Outcomes of ME/CFS following infectious mononucleosis: seven-year follow-up of a prospective study.

Background: Many individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) report experiencing an infectious illness prior to disease onset. Approximately 30% of cases are linked to Epstein-Barr virus (EBV) infection resulting in Infectious Mononucleosis (IM). Methods: We examined the progression of ME/CFS following IM among a cohort of college students who were recruited before they developed the infection. This sample represented a socioeconomically and ethnically diverse population of young adults who were monitored over a 7-year period. Assessments of health status, psychological functioning, and blood biomarkers were conducted at four time points: (1) baseline, when participants were healthy and at least 6 weeks from IM onset; (2) within 6 weeks of IM diagnosis; (3) 6 months post-IM, when participants had either recovered or met criteria for ME/CFS; and (4) the 7-year follow-up. Results: At follow-up, 81% of participants who had initially presented with severe ME/CFS continued to fulfill diagnostic criteria. In contrast, only about one-third of those with moderate or lingering symptoms at 6 months still had ME/CFS 7 years later. Conclusion: These findings indicate that ME/CFS following IM tends to persist over the long term, particularly among those whose illness was more severe at onset.