Congenital CMV infection; diagnosis in symptomatic infants

Background: Samples from babies exhibiting clinical symptoms suggestive of congenital infection are referred regularly to NICD, New Delhi,, from Government Hospitals located in Delhi and a home for abandoned children (Palna), for the diagnosis of etiological agents like toxoplasma, rubella, CMV and herpes. Blood samples of mothers of most of the affected babies are also received. Objective: Evaluation of rapid and accurate technique for the diagnosis of congenital CMV infection. Materials and Methods: One hundred and twenty five blood samples suggestive of symptomatic congenital CMV infection were selected from samples received at NICD during the period June 2005-March 2007. A request to collect and send the urine samples of the selected babies was sent to the respective hospitals. Serum samples of the babies were tested for CMV-IgM antibodies using µ-capture ELISA. Mothers′ serum samples were subjected to CMV-IgM and IgG class antibodies assay by commercial ELISA kits. DNA isolation and amplification was performed in urine samples and some of the serum samples using a commercial PCR kit for detection of HCMV. Blood and urine samples from 20 normal babies were included in the study. Results: Twenty Seven serum samples (21.6%) of infants, of the 125 tested, were positive for CMV-IgM antibodies. Twenty five samples (20%) showed amplification of CMV -DNA. All 25 samples positive for PCR were positive for CMV IgM antibodies. Sera of 73 mothers, out of 75 tested (97.3%), were positive for CMV IgG antibodies. However, none of them was positive for CMV IgM antibodies. Mothers of all 27 positive babies were positive for CMV-IgG antibodies. Serum and urine samples from 20 normal babies were negative for ELISA and PCR. Conclusion: µ-capture ELISA technique was found to be more sensitive than PCR (92.6%) for detection of congenital CMV infection. ELISA is also rapid, less cumbersome and cost effective for diagnosis of CMV infection