APPLICATION: 1. CMV IgM can appear in both primary and reactivated CMV infections and can persist for extended periods after a primary infection. 2. Patients with EBV induced Infectious Mononucleosis may produce heterotrophic IgM resulting in a false positve CMV IgM.
INTERPRETATION: CONGENITAL CMV INFECTION 1. CMV is the most common cause of congenital disease of the new-born in developed countries, affecting 0.5 to 2% of all live births. Approximately 10 to 15% of congenitally infected infants will present with major symptoms. The biggest risk to the foetus is from a primary CMV infection whilst reactivation and reinfection pose a much reduced risk to the foetus.
2. The routine test for diagnosis of CMV is the detection of specific IgM. This is not specific for CMV infection nor does it distinguish primary infection from reactivation. The best way to confirm primary infection is to demonstrate seroconversion from IgG negative to IgG positive.
