Cytomegalovirus is a common virus that infects people of all ages and in all parts of the world. In the United States, between 50 percent and 85 percent of adults will be infected with CMV by the time they reach 40 years of age. However, in many other countries, most people acquire CMV as children or adolescents. Most infections with CMV are "silent," meaning the person infected has no signs or symptoms. However, CMV infection is considered a significant public health problem because it can cause disease in unborn babies and in people with a weakened immune system. These infections often can cause negative long-term outcomes, affecting one's quality of life.
Other viruses that are related to CMV include varicella-zoster virus, which causes chickenpox and shingles; Epstein-Barr virus, which causes infectious mononucleosis; herpes simplex virus, which causes cold sores and genital ulcers; and human herpes virus 6, which is associated with fever and rash in infants and young children.