Rapid increase in the serum Cytomegalovirus IgG avidity index in women with a congenitally infected fetus.

Background Human Cytomegalovirus (CMV) is the virus most frequently responsible for severe diseases of the fetus and newborn. The reported intrauterine transmission rate of CMV following primary maternal infection is approximately 40%. Invasive techniques are needed for the prenatal diagnosis of congenital CMV infection. Objectives The aim of this study was to evaluate whether the rapidity of change in the CMV IgG avidity index (AI) is associated with the presence of congenital CMV infection among mothers with suspected primary CMV infection. Study design The serum CMV IgG AI was repeatedly measured in 17 pregnant women with positive or borderline test results for CMV IgM together with an initial IgG AI value of <40%. Their neonates underwent polymerase chain reaction analyses for the presence of CMV DNA in the urine. The rapidity of change in the IgG AI per 4 weeks was defined as the ΔAI (%). The ΔAI of women with congenital CMV infection was compared with that of women with no infection. Results The ΔAI of nine mothers with congenital CMV infection (median,15.7%; range,7.8–42.8%) was significantly higher than that of eight mothers with no infection (median, 6.5%, range, 2.0–8.8%; p < 0.001). The incidences of congenital CMV infection were 100.0%, 16.7%, and 0.0% among mothers with a ΔAI of >10, 5–10, and <5%, respectively. Conclusions Measurement of the ΔAI in pregnant women might be useful for estimating the risk of mother-to-neonate CMV transmission. [ABSTRACT FROM AUTHOR]