A health worker injects a woman with a shot of Depo Provera, a quarterly contraceptive injection, at a health clinic in Busia, Uganda, in 2009. MCT/MCT via Getty Images hide caption

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Chhay Meth, 9, suffering through an attack of malaria at the family's home in O'treng village on the outskirts of Pailin, Cambodia, in 2009. A drug-resistant form of malaria in the region medical led officials to declare a health emergency. David Longstreath/AP hide caption

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An artist on Rio de Janeiro's Copacabana beach puts the final touches on a sand sculpture of the assassin bug, which spreads Chagas disease. The sculpture was part of an event in 2009 commemorating the 100th anniversary of the discovery of the disease. Vanderlei Almeida/AFP/Getty Images hide caption

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Eric Goosby, United States Global AIDS coordinator, says field testing is necessary and urgent to determine if HIV testing-and-treating services are feasible. Brendan Hoffman/Getty Images hide caption

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A Haitian protester in Port-au-Prince last month spray-paints a wall, equating the UN mission in Haiti (abbreviated here as MINISTA) with cholera.

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A mother held her baby as she received an experimental malaria vaccine at the Walter Reed Project Research Center in Kombewa in Western Kenya in Oct. 2009.

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Afghan men wait to receive psychiatric treatment in a Kabul hospital. Scarred by decades of war, social problems and poverty, more than 60 percent of Afghans suffer from stress disorders and mental health problems.

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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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