Cytomegalovirus (CMV) is a communicable DNA virus in the herpes family that when contracted in later childhood or adulthood is generally either asymptomatic or causes a short, mild illness with a fever and other flulike symptoms. It may remain in infected individuals’ systems throughout life and be excreted in their urine, saliva, breast milk, cervical secretions, and semen, even if they have never experienced symptoms. In individuals with AIDS and other patients with weakened immune systems, CMV and other viruses may cause serious and pervasive problems.