Heterophile antibody test

The mononuclear spot test or monospot test, a form of the heterophile antibody test, is a rapid test for infectious mononucleosis due to Epstein–Barr virus (EBV). It is an improvement on the Paul-Bunnell test. The test is specific for heterophile antibodies produced by the human immune system in response to EBV infection. Commercially available test kits are 70-92% sensitive and 96-100% specific, with a lower sensitivity in the first two weeks after clinical symptoms begin. It will generally not be positive during the 4-6 week incubation period before the onset of symptoms. It will also not generally be positive after active infection has subsided, even though the virus persists in the same cells in the body for the rest of the carrier's life.