Tonsils in glandular fever. Close up of inflamed, pus-covered tonsils in a patient with glandular fever (infectious mononucleosis). This acute viral infection is caused either by the Epstein- Barr virus or cytomegalovirus, both of which are members of the herpesvirus family. Once in the body the virus multiplies inside lymphocyte white blood cells. Symptoms include high fever, sore throat and swollen lymph nodes, particularly in the neck. The diagnosis is made by a blood smear or a test for antibodies. Most patients recover within 4-6 weeks but frequently feel tired and run-down for a further two or three months. The uvula (centre) is seen between the two tonsils.