Participants will be screened with a standard donor questionnaire. It asks about their health and past medical problems. It also asks about risky behaviors that could increase their exposure to viruses or bacteria that could be transmitted through a transfusion. Participants will give a blood sample to make sure they are able to donate. They will have a physical exam. A finger stick test will check their hemoglobin, or red blood cell, level. They might give a urine sample.