FAS and HHV-7 infectious disease: In another study involving 17 ME/CFS patients, HHV-7 reactivation was detected more frequently than HHV-6 reactivation and concurrent active HHV-6 and HHV-7 infection was accompanied by immunological changes in the form of significantly increased CD95+ cells, decreased CD3+ and CD4+ T cells, and a lower CD4/CD8 ratio [64].