Cytomegalovirus (CMV) is a common virus. According to the Centers for Disease Control and Prevention (CDC), it infects between 50 to 80 percent of all adults (CDC, 2010). Usually, CMV does not cause any symptoms or health problems. It will remain in your body in a latent form. This means that the virus is present but not causing any symptoms. If you develop health problems that weaken your immune system, CMV may become active. It can then become an acute infection.
The CMV serology test detects antibodies to CMV. You will have elevated CMV antibody levels if you have been infected with CMV.
CMV tests are usually ordered for adults with compromised immune systems and pregnant women who have symptoms such as:
- sore throat
- swelling in the lymph nodes
- muscle aches
The flu, mononucleosis (mono), or Epstein - Barr virus (EBV) could also cause these symptoms.
The CMV test may be ordered for a newborn with the following symptoms:
- yellowing of the skin or eyes (jaundice)
- enlarged spleen or liver
- hearing or vision problems
- delayed development
CMV serology can be used to determine if treatment for an active CMV infection is working. The test is also used as a screening tool for:
- those seeking an organ transplant
- organ donors
- egg and sperm donors
The CMV serology test is performed on a blood sample. A nurse or lab technician in a clinical setting usually takes this sample. Using a small needle, blood is collected from a vein in the arm or hand. The blood is then sent to a lab for analysis. Your doctor will explain your results when they become available.
No preparation is needed for this test.
The risks of a CMV test are minimal. You may experience some discomfort when the blood sample is drawn. You may have pain at the puncture site during or after the test.
Other potential risks of a blood draw include:
- difficulty obtaining a sample, resulting in multiple needle sticks
- excessive bleeding at the needle site
- fainting as a result of blood loss
- accumulation of blood under the skin, known as a hematoma
- infection at the puncture site
A negative test means there are no CMV antibodies in your blood. This suggests that you have never been infected with CMV. It may also indicate that you are immunocompromised and your immune system can’t make antibodies against the virus.
Low levels of CMV antibodies indicate exposure to CMV. However, they do not reveal when you were infected. Your doctor will need to review your results in conjunction with your symptoms to determine if you have an active infection.
When the test is used to monitor treatment efficacy, your doctor will look for a decline in the amount of CMV antibodies over time. As treatment lowers viral levels, antibody levels should decline as well.