Positive serological tests for infectious mononucleosis in a patient with Mediterranean spotted fever.

The Monospot test is an accurate and reliable test for infectious mononucleosis. False positive reactions have been seldom recorded. We report the conversion of the Monospot test from negative to positive during the course of Mediterranean spotted fever. Changes in the titre of the Paul-Bunnell test were observed also. The importance of measuring IgM antibodies as part of the routine investigation of infectious diseases is emphasised.