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CMV: A Leading Cause of Newborn Hearing Loss that You’ve Never Heard Of

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CMV: A Leading Cause of Newborn Hearing Loss that You’ve Never Heard Of

Sep 19, 2017

Infection from a common virus, cytomegalovirus (CMV), is the leading cause of non-genetic hearing loss in U.S. newborns. Even though the virus is far more prevalent than Zika, it remains relatively unheard of. ENT specialist Dr. Albert Park explains what can happen when infants are exposed to CMV while in the womb and steps that pregnant women can take to avoid infection. Park is carrying out a national clinical trial to determine whether he can lessen the impact of CMV in infants by treating them with antiviral medications.

Episode Transcript

Interviewer: There's a cause for hearing loss in children that might be entirely fixable. We'll talk about that next on The Scope.

Announcer: Examining the latest research and telling you about the latest breakthroughs. The Science and Research Show is on The Scope.

Interviewer: I'm talking with Dr. Albert Park about cytomegalovirus. It turns out that cytomegalovirus or CMV is really pretty common and a lot of us are probably infected with it but don't even know it. But it's a different story for newborns, right? What happens there?

Dr. Park: Yes. So many of us may get the infection, maybe when we were toddlers or later in life. And so, especially in underserved areas, you could have prevalences of as high as 80% or 90%. In Utah, it's much lower, but still a significant number of the adult population here has been exposed to this virus. Fortunately, when you get it, when you're older maybe you may have a bit of a runny nose, a cough, but really no other significant symptoms.

The problem really is in the unborn child. So if a mother contracts the infection during her pregnancy, unfortunately that virus then can be passed on to the unborn child, and then that child can really develop devastating and very severe problems from this infection. It can range from unfortunately fetal demise or death to less severe but still really impactful conditions, such as brain defects, hearing loss, developmental delay issues, speech and language. And so, because I'm a pediatric ear, nose, and throat physician interested in hearing loss and because hearing loss is a really big factor in this infection, that's how I became involved in this.

Interviewer: So if this virus is so common and so easily transmissible, why have we not really heard more about it before?

Dr. Park: Oh, that's a great question. I don't know. I mean, I know that, for instance, Down syndrome, spina bifida, other conditions are actually much less common than cytomegalovirus, have a lot more press and a lot more awareness. It's interesting that Zika, which is a huge issue globally and it certainly is, but actually, cytomegalovirus, which also causes microcephaly and central nervous system abnormalities is a bigger problem in the United States and in Utah than Zika is.

Interviewer: And so is it that every unborn child that's infected with CMV has birth defects?

Dr. Park: So the numbers are that it's believed that congenital CMV can affect as high as maybe 0.5% to 1% of all live births, so it's a huge number of children who are exposed and can be infected. Fortunately, the majority of these children will develop the infection but not develop any disease. So they won't develop CNS or central nervous system problems. They won't develop severe hearing or mental, sort of, developmental problems.

But in a significant number of these children, unfortunately, that can occur. I think our task as providers and as parents is to really be aware of this condition. There are very good approaches that one can do when you're pregnant to minimize the risk to your unborn child. The sort of a classic scenario would be that a mother may have an older child, maybe two or three, who unfortunately gets the infection and that child doesn't have any problems. But then that child, maybe when, at two or three, then passes on the infection to the mother and it's passed through contact exposure so that could be, maybe in sharing utensils, kissing on the lips, playing with toys. And again, if the child puts the toy in his or her mouth and somehow that then gets into the saliva of the pregnant mother, that can cause infection.

So simple as hand washing is really crucial. Not partaking in sort of practices that can increase your risks of transmission have been shown to be very helpful in reducing the risk of developing it to the unborn child.

Interviewer: And now, you're taking this even one step further and you hope to be able to treat these children who have tested positive for CMV and have hearing loss. What are you doing there?

Dr. Park: I think what has been the controversy, at least, among the American Academy of Pediatrics and other societies is whether treatment of some sort could be effective. And so we have really wanted to answer that question. The question, really being, could a medication such as an antiviral possibly improve the hearing outcomes or at least prevent the progressive hearing in these children with congenital CMV. There is some data from some other studies showing that severely affected children with congenital CMV when treated with this antiviral medication, they had better hearing and neurocognitive or mental, sort of, developmental outcomes.

But the question really is this large group of children with just hearing loss from congenital CMV, what could an antiviral potentially provide for them? And so we are embarking on an NIH-funded clinical trial. It will involve about 30 different sites. So this will be a national study. And what we're going to try to determine is whether the antiviral treatment will provide better hearing outcomes or speech and language outcomes compared to children who do not undergo the treatment. If we are able to demonstrate this and that, I think, could change the, sort of, picture of CMV testing around the country and may even push us toward universal screening.

Interviewer: And so what is your hope with these different efforts that you're involved in? But you know, what do you hope to accomplish?

Dr. Park: Well, I think there's a number of sort of goals. I think, one is I would love it so that every family when I go down the street and bump into them know what congenital CMV is, that they know that, you know, simple hand washing and measures to prevent the transmission and the infection can be done and that they do this on a regular basis, that in those children who are identified that these kids are all being identified so we have a screening program that's nationally available to do this. And if we are able to find an intervention like an antiviral that prevents further progress or worsening the hearing, that the families and the children have the opportunity to have that treatment available to them.

Announcer: Interesting, informative, and all in the name of better health, this is The Scope Health Sciences Radio.