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CMV: Hiding in Plain Sight

By Esther Entin, MD

Cytomegalovirus (CMV) is the most common congenital (present at birth) virus in the US. Most healthy people who get CMV after birth have no long-term problems, but when developing fetuses are infected, the consequences range from mild to severe, including the potential for life-long disability.

Of the 30,000 newborns born each year with congenital CMV, about 5500 have permanent problems. There are ways for mothers-to-be to protect themselves from contracting the virus, and it pays to know the ways to safeguard yourself and your unborn child.

Cytomegalovirus is a member of the herpes virus family, which includes herpes simplex, chicken pox, Epstein-Barr viruses and others. It is transmitted from person to person by contact with virus containing secretions including saliva, urine, sexual fluids and blood products. It is not transmitted by food, water, or animals.

After a first-time infection, CMV remains dormant in one’s system for life, and the virus can be shed in body fluids from time to time without any symptoms. Although most people remain asymptomatic, the virus can be reactivated, particularly when one's immune system is suppressed, such as by cancer treatment or HIV infection.

Mothers Often Are Infected by Their Children

Infected children shed the virus for longer than adults. It is very common for them to spread CMV in their households and child care centers as the virus is excreted in the urine or saliva of 30-40% of young day care attendees. Thus young children can transmit the virus to their parents, other day care staff, and each other, through drooling, mouthing toys, wetting diapers, and immature hygiene practices.

CMV is particularly dangerous to developing fetuses. It can be transmitted during pregnancy by crossing from the mother through the placenta to the developing fetus. Congenital infection can occur during any trimester and can be the result of a new infection or a reactivation of a latent maternal infection. The most severe consequences of CMV occur when the mother has her first CMV infection during the first half of the pregnancy. When a baby is infected in utero, it has a 10-15% rate of congenital CMV if it is the mother's first infection and a 1% rate if it is a reactivation of a dormant infection in the mother.

CMV can also be transmitted from mother to child during delivery through the birth canal by contact with infected cervical and vaginal secretions, and ingesting breast milk that is contaminated with CMV after birth. When full term infants acquire CMV during delivery or from human milk, they do not usually develop symptomatic illness or later disability.

Signs and Symptoms of CMV

It is common for those who have the virus to be largely symptom-free, but children and adults may feel rundown, and have fevers, loss of appetite, muscle aches, or swollen glands, especially in the neck, from three to twelve weeks after exposure. Rare complications include colitis, neurologic complications, inflammation of the heart or heart lining, pneumonia, and rupture of the spleen.

CMV infections occur most commonly between ages 10 and 35 and by age 40, about half of adults have had CMV whether they know it or not. Blood tests are used to show who has developed antibodies against the virus.

In adults and children, CMV may produce a mononucleosis-like syndrome that resolves over a few weeks. In persons with weaker-than-normal immunity, such as those undergoing chemotherapy, those with HIV, or those receiving immunosuppressive drugs, CMV may cause pneumonia, colitis, and retinitis.

Most newborns with congenital CMV have no immediate symptoms but about ten percent may show small size, abnormalities in their livers and spleens, small heads, jaundice, purple skin rashes, or seizures. What makes CMV a serious health issue for newborns is that about 20% of children who are born with CMV, whether it is asymptomatic or symptomatic at birth, develop permanent health problems within the first few years of life. These include hearing and vision loss, low IQ, poor coordination, developmental delay, and seizures.

Hearing loss is the most common manifestation of CMV. It can occur at birth or later on, and can worsen over time. About 21% of hearing loss detected at birth is attributable to CMV, as is 25% of hearing loss detected at age 4 years. Fifty percent of children with hearing loss following congenital CMV infection will continue to have progression of their disability. Universal hearing screening is recommended for newborns and all children with congenital CMV infections should have close surveillance of their hearing to identify new and ongoing hearing loss.

How Mothers-to-Be Can Avoid CMV

The most common way for pregnant women to catch CMV is from getting bodily fluids of young children in their eyes, nose or mouth.

Women who are pregnant or planning to become pregnant are advised by the Centers for Disease Control (CDC) to avoid contact with urine or saliva of young children by washing hands often, especially after feeding, diapering, or washing a young child, avoiding sharing food drinks and utensils with young children and cleaning household surfaces with sanitizing cleansers.

Pregnant women are not routinely tested for CMV because a test of the mother will not predict whether or not the baby will be infected or whether it will suffer consequences of CMV infection. If a newborn is suspected of having congenital CMV, the mother's blood, urine, or saliva can be tested after birth to determine whether CMV is in fact present.

Treatment Options are Limited

The current medications available for CMV are considered too dangerous for routine use in infants although there are circumstances when the infant's symptoms are severe enough that the risk /benefit ratio is favorable for their use. Similarly, adults with compromised immune systems who become infected may warrant antiviral therapy depending on the clinical circumstances. There is currently no vaccine to prevent CMV.

The transmission of CMV by blood transfusions has been eliminated by the use of CMV negative donors and by treating the red and white cells before use. Transmission through donated breast milk can be reduced by pasteurization or freezing of the milk. If fresh milk is needed, using milk from CMV antibody-negative women is recommended. Transmission of CMV through sexual contact can be decreased by condom use.

In the United States, 1 in 750 children have disabilities, which are due to congenital CMV infection, and hearing loss is a major result of this infection. The CDC hopes that heightened awareness of this virus can help pregnant woman take measures to decrease their risk and the risk to their infant.



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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.