Chronic fatigue syndrome in northern Nevada.

The clinical and laboratory findings from studies of patients with chronic fatigue syndrome (CFS) from northern Nevada are summarized. Physicians caring for these patients have estimated that greater than 400 patients with CFS from northern Nevada and nearby communities in California were identified between 1984 and 1988. As a result of these studies, a cluster of clinical and laboratory features associated with the illness in moderately to severely affected patients has been identified: profound fatigue of prolonged duration; cervical lymphadenopathy; recurrent sore throat and/or symptoms of influenza; loss of cognitive function manifested by loss of memory and loss of ability to concentrate; myalgia; impairment of fine motor skills; abnormal findings on magnetic resonance imaging brain scan; depressed level of antibody to Epstein-Barr virus (EBV) nuclear antigen; elevated level of antibody to EBV early antigen restricted component; elevated ratio of CD4 helper to CD8 suppressor cells; and strong evidence of association of this syndrome with infection with human herpesvirus 6. More-serious and longer-lasting neurologic impairments, including seizures, psychosis, and dementia, have also been observed in some of these patients.