CMV infection remains difficult to identify by symptoms alone and laboratory diagnosis is needed to establish the immune status of the patient and check for seroconversion. The immune response to CMV involves synthesis of IgM antibodies several weeks after primary infection and one week later, IgG antibodies appear.
Primary CMV infection in adults is often manifested by a mononucleosis-like syndrome and is usually self-limiting. However, in neonates and immuno compromised individuals, CMV can be debilitating and life-threatening. Seronegative women who contract the virus during the pregnancy may transmit the virus to the foetus.
Approximately 0.5 to 2.5% of newborn infants are identified each year with congenital Cytomegalovirus infection. Fewer than 5% of congenitally-infected infants develop severe disease. After primary infection, CMV enters a latent state and can be detected in B lymphocytes. Then, unlike rubella and toxoplasmosis, a reactivation (secondary infection) can occur.