Most people infected with CMV who are otherwise healthy experience few if any signs and symptoms. People at greater risk of signs and symptoms of CMV include:

• Newborns infected with CMV before birth (congenital CMV).
• Infants who become infected during birth or shortly afterward (perinatal CMV). This group includes babies infected through breast milk.
• People with weakened immune systems, for example due to organ transplant or HIV infection.

Babies

Most babies with congenital CMV appear healthy at birth.

A few babies with congenital CMV who appear healthy at birth can develop signs over time — sometimes not for months or years after birth. The most common of these late-occurring signs are hearing loss and developmental delay. A small number of babies may also develop vision problems.

Babies with congenital CMV who are sick at birth tend to have significant signs and symptoms, including:

• Premature birth
• Low birth weight
• Yellow skin and eyes (jaundice)
• Enlarged and poorly functioning liver
• Purple skin splotches or a rash or both
• Abnormally small head (microencephaly)
• Enlarged spleen
• Pneumonia
• Seizures

People with weakened immunity

If your immune system is weakened, you might experience more-serious signs and symptoms affecting your:

• Eyes
• Lungs
• Liver
• Esophagus
• Stomach
• Intestines
• Brain

Otherwise healthy adults

Most people infected with CMV who are otherwise healthy experience few if any signs or symptoms. When first infected, some adults may have symptoms similar to infectious mononucleosis, including:

• Fatigue
• Fever
• Sore throat
• Muscle aches

CMV mononucleosis is less likely than infectious mononucleosis to cause enlarged lymph nodes and spleen.

CMV is related to the viruses that cause chickenpox, herpes simplex and mononucleosis. CMV may cycle through periods when it lies dormant and then reactivates. If you're healthy, CMV mainly stays dormant.

During activation you can pass the virus to other people. Casual contact doesn't transmit CMV. The virus is spread through body fluids — including blood, urine, saliva, breast milk, tears, semen and vaginal fluids.

Transmission might occur through:

• Touching your eyes or the inside of your nose or mouth after coming into contact with the body fluids of an infected person.
• Sexual contact with an infected person.
• The breast milk of an infected mother.
• Organ transplantation or blood transfusions.
• Birth. An infected mother can pass the virus to her baby before or during birth. The risk of virus transmission to your baby is higher if it's the first time you've had the infection rather than a reactivated infection.

CMV is a widespread and common virus that can infect almost anyone. Most healthy children and adults who contract the virus have few if any symptoms, so CMV often goes undiagnosed.

Complications of CMV infection vary, depending on your overall health and when you were infected.

Otherwise healthy adults

Rarely, CMV causes a healthy adult to develop mononucleosis. Other rare complications for healthy adults include problems with the digestive system, liver, brain and nervous system.

People with weakened immunity

Complications of CMV infection can include:

• Vision loss, due to inflammation of the light-sensing layer of the eye (retinitis)
• Digestive system problems, including inflammation of the colon (colitis), esophagus (esophagitis) and liver (hepatitis)
• Nervous system problems, including brain inflammation (encephalitis)
• Pneumonia

Infants with congenital CMV

Complications are more likely to develop if the infant's mother had a primary CMV infection during pregnancy, rather than a reactivated infection. Complications for the baby can include:

• Hearing loss
• Intellectual disability
• Vision problems
• Seizures
• Lack of coordination
• Weakness or problems using muscles