Okay, connect these dots: HHV-6, CFS, MS and (drum roll) AIDS.
"MS and CFS/ME are two common conditions with increased prevalence in
middle aged females. As the diagnosis of CFS/ME is clinical with no
positive clinical signs or investigations; it can be made with
difficulty in the presence of another clear explanation for the
disabling fatigue. Our results suggest that the two conditions may
co-exist. Considering CFS/ME as a potential co-morbidity may lead to
more focused and appropriate management."
http://www.ncbi.nlm.nih.gov/pubmed/25238862
http://www.ncbi.nlm.nih.gov/pubmed/25238862