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

itoggle caption Patrick Semansky/AP

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

itoggle caption Diptendu Dutta/AFP/Getty Images

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

itoggle caption Gerry Broome/AP

Cambodian women wear masks as they walk in a market in Phnom Penh in Oct. 2009. That month a second Cambodian died from swine flu, health officials said. Tang Chhin Sothy/AFP/Getty Images hide caption

itoggle caption Tang Chhin Sothy/AFP/Getty Images