Causes of cytomegalovirus (CMV)

Infection with cytomegalovirus (CMV) is mainly caused by close physical contact.

CMV is a common virusthat is related tothe viruses that cause Herpes zoster virus and glandular fever .

HowCMV is spread

CMV is primarily spread through bodily fluids, including:

  • saliva
  • semen
  • blood
  • urine
  • vaginal fluids
  • breast milk

You can become infectedby touching surfaces that are contaminated with saliva or urine, and then touching the inside of your nose or mouth. CMV can also be spread during kissing or sexual intercourse.

Most CMV infections occur in early childhood. The infection can spread rapidly in places where young children spend time in close contact with each other, such as day care centres and nurseries.

By the time a child is old enough to attend, their immune system should be strong enough to deal with an infection.However, they can take CMV home to their mother, who may be pregnant.

If you experience symptoms of a CMV infection , they should pass quickly. If you're healthy, the virus will lie dormant (inactive) in your body's cells for the rest of your life.

Active CMV

CMV can be a problem for people who have a severely weakened immune system, leading to the virus infecting the body's organs.

Your immune system may become weakened if you:

  • have HIV that's not currently being treated
  • have been taking oral steroid tablets for more than three months, or other types of high-dose steroids or immunosuppressants
  • are taking medication needed for a transplant

Active CMV frequently occurs after a person hashad an organ transplant or a bone marrow transplant .

CMV and breastfeeding

CMV can be passed from a mother to her child through breast milk. However, the benefits of breastfeeding your baby far outweigh any risk from CMV.

The one exception is if a child is born prematurely. The immune system of premature babies is often not strong enough to deal with a CMV infection. Your treatment team will advise youon the best way to feed your premature baby.

Congenital CMV

Congenital CMV is where a mother passes a CMV infection on to her unborn baby.

Some cases occur when a pregnant woman is infected by CMV for the first time during, or shortly before, pregnancy (a primary infection). In around 3 out of 10 cases, the baby will also be infected.

In some cases, a previously inactive CMV infection can recur during pregnancy. The mother could also be reinfected with another strain of the CMV virus, whichcan be passed to her unborn baby.

In the majority of cases, the virus doesn't harm the baby. However, in severe cases, it caninterfere with the babys normal development, resulting in the associated disabilities and symptoms of congenital CMV .

Content supplied by the NHS Website

Medically Reviewed by a doctor on 22 Aug 2016