CMV

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Formal name: Cytomegalovirus Antibody, IgG and IgM; Cytomegalovirus by PCR

At a Glance

Why Get Tested?

If your doctor suspects you presently have, or recently had, a cytomegalovirus (CMV) infection OR if it is important to know if you have ever had a CMV infection – such as prior to receiving an organ transplant.

When to Get Tested?

When a young adult, a pregnant woman, or an immune-compromised person has flu-like symptoms that suggest a CMV infection; prior to receiving an organ transplant; when a newborn has multiple congenital abnormalities, unexplained jaundice or anaemia, and/or when an infant has seizures, hearing loss or developmental problems that may be due to CMV.

Sample Required?

A blood sample drawn from a vein in your arm for CMV antibody testing; to detect the virus itself. Alternatively the sample may be blood, urine, sputumamniotic fluid, cerebrospinal fluidduodenal fluid, or other body tissue.

Test Preparation Needed?

None

The Test Sample

What is being tested?

Cytomegalovirus (CMV) is a common virus that occurs widely throughout the population but rarely causes symptoms. In Australia, by the age of 20 years, around 50% of adults have been infected with CMV and this proportion increases with age. Most people are infected as children or as young adults and do not experience any significant symptoms or health problems.

CMV is found in many body fluids during an active infection, including saliva, urine, blood, breast milk, semen, vaginal secretions, and cerebrospinal fluid. It is easily transmitted to others through close physical contact or by contact with infected objects, such as diapers or toys. After the initial "primary" infection has resolved, CMV becomes dormant or latent - like other members of the herpes virus family. Cytomegalovirus remains in a person for the rest of his life without causing any symptoms, unless the person's immune system is significantly weakened. If this happens, the virus can reactivate.

CMV can cause notable health problems in three situations:

  • In young adults, primary CMV infection may cause a flu-like or glandular fever-like illness. This condition, which causes symptoms such as extreme fatigue, fever, chills, body aches and/or headaches, usually resolves within a few weeks. 
  • In infants and children, CMV infection acquired antenatally (during pregnancy) may cause serious physical and developmental problems. This occurs most commonly when women are infected for the first time (primary infection) during pregnancy and then pass the infection to the developing baby across the placenta. Most newborns (around 90%) that are infected appear healthy at birth and most remain well, but a small proportion may develop hearing problems or delayed mental development later. A few babies may be stillborn, while others may have symptoms at birth such as jaundiceanaemia, an enlarged spleen or liver, and a small head.
  • In those with weakened immune systems, CMV can cause serious illness and death. This includes those with HIV/AIDS, those who have had organ or bone marrow transplants and those undergoing chemotherapy treatment for cancer. People with compromised immune systems who become infected for the first time (primary infection) might experience the most severe symptoms, and their CMV infection may remain active. Those who have been exposed to CMV previously may reactivate their infection. This could affect their eyes (causing inflammation of the retina, which can lead to blindness), digestive tract (causing bloody diarrhoea and abdominal pain), lungs (causing pneumonia with a cough and shortness of breath), and brain (causing encephalitis). There can also be spleen and liver involvement, and those who have had organ or bone marrow transplants may experience some degree of rejection. Active CMV also further depresses the immune system, potentially allowing other secondary infections, such as fungal infections, to occur.

CMV testing involves either a measurement of CMV antibodies, immune proteins created in response to CMV exposure, or by the detection of the virus itself. The virus can be identified during an active infection by culturing CMV or more commonly, by detecting the virus's genetic material (its DNA) in a fluid or tissue sample with a process known as polymerase chain reaction testing or PCR.

How is the sample collected for testing?

The sample required depends on the type of testing. Antibody testing requires a blood sample, obtained by inserting a needle into a vein in the arm. Viral detection (usually by PCR) may be done on a variety of samples, including urine, blood, saliva or sputum. Some samples may require a special procedure to collect, such as amniotic fluidduodenal fluid, cerebrospinal fluid, or body tissue (biopsy).

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

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