The frequent association of an active viral infection with the
symptoms of CFS led researchers to hypothesize that chronic
fatigue syndrome (CFS) is induced by a virus. Results of these
studies indicated that despite clinical support for this
hypothesis, there were no clear data linking viruses to CFS.
In this overview, we will explore the interrelation of the
immune, endocrine, and central nervous systems, and the
possibility that stress and/or the reactivation/replication of
a latent virus (such as Epstein-Barr virus) could modulate the
immune system to induce CFS. Relevant research conducted in
the developing field of psychoneuroimmunology will be
reviewed, with a particular focus on cytokine synthesis,
natural killer (NK) cell activity, and T- lymphocyte function,
as they relate to CFS.