Cytomegalovirus (CMV), a member of the virus family Herpesviridae, is the most common viral infection in humans. In healthy individuals, it is usually asymptomatic or accompanied by mild fever and fatigue, and may persist as a latent or chronic infection. However, in individuals with a compromised immune system, such as those suffering from AIDS, CMV infection is accompanied by a wide range of life threatening symptoms. Congenital transmission of CMV occurs most often during primary infection, and can result in severe disability and even death for the unborn child.
During primary CMV infection, IgM antibodies can be detected during the first 2-3 weeks and can persist for 6-9 months. IgG antibodies are produced following acute infection and remain detectable for life. During virus reactivation, IgM levels may increase again, and thus the most reliable method of identifying primary infection is by seroconversion of IgG. Congenital transmission occurs most often during primary infection of a pregnant woman. Therefore, serological procedures that detect and distinguish between IgM and IgG anti-CMV antibodies are an important aid in the discrimination of primary and recurrent CMV infections, especially during pregnancy.