A microbiologist tests samples for Influenza A (H1N1), formerly referred to as swine flu, at the Dallas Department of Health and Human Services laboratory in Dallas, Texas May 1, 2009. A rapidly spreading flu outbreak may quickly overload a U.S. health system already straining from hospital closures, cuts in public health funding, a nursing shortage and too many uninsured patients, health experts said on Friday. REUTERS/Jessica Rinaldi (UNITED STATES SOCIETY HEALTH)