A nurse vaccinates a child against pneumonia at a healthcare center in Managua in January. Nicaragua received pneumococcal vaccines from the GAVI Alliance. ELMER MARTINEZ/AFP/Getty Images hide caption

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A man readies a cow for the International Highland Cattle Show in Glasgow, Scotland. Researchers say genetics and the amount of time animals and humans spend together can affect how viruses spread between species. Jeff J Mitchell/Getty Images hide caption

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Laurence Fishburne as Dr. Ellis Cheever and Kate Winslet as Dr. Erin Mears in the thriller Contagion. Winslet's character was modeled on CDC epidemiologist Dr. Anne Schuchat. Claudette Barius/Warner Bro. Pictures hide caption

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Two women check their cellphones as they hawk their wares on a bridge over the Artibonite River, whose waters are believed to be the source of Haiti's 2010 cholera outbreak. Nicholas Kamm/AFP/Getty Images hide caption

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Cellphones Could Help Doctors Stay Ahead Of An Epidemic

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A Remnant From Algae In Malaria Parasite May Prove Its Weakness

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Researchers hope to keep the mosquito that transmits dengue, Aedes aegypti, from infecting humans using the Wolbachia bacterium. James Gathany/CDC Public Health Image Library hide caption

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Better You Than Me: Scientists Sicken Mosquitoes To Stop Dengue

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Pakistani NGO workers protest at a rally on World AIDS Day in Peshawar in 2006. Tariq Mahmood/AFP/Getty Images hide caption

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Women hold mosquito nets after receiving them at a distribution point in Sesheke, Zambia. Researchers say malaria may have rebounded in some parts of Zambia and Senegal because of resistance to the insecticide-treated nets. ASSOCIATED PRESS hide caption

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