China Case Control Avian Influenza

This study will determine risk factors of human infection with avian influenza A virus, also known as bird flu virus. Certain risk factors such as exposure to poultry, travel history, health status, and other factors may affect one's risk of getting bird flu. Study participants will include individuals, older than age 1, that tested positive for influenza A (H5N1) in a previous surveillance program and controls (individuals that have not tested positive for avian influenza A (H5N1) and have no fever or respiratory symptoms). There will be 1 study visit during which volunteers will be asked detailed questions about their health, work, and travel habits. Study participants will be asked to donate a blood sample to test for antibodies, the part of the blood that fights infection.