Positive IgM in Congenital CMV Infection

Neonatal serum detection of cytomegalovirus (CMV) immunoglobulin M (IgM) has low sensitivity in identifying congenital cytomegalovirus (cCMV). Several reports have endeavored to associate the presence/absence of IgM to disease severity. Data were collected for all infants with cCMV followed in our clinic. Infant outcome after birth was compared between infants who tested positive or negative. Sensitivity of positive IgM in diagnosing cCMV was 40.7%. The rate of symptomatic disease in those who tested positive was statistically higher (67.7%, P <.001). Odds ratio for symptomatic disease in infants with positive IgM born after a maternal primary infection was 3.47 (95% confidence interval = 1.7-7.1). Positive IgM was found in only 48.8% of symptomatic and 22.1% of asymptomatic children. Our results demonstrated a low sensitivity of IgM in diagnosing cCMV. However, while a positive IgM antibody for CMV is associated with a more symptomatic disease, it does not serve as a precise laboratory marker for a severity.