A virus (viral infecton) that infects 50-85% of adults in the US by age 40 and is also the virus most frequently transmitted to a child before birth. Persons with symptoms have a mononucleosis-like syndrome with prolonged fever and mild hepatitis. Once a person becomes infected, the virus remains alive and usually dormant within that person's body for life. Recurrent disease rarely occurs unless the person's immune system is suppressed due to therapeutic drugs or disease. CMV infection is therefore a concern because of the risk of infection to the unborn baby, people who work with children, and immunodeficient people such as transplant recipients and those with HIV.