When it does cause disease, the symptoms vary depending on the patient's age and immune status. Children, especially those attending day-care centers, who have not previously been infected with CMV may become infected during the toddler or preschool years. Most people will have been infected with CMV by the time they reach puberty. CMV is excreted in urine, saliva, breast milk, cervical secretions and semen of infected individuals, even if the infected person has never experienced clinical symptoms. CMV is not spread by casual contact with infected persons.
Transmission requires repeated prolonged contact with infected items.
While most infants with congenital CMV infection will not develop symptoms, some who are without symptoms at birth will develop psychomotor, hearing, or dental abnormalities over the next several years. Prognosis for infants with profound congenital CMV infection is poor and survivors may exhibit mental retardation, deficiencies in coordination of muscle movements, hearing losses, and chronic liver disease. Infants who become infected at birth or shortly after birth from cervical secretions or breast milk from CMV-infected mothers usually do not develop symptoms. Healthy adolescents and adults who become infected will usually remain well or have a mild, nonspecific illness. Occasionally CMV infection may cause a mononucleosis-like syndrome with fever, fatigue, swollen lymph nodes and sore throat.