Cytomegalovirus (CMV) Infection

Cytomegalovirus (CMV) is an illness you get from a herpes virus (an organism that uses your cells to make more copies of itself). Many people will get infected in their lifetime, but most will have mild or no symptoms. CMV can cause serious complications in people living with a compromised immune system.

People who are pregnant can pass CMV to the fetus, which can cause congenital CMV. Congenital CMV is a condition that’s present at birth and can lead to hearing loss or developmental issues.

Who does cytomegalovirus affect?

While CMV can infect anyone, most people won’t have symptoms. CMV is most dangerous in pregnancy and for those with weakened immune systems, like people living with HIV or those who’ve had an organ or stem cell transplant.

CMV in pregnancy

If you get cytomegalovirus during pregnancy or shortly before getting pregnant, you can pass the virus through the placenta to the fetus. This increases the risk of pregnancy loss (miscarriage) and your child being born with health issues. Complications of being born with CMV include vision or hearing loss and developmental delays.

CMV when you have a compromised immune system

If you’re living with HIV or you’re taking immune-suppressing medications for an organ or stem cell transplant, your immune system can’t easily fight off infections like cytomegalovirus. This means you have a weakened immune system (immunocompromised).

If you’ve had CMV in the past, the virus can stay in your body, inactive. When your immune system is weakened, it can reactivate and cause you to get sick. While most people can fight off CMV without symptoms, a new or reactivated infection can cause serious complications in someone with a weakened immune system.

Who is at higher risk for CMV?

You’re at higher risk for cytomegalovirus if you:

• Are under the age of 5. About 33% of children have had a CMV infection by the age of 5.
• Work with or live with children under the age of 5.
• Have a compromised immune system. This includes those living with HIV/AIDS and people who’ve had a stem cell or organ transplant.
• Live in close contact with many other people (crowded conditions).

How common is CMV?

CMV is a common infection, but most people who are infected don’t have any symptoms. In the U.S. and Canada, experts estimate that:

• Half of all people will have had a cytomegalovirus infection by age 40.
• Up to 90% of all people will be infected by age 80.
• About 1 in 200 babies is born with CMV each year, though only 10% (1 in 10) will have symptoms at birth.