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State-mandated testing for babies with hearing loss has increased early detection of a congenital and health-threatening infection that affects 1 in every 150 babies born in the U.S., a University of Utah study found.

The study, published Monday in the journal Pediatrics, examined the impact a 2013 state law had on the number of babies tested and diagnosed with cytomegalovirus, or CMV. The law requires that all infants who have failed two hearing tests be screened for the infection within three weeks of birth, unless the parents object.

Often passed to baby from mother in utero, CMV can cause hearing loss or vision loss as well as intellectual disabilities and seizures, though only 1 in 5 infected infants experience long-term health consequences, according to the Centers for Disease Control and Prevention.

But it is also common for CMV-infected infants to show no symptoms.

Researchers analyzed state Department of Health and Vital Records data for more than 500 asymptomatic infants who failed hearing tests and underwent CMV testing from July 1, 2013, to June 30, 2015. Of those infants, 234 were tested for the infection within 21 days of birth, according to the study.

Fourteen of those 234 tested positive for the CMV infection, the study found, and six had hearing loss.

Because these babies showed no symptoms, the study concluded that it was "highly likely" they would have been otherwise diagnosed much later.

And while there is currently no treatment for CMV, researchers said early diagnosis allowed for more effective health monitoring and quick intervention.

"This result has major implications for all children who fail their newborn hearing screening since speech and language outcomes depend upon early hearing-loss diagnosis," Albert Park, co-author of the study and chief of the U.'s pediatric otolaryngology division, said in a news release.

The study also identified certain populations, such as women who give birth at home, likely to benefit from bolstered state educational and outreach efforts.

Marissa Diener, the study's lead author and associate professor of the U.'s Department Family & Consumer Studies, said knowing why a child has hearing loss is invaluable for parents.

When parents "don't know why their child has hearing loss, the child is likely to be undergoing many more tests trying to find a reason and it's frustrating," Diener said. "Even if you can't treat it, at least you know the reasons."

Additionally, Park said some infected babies with hearing loss could benefit from antiviral drugs.

To address this question, Park said, the U. plans to begin a clinical trial this summer to "compare hearing, speech and language outcomes in CMV-infected infants."

Twitter: @alexdstuckey