The Epstein-Barr virus (EBV) is a member of the herpes virus family, and it is one of the most common viruses to infect humans around the world. The Centers for Disease Control and Prevention report that as many as 95 percent of U.S. adults between ages 35 and 40 have been infected with EBV at some point in their lives (CDC).
In children, the virus typically causes no symptoms. In adolescents and adults, it causes an illness known as infectious mononucleosis between 35 and 50 percent of the time. The virus is spread through saliva or upper respiratory secretions and cannot be spread through contact with the blood.
The Epstein-Barr virus test is a blood test used to identify an EBV infection. The test detects the presence of antibodies, which are proteins that your body’s immune system releases in response to a harmful substance, called an antigen. Specifically, the EBV test is used to detect antibodies to EBV antigens. The test can detect both a current infection and one that occurred in the past.
Your doctor may order this test if you show any of the signs and symptoms of infectious mononucleosis. Symptoms typically last for one to four weeks and include:
- sore throat
- swollen lymph glands
- stiff neck
Your doctor may also take into account your age and other factors when deciding whether or not to order the test. Mononucleosis is most common in teens aged 15 to 17 because it spreads most easily through contact with saliva. For this reason, it is sometimes called the “kissing disease.”
The EBV test is a blood test performed by a nurse at your doctor’s office or an outpatient clinical laboratory. Blood is drawn from a vein, usually on the inside of your elbow. The blood draw involves the following steps:
- The puncture site is cleaned with an antiseptic.
- A nurse wraps an elastic band around your upper arm to make your vein swell with blood.
- A needle is gently inserted into the vein to collect blood in an attached vial or tube.
- The elastic band is removed from your arm.
- The blood sample is sent to a lab for analysis.
Very little (or even no) antibody may be detected early in the illness. So, the blood test may need to be repeated in 10 to 14 days.
As with any blood test, there is a slight risk of bleeding, bruising, or infection at the puncture site. You may feel moderate pain or a sharp prick when the needle is inserted. Some patients feel light-headed or faint after having blood drawn.
A normal result means that no EBV antibodies were present in your blood sample. This indicates that you have never been infected with the Epstein-Barr virus and do not have infectious mononucleosis. However, you are still susceptible to infection in the future.
An abnormal result means that the test has detected EBV antibodies. This means that you are currently infected with EBV or have been infected with the virus in the past. Your doctor can tell the difference between a past and a current infection based on the presence or absence of antibodies that fight three specific antigens.
The three antibodies the test looks for are viral capsid antigen (VCA) IgG, VCA IgM, and Epstein-Barr nuclear antigen (EBNA).
- The presence of VCA IgG antibodies indicates that an EBV infection has occurred at some time (recently or in the past).
- The presence of VCA IgM antibodies and the absence of antibodies to EBNA means that the infection has occurred recently.
- The presence of antibodies to EBNA means that that infection occurred sometime in the past. Antibodies to EBNA develop six to eight weeks after primary infection and are present for life.
As with any test, false positive and false negative results do occur. The CDC found that false negative results occur in 10 to 15 percent of patients. However, false negatives occur primarily in tests of children younger than 10 (CDC).
There is no known treatment for infectious mononucleosis and no antiviral drugs or vaccines are available. Symptoms usually resolve on their own in one or two months.
However, EBV will remain dormant in your blood cells for the rest of your life and can occasionally reactivate without symptoms. It is possible to spread the virus to others through mouth-to-mouth contact during this time.