A method of diagnosing a subset of Epstein Barr Virus, Myalgic Encephalomyelitis Chronic Fatigue Syndrome (ME/CFS) patients through a multi-prong clinical/serological analysis is provided wherein Epstein Barr Virus Abortive Lytic Replication (EBV) is determined as the specific causal agent through the use of serum antibodies to EBV encoded dUTPase and serum antibodies to EBV DNA Polymerase as molecular markers. A method of treating patients diagnosed with Epstein Barr Virus Abortive Lytic Replication (EBV), Myalgic Encephalomyelitis Chronic Fatigue Syndrome (ME/CFS) with specific antiviral nucleosides is also provided, to alleviate the condition.