For years, the use of unscreened blood transfusions exposed severely wounded servicemembers and other trauma patients in Iraq and Afghanistan to the inherent risk of diseases such as HIV, hepatitis and malaria, according to medical experts who advise the secretary of defense. Battlefield attacks that resulted in mass casualties or severe injuries often overtaxed the military’s blood supply system until 2007, meaning medics collected fresh blood from those on site for emergency treatment of the wounded, the Defense Health Board wrote in a June 2008 report. The unscreened blood transfusions, however, did not meet federal safety standards required of all...