A mononucleosis spot test (monospot test) is a screening test for
mononucleosis. The test detects a type of antibody (heterophil antibody) that
forms during certain infections, especially during infection with the
For this test, a sample of blood is placed on a microscope slide
and mixed with other substances. If heterophil antibodies are present, the
blood clumps. This result usually points to a mono infection.
The test can usually find a mono infection in about 2 to 9 weeks
after the person has been exposed to the virus. The antibodies are proteins
made by the immune system to fight the infection. After they have formed,
antibodies usually remain in a person's blood for life.
E. Gregory Thompson, MD - Internal Medicine & Adam Husney, MD - Family Medicine & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease