuters /Landov hide caption

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A health worker administers the malaria vaccine at a clinical trial in Kilifi, Kenya. Joseph Okanga/Reuters /Landov 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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