1984 Chapel Hill outbreak
"In the mid-1980s, chronic fatigue syndrome was first identified as a cluster of symptoms in clusters of patients in a few spots in the United States. Dr. Charles Lapp, then a family physician in Raleigh, N.C., identified one such outbreak among all the members of the N.C. Symphony Orchestra. [emphasis added] Seven remained ill with chronic fatigue [at the time this article was written in 2009].
'Patients started coming to me with persistent flulike symptoms,' said Lapp, now medical director of Hunter-Hopkins Center in Charlotte, N.C. 'They would work one day and have to sleep for two. Perfectly well-adjusted people became disabled almost overnight.'
"... a series of studies at the University of Pittsburgh Cancer Center focused on an apparent outbreak of a fatiguing illness involving members of a symphony orchestra in North Carolina (Grufferman et al.,1988; Eby et al., 1989). The studies documented four cases of cancer (B-cell non-Hodgkins's lymphoma, glioblastoma multiforme, acinic cell carcinoma, and breast cancer) among the orchestra members and close contacts. The cancer cases had lower levels of activity, as compared to controls, of activity of natural killer cells, a set of white blood cells that can directly kill cancer cells." 
- [http://newsok.com/article/3366622 "Cause of illness remains unknown," By Karen Garloch Published: The Oklahoman, May 5, 2009]
- "Medical Etiology, Assessment, and Treatment of Chronic Fatigue and Malaise," by Roberto Patarca-Montero, published by CRC Press, Oct 29, 2004, pp 83-84.