For the sake of completeness I will lpost the link to this paper which was found by
@Snow Leopard and posted on another thread
https://sci-hub.st/10.1093/clinids/13.Supplement_1.S138
Medical Aspects of Delayed Convalescence
Leighton E. Cluff
From the Robert Wood Johnson Foundation, Princeton, New Jersey
Disease and illness are not synonymous. In most instances, disease is demonstrable by anatomic, physiologic, biochemical, microbiologic, or immunologic abnormalities. Disease is a pathologic process. Not all persons with a disease are sick or ill. Symptoms of illness associated with a disease may be manifest or persist after the disease has disappeared. The absence of demonstrable disease, however, does not necessarily mean that symptoms of illness are unreal. Recovery from disease and recovery from illness are not always equated. Many factors, including personal characteristics and social circumstances, can be responsible for recovery from disease and illness. Chronic fatigue syndrome or symptoms of illness can persist in some patients but not in others after many different diseases.
Reviews of Infectious Diseases 1991;13(Suppl l):St38-46 © 1991 by The University of Chicago.
It is interesting that Cluff's former John Hopkins colleague Eisenberg brought these ides to the UK in 1987 and Cluff is still preaching them in 1991.
It is also interesting to note Cluffs interest in the Department of Veterans Affairs, given how closely connected to the military SW was to become.