What is Infectious Mononucleosis?

Infectious Mononucleosis (IM) is a viral disease that affects certain types of white blood cells. It is caused by the Epstein-Barr Virus (EBV), a member of the Herpes family. While anyone might contract the illness, Mono is most commonly seen in young adults between the ages of 15 and 30, especially those living in close contact to schools, colleges and military bases. Mono may occur year round, but most cases develop in fall and early spring.

Symptoms of Mono include sore throat, fatigue, fever, headache, swollen glands, enlarged spleen and liver, and malaise. Many illnesses present similar symptoms as Mono; therefore, Mono tests have been designed to identify IgM heterophil antibodies specific to Infectious Mononucleosis.

Serologic results for persons with infectious mononucleosis include an elevated white blood cell count, an increased percentage of certain atypical white blood cells, and a positive reaction to a "mono spot" test.

When "mono spot" or heterophil test results are negative, additional laboratory testing may be needed to differentiate EBV infections from a mononucleosis-like illness induced by cytomegalovirus, adenovirus, or Toxoplasma gondii. Direct detection of EBV in blood or lymphoid tissues is a research tool and is not available for routine diagnosis. Instead, serologic testing is the method of choice for diagnosing primary infection.

What is IgM?

IgM, Immunoglobulin M (one of five classes of immunoglobulins) is a large molecule found in blood and is involved in combating blood infections and in triggering immunoglobin G production. Immunoglobin G is the main antibody defense against most bacterial invasions and other antigens.


The ASI Color Mono II Test is a slide agglutination assay for the qualitative and the semiquantitative detection of heterophil antibodies, in human serum, associated with infectious mononucleosis. No initial dilution of patient samples is required for this test. These materials are intended to be acquired, possessed and used only by health professionals.