Biohazard suits used to handle dangerous microbes hang in a laboratory at the U.S. Army Medical Research Institute of Infectious Diseases in Fort Detrick, Md. Patrick Semansky/AP hide caption

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An outbreak of bird flu in India in 2008 prompted authorities to temporarily ban the sale of poultry. Diptendu Dutta/AFP/Getty Images hide caption

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People wait in line at the Durham County Health Department for the H1N1 flu vaccination in Durham, N.C., in November 2009. Gerry Broome/AP hide caption

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