Exams and Testing for Infectious Mononucleosis

Mononucleosis, or mono as it is usually referred to, is a viral infection which is contracted in a variety of ways - not the least of which is through saliva - hence the moniker, "the kissing disease". Truth be told, most adults have been in contact with the virus and don't even know it. The root cause of mono is the Epstein-Barr virus (EPV) and when a person suspects mono, they are tested for the presence of this virus in their blood. Once a person has contracted EPV, it remains in their body for life.

Diagnosing Mono

Mono can appear in babies and adults, although we most often associate its presence with teens and college-age people. It often goes unnoticed or is passed off as a flu virus or bad cold. Symptoms usually last for one to four weeks, although it has been known to take months for some people to fully recover. Diagnosis of mono is confirmed with blood testing - either a monospot test, or a full-blown blood test for EPV. Additional tests may be done to rule out other illnesses which can mimic mono.

What the Mono Blood Tests Look For

The mononucleosis tests are blood tests which look for antibodies in the blood which would indicate the presence of EBV. These antibodies are produced by the immune system in order to fight off infection and in an infected person the count is much higher than when no infection is present. The testing also helps the doctor know if you have ever been infected with the virus in the past or if the infection you are fighting is recent. The EBV test is done when the monospot test comes back negative and it can also be done to check for antibodies to EBV, if a person has a disease of the immune system or uses medications which affect the immune system.

The Heterophil Test (Monospot)

The heterophil test, or Monospot test, detects a type of antibody that is present in certain kinds of infections. A sample of blood is mixed with other substances and placed under a microscope. If heterophil antibodies are present in the blood, then the blood clumps or agglutinates. This usually indicates a mono infection. This type of testing is most effective in detecting recent infection - occurring not more than six months prior to the test.

Antibody Testing May Reveal More than Mono

In Epstein-Barr antibody testing, the blood is drawn from a vein and the results are given in liters, unlike the heterophil test. A liter measures how much dilution of the blood is required before the virus can no longer be detected. For instance, a liter of 1 to 40 means that antibodies can be found when one part of the blood sample is diluted by 40 parts of saline (salt water) solution. If the second number is larger, then there is an increased presence of the virus in the blood.

The EBV antibody test is also able to tell what kind of antibodies, or immunoglobins, are in the blood and whether the infection is recent or older.


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