virus infections promoting chronic fatigue can be diagnosed by assessing the 2 &# 39 ;- 5 &# 39 ; a / rnase l pathway , including measurement of 2 &# 39 ;- 5 &# 39 ; a oligonucleotide levels in the patient &# 39 ; s circulating peripheral leucocytes , and comparing these resuls with those of healthy individuals . double - stranded rnas , notably mismatched dsrnas , when administered in appropriate amounts , increase the 2 &# 39 ;- 5 &# 39 ; a and normalize the antiviral pathway in patients with chronic fatigue syndrome and improve the clinical symptoms .