Infections with Cytomegalovirus (CMV), a member of the herpesvirus family, are common in man and are usually mild and asymptomatic. However, in pregnant women, newborns, and immunocompromised individuals CMV infections may pose a significant medical risk.
The provision of seronegative blood products to selected patients remains a vital consideration in patient management. Serologic tests can be used to identify seronegative individuals5 and seronegative donors of organs or blood products. In utero infection may result in sequelae of varying degree including mental retardation, chorioretinitis, hearing loss and neurologic problems. Since the risk of in utero virus transmission
and CMV related damage of the fetus is strongly increased during primary infection, reliable recognition of primary CMV infections is of high importance for pregnant women. Thus, the presence of CMV-specific IgG antibody does not assure protection from disease. An individual may undergo primary infection with CMV, reinfection with exogenous virus or reactivation of latent virus.
If primary infection needs to be excluded, CMV IgG reactive samples should be tested for CMV IgM and CMV IgG Avidity. A positive CMV IgM result in connection with low avidity result is a strong indicator of a primary CMV infection within the last 4 months. A substantial rise in anti-CMV IgG concentrations in sequential
samples taken from an individual accompanied by the presence of anti-CMV IgM could also indicate serological evidence of active infection.
Manufacturer’s Reagent package insert, Architect CMV IgM, March 2015, Abbott Ireland Diagnostics Division, Finisklin Business Park, Sligo, Ireland.