Cytomegalovirus Antibody (CMV) Test - IgM

CMV (Cytomegalovirus) is a common virus. It belongs to the herpes family. CMV is an infection that is widespread in many areas, but the symptoms are not severe. In most people, a mild illness develops with almost no symptoms. Some may experience mild symptoms such as sore throat, mild fever, tiredness, swollen glands, malaise, etc.

Serological testing is widely used in the diagnosis of CMV. This type of test is called a Multiplex Flow Immunoassay (MFI). The type of specimen required for the test is the patient’s serum (serum is the liquid component of blood after all cells like RBC, WBCs, platelets are removed). This test detects the presence of CMV antibody in the patient’s serum and is then used for the diagnosis of a CMV infection.

Antibodies are a natural immune response of the body to fight off infection. When the virus enters the body, antibodies are formed (IgM and IgG). The IgM antibodies are the first to appear in the sample. Their presence can be evaluated a week or two after the initial exposure to CMV through the CMV Antibody IgM test results.

The level of IgM antibodies declines after two weeks, after which they are not detectable in the blood. The range of IgG antibodies rises after the first two weeks.

CMV especially causes major health concerns in pregnant women and newborn infants. Women who contract the infection during their pregnancy have a high chance of passing it on to the foetus. The CMV Antibody IgM test helps in preventing congenital CMV in the newborn baby.

CMV is also a major cause for concern for immunocompromised individuals. This may include people who have undergone bone marrow transplants or organ transplants, etc.

Thus, it may prove to be fatal for people with weakened immune systems.

Doctors recommend this type of testing as it is one of the most accurate methods and provides fast and satisfactory results of either positive or negative very clearly.

CMV spreads through blood, urine, saliva, semen, breast milk, etc. It is particularly prominent in certain parts of the United States, where most people acquire the infection by the time they turn 40 years of age. Most people retain the virus in their bodies and do not even show any symptoms.

In India, the prevalence of this disease is up to 80-90%. This means that this amount of the adult population in India has the antibodies for the virus.

Chickenpox, Herpes simplex, Mononucleosis

CMV Antibody IgM test measures the levels of IgM antibodies in the serum of individuals who have been infected with CMV.

Further, CMV antibody IgM is used in the diagnosis of:

• People who have a current CMV infection or those who have had it in the past but are at risk of re-infection or developing the disease again.
• Newborns where there is reason to believe there would be a congenital disease when a baby shows certain typical signs such as jaundice or spleen or liver enlargement, etc. or if it shows developmental abnormalities.
• Healthcare practitioners who have been monitoring a patient closely.
• A person who has had a bone marrow or organ transplant.

It is usually prescribed if one of the following conditions is suspected by the doctor:

• Chickenpox
• Herpes simplex
• Mononucleosis

This test may be asked when a person with weak immunity or a pregnant female shows flu-like symptoms.

These include:

• Fever
• Sore throat
• Malaise
• Fatigue
• Swollen lymph nodes

• The CMV Antibody IgM test is prescribed if there is a possibility of a recent or re-infection.
• You need to retake the CMV Antibody IgM test again in 2 weeks if there is a reason for the doctor to believe that there is a possibility of re-infection.
• This test is not a part of a regular health check-up.

Before the Test

Before undergoing the CMV Antibody Test, your doctor will likely not require any special precautions. However, if you need to take this test along with another that requires special preparation, your doctor may recommend fasting for a specific time. Always consult your doctor before undergoing any test to get advice.

During the Test

For the  CMV Antibody Test, a phlebotomist will draw a blood sample from a vein of your arm. Here's what will happen during the test:

• The likely puncture site will be sterilised with antiseptic.
• A tourniquet will be secured around your arm to make your veins stand out.
• A needle will be inserted into a chosen vein to draw the blood. This may cause a brief pinch for a few seconds.
• The blood will be collected in a vial/small test tube, and a label will be affixed with your details.

After the Test

Following the blood collection:

• A bandage will be applied to stop the bleeding at the insertion site.
• You may notice bruising at the puncture site. If you feel lightheaded, you should sit and rest for a few minutes.
• If you notice persistent bleeding, pain, or if rashes develop at the puncture site, contact your doctor.

This procedure is used to detect the presence of IgM antibodies in response to the Cytomegalovirus. When the virus enters the body, it produces an antibody response.

No other parameters are tested in this test.

The following chart displays the ranges or values of the CMV antibody IgM test:

Unit: IU/mL

The normal values and reference ranges of the test may vary from lab to lab. Please refer to the ranges mentioned in the report and consult a doctor to understand the interpretation of lab reports.

Typically, the CMV-IgM Antibody Test results are interpreted in conjunction with the results of the CMV-IgG antibody test.

• If both CMV-IgG and CMV-IgM are negative: it indicates no current or prior infection.
• If CMV-IgG is positive and CMV-IgM is negative: it indicates past exposure to the virus.
• If CMV-IgG is negative and CMV-IgM is positive: it indicates a recent infection that was active, or it may also indicate re-exposure to CMV or a latent stage of the disease.
• If both CMV-IgG and CMV-IgM are positive: it indicated active primary infection or re-infection that was latent but is now active again.