Fatigue for Diagnosis of Epstein Barr Virus Infectious Mononucleosis Fatigue is a significant feature of EBV infectious mononucleosis. It is the most initial symptom of EBV infection. Other symptoms may resolve within 2-4 weeks but fatigue persists for many weeks and even months. Patients are provided treatment which resolves the infection but fatigue persists without other symptoms of EBV infection.