Transmission

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The risk of getting cytomegalovirus (CMV) through casual contact is very small. The virus is generally passed from infected people to others through direct contact with body fluids, such as urine, saliva, or breast milk. CMV is sexually transmitted. It can also be spread through transplanted organs and blood transfusions.

People who are infected with CMV can shed the virus (pass the virus from their infected body fluids, such as urine, saliva, blood, and semen, into the environment). Young children often shed CMV for months after they first become infected. Although parents of children who are shedding the virus can become infected from their children, CMV does not spread easily. Less than 1 in 5 parents of children who are shedding CMV become infected over the course of a year.

Although CMV can be shed in breast milk, infections that occur from breastfeeding usually do not cause symptoms or disease in the infant and there are no recommendations against breast feeding. Because CMV infection after birth may cause disease in very premature or low birth weight infants, mothers of these infants should consult their healthcare providers about breastfeeding.

CMV Transmission during Pregnancy

In the United States, approximately 30-50% of women have never been infected with CMV. About 1-4 of every 100 women who have never been infected with CMV have a primary (first) CMV infection during pregnancy. About one third of women (33 of every 100) who become infected with CMV for the first time during a pregnancy will pass the infection to their infant.

In the United States, approximately 50-80% of women have been infected with CMV by the age of 40 years. If a woman is infected with CMV before becoming pregnant, the risk of passing the virus to her fetus is about 1 in 100.

For pregnant women, the two most common exposures to CMV are through sexual contact and through contact with the urine and saliva of young children with CMV infection.

If you have concerns about CMV infection and are pregnant or planning a pregnancy, talk with your healthcare provider.

No actions can eliminate all risks of catching CMV from young children, but there are some measures that may reduce its spread (for details, see Prevention).The main goal of these measures is to avoid getting children's urine and saliva on your hands or in your eyes, nose, or mouth.

CMV Transmission to Infants before Birth

CMV can be transmitted from a pregnant woman to her fetus during pregnancy. The virus in the mother’s blood crosses over the placenta and infects the fetus’ blood.

Among infants born with CMV infection (congenital CMV infection), about 1 in 5 will have permanent disabilities, such as developmental disabilities or hearing loss.

 

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