Cytomegalovirus (CMV) is a common virus that usually causes no symptoms or only mild illness. CMV testing detects antibodies in the blood that the body produces in response to the infection or detects CMV directly.
In the United States, as many as 60% of people have been exposed to CMV at some point in their life. Almost 1 out of every 3 children have been exposed to CMV by age 5 and more than half of adults are exposed to CMV by age 40.
Most people are infected as children or as young adults, but many don't know it because CMV usually does not cause noticeable symptoms or only mild illness in otherwise healthy people. Individuals with mild illness may have non-specific signs and symptoms, such as sore throat, fever, tiredness, and swollen glands. In otherwise healthy adults, CMV infection may sometimes cause a flu-like illness or signs and symptoms similar to mononucleosis (mono), such as extreme fatigue, fever, chills, body aches, and/or headaches that usually resolve within a few weeks.
CMV is found in many body fluids during an active infection, including saliva, urine, blood, breast milk, semen, vaginal fluid, and cerebrospinal fluid. CMV easily spreads from person to person through close contact with someone who is infected or by contact with contaminated body fluids or objects, such as diapers or toys.
Once you are infected, CMV remains in your body for the rest of your life without causing symptoms. After your initial "primary" infection resolves, CMV becomes dormant or latent, like other members of the herpes family. However, if your immune system is significantly weakened, the virus can become active again (reactivate) and cause illness.
CMV can cause notable health problems in these situations:
- A pregnant woman who is infected for the first time (primary infection) during pregnancy can pass the infection to her developing baby across the placenta. This can cause serious physical and developmental problems in the baby. Most newborns (about 90%) who are infected appear healthy at birth but may develop hearing or vision problems, pneumonia, seizures, and/or delayed mental development a few months later. A few babies may be stillborn, while others may have symptoms at birth such as jaundice, anemia, an enlarged spleen or liver, and a small head.
- CMV can cause serious illness and death in people with weakened immune systems, such as those with HIV/AIDS, solid organ or bone marrow transplant recipients, and cancer patients receiving chemotherapy. These individuals might experience the most severe symptoms and their CMV infection may remain active. CMV may reactivate in those who were previously exposed. The infection could affect the:
- Eyes, causing inflammation of the retina, which can lead to blindness
- Digestive tract, causing bloody diarrhea and abdominal pain
- Lungs, causing pneumonia with a non-productive cough and shortness of breath
- Brain, causing encephalitis
- Spleen and liver
- Organ or bone marrow transplants, causing some degree of rejection
- Active CMV also further depresses the immune system, allowing other secondary infections such as fungal infections, to occur.
The following table summarizes possible antibody testing results:
| CMV, IgM | CMV, IgG | Possible Interpretation |
| Negative | Negative |
|
| Positive | Negative |
*Result is NOT diagnostic of primary infection |
| Positive | Positive (with four fold increase in titer between first sample and another collected later (acute and convalescent samples) | Likely active primary or reactivated latent infection |
| Negative | Positive | Past exposure (immunity to primary infection); latent infection |
Cytomegalovirus Antibody (IGG)
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