Cytomegalovirus Antibody (CMV) Test - IgG

Cytomegalovirus infection is caused by cytomegalovirus (CMV). It spreads when we come in direct contact with the saliva, blood, breast milk, semen or any body fluid of the infected person. It can also be spread by touching the objects and things of an infected person. It can be passed from mother to child during pregnancy.

The immune system of our body produces antibodies (CMV-IgG and CMV-IgM) against the cytomegalovirus. Some antibodies remain in the body even after recovering from the CMV infection. The CMV Antibody IgG Test detects these IgG antibodies in the blood. Once you get the infection (primary infection), the virus will remain in the body for life in an inactive form. As soon as the immunity of the body becomes weak, the virus reactivates and causes illness.

CMV infection can affect men and women of all ages. Usually, CMV infection does not cause any serious health issues. Most people don’t even know they have the infection. In some people, it can cause symptoms like that of common flu, extreme fatigue, fever, chills, headache and body pain. They usually resolve in a few days or weeks.

CMV infection can cause serious health problems in pregnant women. It can spread to the baby and can cause vision or hearing problems, pneumonia, jaundice, anaemia and delay the mental development of the newborn. Sometimes, it can cause the death of a baby before or during the delivery (stillbirth).

CMV infection can cause serious health issues in people with weak immune systems. Those who have HIV/AIDS infection, going for organ transplant and having chemotherapy for cancer treatment. They have a weak immune response. CMV can affect their eyes, lungs, brain, liver or spleen. It can also lead to other infections as it further suppresses the immunity of the body.

The CMV antibody test is prescribed in pregnancy, blood transfusion cases, organ transplant cases and in cancer therapy to avoid any complications. The number of CMV infections is high in both developed and developing countries. In India, it has been reported that 80-90% of the adult population has CMV. The infection is more common in pregnant women. It is a major public health issue. CMV requires health policies to prevent its spread. Currently, there is no vaccine available for CMV.

Cytomegalovirus Infection, Recurrent CMV infection

The CMV Antibody IgG Test detects the IgG antibodies developed by the immune system of our body in response to CMV infection.

The CMV antibody IgG test results will help with the diagnosis of CMV infection. If the infection is present, antiviral medicines are prescribed by the consulting physician. In pregnant women, a CMV IgG avidity test is also done to identify primary CMV infection. The test is used across the globe and is considered a gold standard for primary CMV infection.

The CMV antibody test is also part of the TORCH screening. TORCH means toxoplasmosis, rubella, cytomegalovirus, herpes simplex and HIV infection. The TORCH screen result will show the presence or absence of antibodies IgG or IgM against one or more of the above-mentioned infections. The CMV antibody IgG test is suitable for both genders of age above 12 months.

If a person is experiencing symptoms like:

• High fever
• Loss of appetite
• Headache
• Muscle pain
• Fatigue
• Body pain
• Sore throat
• Swelling in lymph nodes

The CMV Antibody IgG Test is prescribed by the consulting physician. CMV testings may also be prescribed to a newborn child if it has:

• CMV-infected mother
• Yellow eyes and skin (Jaundice)
• Low count of platelet
• Pneumonia
• Enlarged liver or spleen
• Hearing problem
• Vision problem
• Small head
• Seizures
• Delay in the mental development of the baby

The consulting doctor may prescribe the CMV antibody IgG Test in the following conditions:

• During pregnancy
• HIV/AIDS infection
• Organ transplantation (both donor or receiver)
• Bone marrow transplantation (both donor and receiver)
• Cancer
• Chemotherapy

A CMV Antibody test is used to diagnose past or current CMV infection by detecting the IgG and IgM antibodies against it. It is not tested on everyone. It is mainly prescribed to an immunocompromised person with symptoms like that of common flu, pregnant women and people undergoing organ transplant surgery. The doctor may ask you to repeat the test after two weeks or more to check the status of infection and CMV antibodies.

Before the Test

Before undergoing the CMV antibody IgG 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 IgG 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.

The parameters of the CMV Antibody IgG Test includes:

• Presence of CMV antibody IgG
• Amount of CMV antibody IgG

The test is applicable for a person with an age equal to or more than 12 months (at this age, antibodies from the mother disappear). The results of the CMV Antibody IgG Test are expressed as CMV IgG positive and CMV IgG negative. If CMV antibodies are found in the blood sample, it is considered CMV IgG positive. If CMV antibodies are not found in the blood sample, it is considered CMV IgG negative.

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.

The interpretation of the CMV IgG Test result will be:

• Negative: If the level of CMV IgG antibodies is less than 0.8 AI which means the person is not infected by CMV, recently or in the past.
• Positive: If the level of CMV IgG antibodies is more than 1.1 AI it means the person is infected with CMV infection, recently or in the past.
• Equivocal: If the level of CMV IgG antibodies is 0.9 to 1.1AI. The test is repeated after 10-14 days.

The diagnosis of CMV infection will depend upon the presence and absence of both CMV IgG and CMV IgM antibodies in the blood. They will help in identifying whether it is a recent infection or a past infection.

The CMV IgM is produced as the first response of our body to CMV infection. They can be detected within 1 or 2 weeks after the infection. After that, the antibodies will decrease and fall below the detectable level. Once the inactive virus reactivates in the body, the CMV IgM antibody level will increase again.

The CMV IgG antibodies are produced several weeks after the CMV infection. Initially, they rise, but later they become stable. Once you get infected with CMV infection, the CMV IgG antibodies will remain at a detectable level in the blood for a lifetime.

The CMV infection will be interpreted by the CMV antibody test results as:

• Negative CMV IgG + Negative CMV IgM- No CMV infection recent or in the past
• Negative CMV IgG + Positive CMV IgM- Recent primary CMV infection
• Positive CMV IgG + Negative CMV IgM- CMV infection in the past
• Positive CMV IgG + Positive CMV IgM- Recurrence of CMV infection or Active CMV infection