Cytomegalovirus Infection
A common virus that is usually harmless but can affect newborns and weakened immune systems
Quick Facts
- Type: Viral infection (herpesvirus family)
- How common: Very common worldwide
- Usually: Causes no symptoms in healthy people
- Higher risk: Newborns and weakened immune systems
Overview
Cytomegalovirus, or CMV, is a very common virus that belongs to the herpesvirus family. Many people are infected at some point in their lives, often during childhood, and most never know it because it usually causes no symptoms in healthy individuals.
Once a person is infected, the virus stays in the body for life in a dormant state and can reactivate, especially if the immune system weakens. While CMV is harmless for most people, it can cause serious illness in two main groups: babies infected before birth (congenital CMV) and people with weakened immune systems, such as those who have had an organ transplant or have advanced HIV.
Symptoms
Most healthy people have no symptoms. When symptoms do occur, they vary by group.
In otherwise healthy people:
- Fatigue and general malaise
- Fever
- Sore throat and swollen glands
- Muscle aches (a mononucleosis-like illness)
In babies with congenital CMV: Some have no symptoms, while others may have low birth weight, jaundice, an enlarged liver or spleen, a small head, or hearing loss that can appear or worsen over time.
In people with weakened immune systems: CMV can affect the eyes, lungs, digestive tract, or other organs, causing more serious illness.
Causes
CMV infection is caused by the cytomegalovirus, which spreads through close contact with body fluids of an infected person. The virus can be present in saliva, urine, blood, tears, semen, and breast milk. Common routes of spread include:
- Close personal contact: Such as caring for young children, who often shed the virus.
- From pregnant person to baby: Across the placenta during pregnancy.
- Through breast milk: To a nursing infant.
- Through transplanted organs or blood transfusions: In some cases.
- Sexual contact.
Once infected, the virus remains dormant and can reactivate later, particularly when the immune system is weakened.
Risk Factors
- Close contact with young children, who commonly carry the virus
- Working in childcare or healthcare settings
- Pregnancy, due to the risk of passing CMV to the baby
- Having a weakened immune system from organ or stem cell transplant, certain treatments, or advanced HIV
- Receiving blood transfusions or transplanted organs
Diagnosis
CMV is diagnosed with laboratory tests, used mainly when infection could be significant, such as in pregnancy, newborns, or people with weakened immunity.
- Blood tests: To detect antibodies showing past or recent infection, or to measure the virus directly.
- Newborn testing: Saliva or urine tests soon after birth to detect congenital CMV.
- Tissue or fluid tests: In people with weakened immunity, to check whether CMV is affecting specific organs.
- Hearing and eye evaluations: For babies with congenital CMV.
Treatment
Healthy people with no symptoms or a mild illness usually need no specific treatment and recover with rest and fluids. Antiviral medicines are reserved for those at higher risk.
- Supportive care: Rest, fluids, and fever relief for mild illness in healthy people.
- Antiviral medications: Used for serious CMV disease in people with weakened immune systems and for some newborns with symptomatic congenital CMV.
- Specialist follow-up: For affected babies, including ongoing hearing monitoring, since hearing loss can develop over time.
- Adjusting immune-suppressing treatment: When possible, in people whose treatment has lowered their immunity.
Prevention
- Wash hands often, especially after contact with young children's saliva, diapers, or toys
- Avoid sharing food, drinks, and utensils with young children
- Avoid contact with the saliva of young children when kissing them, particularly during pregnancy
- Practice safe sex to reduce transmission
- People with weakened immune systems should follow their care team's specific advice
There is currently no vaccine for CMV, so hygiene is the main way to reduce spread, especially during pregnancy.
When to See a Doctor
See a doctor if you are pregnant and think you may have been exposed to CMV or have a mononucleosis-like illness, so testing and monitoring can be arranged.
People with weakened immune systems should seek prompt care for fever, vision changes, shortness of breath, severe diarrhea, or other new symptoms, as CMV can cause serious organ disease in this group. Parents should follow up on recommended hearing tests for a baby diagnosed with congenital CMV, since hearing loss may appear or progress over time.
Frequently Asked Questions
Is CMV dangerous?
For most healthy people, CMV is harmless and often causes no symptoms. It can be serious for babies infected before birth and for people with weakened immune systems, such as transplant recipients or those with advanced HIV, who may develop organ disease.
How does CMV spread?
CMV spreads through close contact with body fluids such as saliva, urine, blood, and breast milk. Young children often carry and shed the virus, so caring for them is a common way adults get infected. It can also pass during pregnancy and through transfusions or transplants.
Why is CMV a concern in pregnancy?
A pregnant person can pass CMV to their baby, which can cause congenital CMV. This may lead to hearing loss or other problems, sometimes appearing after birth. Good hand hygiene and avoiding contact with young children's saliva help reduce the risk during pregnancy.
Is there a cure for CMV?
There is no cure that removes the virus, which stays dormant for life after infection. Antiviral medicines can control serious CMV disease in high-risk people and some affected newborns, but healthy people with mild illness usually need only supportive care.
Can CMV cause hearing loss in babies?
Yes. Congenital CMV is a leading non-genetic cause of hearing loss in children. The loss may be present at birth or develop later, which is why affected babies need ongoing hearing monitoring.
References
- Centers for Disease Control and Prevention (CDC). Cytomegalovirus (CMV).
- Mayo Clinic. Cytomegalovirus (CMV) infection — Symptoms and causes.
- MedlinePlus, U.S. National Library of Medicine. Cytomegalovirus (CMV) infection.
- National Institute on Deafness and Other Communication Disorders (NIDCD).