Monotest, Paul-Bunnell test, Epstein-Barr (for mononucleosis)
Mononucleosis is an infectious disease caused by a virus belonging to the herpesvirus family and is common especially in young people. The infection causes general malaise and is not particularly dangerous, but in some cases it can become more serious, especially if the virus affects an adult. This is why early diagnosis is important, and it is made with three types of test:
- The Monotest
- The Paul-Bunnell test
- IgG and IgM antibodies against Epstein-Barr virus
Why they are done
Mononucleosis is difficult for the doctor to diagnose because the signs are not always clear and obvious, especially in young children (the disease can look like simple flu). These tests confirm it. However, they are generally not requested on their own but together with the full blood count, for examination of the white blood cells under the microscope (which in this disease appear “very large” and are called “virocytes” or “activated lymphocytes”), and the transaminases (which may be high in mononucleosis, although only temporarily).
How they are done
These laboratory tests involve a normal blood sample and require no specific preparation other than fasting. Taking medicines does not affect the result, but it is always important to tell your doctor what products you are taking, especially if the results are abnormal, so that they can take your overall state of health into account.
Results
Monotest: the mononucleosis virus is not present in the blood if the test is “negative” or “absent”, while it is present if the test is “positive” or “present”. However, this test is not precise, so even if the result is “negative” it is always advisable to investigate further by testing for specific Epstein-Barr antibodies. If, on the other hand, the result is “positive”, the Paul-Bunnell test is generally carried out for confirmation.
Paul-Bunnell test: the mononucleosis virus is not present in the blood if the test is “negative” or “absent”, while it is present if the test is “positive” or “present”. This test generally indicates that the disease is in the acute phase.
IgG and IgM antibodies against Epstein-Barr virus: testing for IgG and IgM antibodies can give several results:
If both IgG and IgM antibodies are “negative”, you have not had mononucleosis. If, despite this, the full blood count shows the “activated lymphocytes” typical of this infection, it may actually be cytomegalovirus, a virus that is not particularly dangerous unless caught during pregnancy (because of the harm it could cause to the baby).
If both IgG and IgM antibodies are “positive” or “present”, mononucleosis is under way and in the acute phase. In this case the Monotest and the Paul-Bunnell test are generally “positive” too.
If IgG antibodies are “negative” while IgM antibodies are “positive”, the disease is in the acute phase, probably in the first to third week of illness. In this case too, the Monotest and the Paul-Bunnell test should be “positive”.
• If IgG antibodies are “positive” and IgM antibodies are “negative”,
the person is recovering from the disease and has passed the acute phase. This pattern persists for a very long
time after the illness, because IgG antibodies remain over time while IgM antibodies disappear with recovery.