Regular blood transfusion therapy significantly reduces the recurrence of silent strokes and strokes in children with sickle cell anemia who have had pre-existing silent strokes, according to study results. Sickle cell disease most commonly affects African-Americans, occurring in one of every 396 births in this ethnic group. In the disease, red blood cells are hard, sticky and shaped like a crescent moon. When the sickle cells travel through small blood vessels, they can decrease the normal blood flow to all organs of the body.