Congenital Cytomegalovirus Infection: Time to Test Newborns?

“It is estimated that up to 30% of the time when hearing loss develops within the first two years of life, the child passed their newborn hearing screen, lulling physicians into a false sense of security,” said Diego Preciado, MD, PhD, an otolaryngologist and director of the Cochlear Implant Program at Children’s National Medical Center in Washington, D.C. “If you’re going to screen for CMV, one should really consider screening every newborn, not just those with identified hearing loss. The issue is whether this approach would be considered cost-effective.”

“For any newborn screening program to be successful and embraced into practice, it has to be inexpensive,” said Mark Schleiss, MD, co-director of the Center of Infectious Diseases and Microbiology Translational Research at the University of Minnesota in Minneapolis. “The good news is that the technologies exist to use dried blood spot testing to quickly and inexpensively get an answer. The downside is that newborn blood spot screening may not the best way to screen for CMV.” Recent studies show that dried blood spot testing is cheap and convenient but not as accurate as testing urine or saliva (JAMA. 2010;303:1375-1382).

But CMV testing is cheaper than genetic testing and, given the prevalence of CMV-related SNHL, Dr. Park believes CMV testing is a cost-effective strategy. “We found that if you incorporate CMV testing first, instead of doing genetic testing or imaging first, it’s cost-effective in this population of children. CMV testing is actually the least expensive diagnostic test to detect causes of hearing loss than all the other tests that are currently being done,” he said.

Still, the lack of a standard treatment protocol causes some clinicians to wonder if CMV testing should be performed on all infants. “The treatment holds promise, but it’s nonstandard at this point,” said Dr. Preciado. “So, should CMV testing be legislated, especially when the legislation includes language that requires pediatricians to introduce a discussion about treatment if the test comes back positive? That’s certainly controversial.”

Testing all babies for congenital CMV would offer increased opportunity for early detection and potential treatment of hearing loss, but it would also certainly turn up babies who have congenital CMV but no adverse symptoms. And while many clinicians believe the risk-benefit ratio of valganciclovir treatment tilts in favor of treatment for infants with CMV-related hearing loss, treating asymptomatic, congenital CMV-positive infants is more problematic.

“Valganciclovir can result in adverse side effects. Short-term adverse effects include neutropenia and elevated transaminases; long-term effects may include increased risk for cancer and infertility, which have been reported in animals but not children. So if you have an asymptomatic patient and expose them to those side effects, the risk-benefit calculation doesn’t really work out,” Dr. Park said. A better approach, he said, would to be conduct frequent hearing tests and intervene if the child’s hearing begins to deteriorate.

The Future

The CMV and Hearing Multicenter Screening (CHIMES) study, currently in progress, is expected to provide some clarity regarding CMV testing and infant hearing. The seven-year study will screen 100,000 newborns for congenital CMV infection and correlate that information with the results of newborn screening programs. It will also follow children with congenital CMV for four years to determine the natural history of CMV-related hearing loss. Study results are expected to add clarity to future discussions on the utility of CMV testing in the effort to preserve hearing.