The spread of viruses through transfusions is the cause of serious illness and death in recipients whose immune systems are unable to fight infection. Another group of patients whose immune systems are underdeveloped and can be affected by a particular virus known as cytomegalovirus (CMV) is low birthweight infants (LBWIs). CMV can be spread through the placenta, during the birth process, through breast milk, while in the hospital or while caring for someone carrying the virus as well as through a transfusion, known as transfusion-transmitted (TT-CMV).