Chronic fatigue syndrome (CFS) is currently defined by clinical signs and symptoms
including debilitating fatigue that is not attributable to other known clinical conditions, by flu-
like symptoms (eg, pharyngitis, adenopathy, low-grade fever, myalgia, arthralgia, headache)
and by neuropsychological manifestations (eg, difficulty concentrating, exercise intolerance,
and sleep disturbances). CFS is frequently of sudden onset. Its etiology is unknown.
Although immunologic abnormalities are frequently described in the literature of CFS, there …