Use of stored dried blood spots for retrospective diagnosis of congenital CMV

The diagnosis of congenital cytomegalovirus infection cannot be made with certainty in children presenting after the perinatal period, unless stored early samples are available for diagnostic testing. This has led to uncertainty in confirming the overall contribution of CMV to hearing loss and neurodevelopmental impairment. The use of dried blood spots (DBSs) to retrospectively diagnose infection in children with compatible symptoms may be helpful diagnostically although there are ongoing uncertainties regarding the stability of viral DNA in cards, the risk of contamination between cards, and sensitivity and specificity in a clinical setting. This report aims to address these areas and evaluate the use of DBS testing in our hands in the United Kingdom to date. Results from testing artificially prepared cards and cards from three populations of children suggest a high specificity for congenital CMV infection and a good sensitivity for cases where sensorineural hearing loss is caused by congenital CMV.