Congenital CMV infection often goes undetected because the majority of affected infants do not present symptoms at birth; routine screening of newborns could allow infected infants to receive better care.

The first law in the U.S. mandating CMV testing took effect in Utah last July. It requires urine or saliva tests for newborns who fail two infant hearing screenings. Lawmakers in Connecticut and Illinois have introduced similar legislation in 2014, but in both states, the bills have so far failed to pass.

Newborn screening tests for illnesses that, while rare, can be treated or managed to minimize impact. Each state runs its own newborn screening program, with the types of testing varying from state to state. In addition to mandatory hearing tests, states rely on a dried blood spot assay which screens for multiple conditions in parallel. While CMV is among the most common congenital infections in the U.S., outside of Utah, CMV testing is not yet required by law.

Challenges to CMV screening are largely practical – CMV viral load is low in blood, and as a result, it is a poor fit for the routine blood tests that are a fixture of newborn screenings today. CMV is best detected using saliva or urine-based assays – however, screening based on urine or saliva has the considerable disadvantage of requiring the establishment of an infrastructure for collecting and transporting specimens – mandating a new and distinct test for all infants would require sweeping legislative changes and could face resistance from an already strained healthcare delivery system. Adding to the challenge, because CMV is a congenital infection, a proper diagnosis can only be made if the CMV virus is detected within a week of birth.

Researchers estimate that, because of onset later in life, only about half of the hearing loss resulting from congenital CMV infection is detected by universal newborn hearing screening. As a result, much of the hearing loss and many other CMV-related disabilities remain undetected for years after birth and are never linked to congenital CMV infection, and are therefore not optimally managed.

Lacking mandatory testing, hospital administrators may consider adopting voluntary screening for congenital CMV, along with a standardized follow-up procedures to monitor the impact of early diagnosis. Each year, approximately 5,000 U.S. infants will develop permanent problems due to CMV, some of them severe, including deafness, blindness, and mental retardation.