Natural history studies bring universal screening for congenital CMV infection closer

Slowly but surely, we are moving toward a time when universal screening of all neonates to detect congenital cytomegalovirus (CMV) infection will be routine. The reasons are well known. CMV is the commonest cause of congenital infection, damages the intellectual potential of as many babies as does Down syndrome, and is the single most common cause of sensorineural hearing loss (SNHL) in children. Performing tests for CMV in those who fail neonatal hearing screening identifies some cases of SNHL but misses the majority, because many CMV cases do not develop SNHL until later in life. Valganciclovir given within a month of birth to babies born with symptoms of congenital CMV infection reduces hearing loss, but this treatment cannot be considered in most cases of congenital infection because only a minority exhibit signs at birth. Universal screening of all babies for congenital CMV infection is predicted to be cost‐effective and even cost saving under some scenarios. Each jurisdiction responsible for considering whether a screening program should be expanded to include another condition such as CMV has a series of criteria that must be met. Congenital CMV infection meets most of these criteria already but is distinctly different from other conditions that are currently screened for; it is far more common, and most cases of CMV infection will not develop disease on follow‐up. There is thus the concern that screening for congenital CMV might swamp audiology clinics with children whose hearing remains normal, thereby worrying parents unnecessarily. The sheer number of cases of congenital CMV might also interfere with provision of services needed for children whose hearing is impaired due to any cause, which increase over the first few years of life. This potential problem could be mitigated if we could identify at birth those children who are most at risk of developing disease caused by congenital CMV, and two recent papers report important information to help achieve this. The natural history of congenital CMV infection is complex. Mothers can experience primary infection, reactivation of latent CMV, or reinfection with a new strain of CMV during pregnancy (the latter two pooled under the term recurrent infection). The addition of antibody avidity tests to those for CMV IgG and IgM antibodies has improved the ability to differentiate primary infection from recurrent infection caused by either reactivation or reinfection. Several years ago, this journal published a review of the complex relationship between maternal seropositivity and the incidence of congenital