Kondo, Kazuhiro · Nihon rinsho. Japanese journal of clinical medicine · 2007
This study looked at whether two common viruses that hide dormant in our bodies (HHV-6 and HHV-7) wake up and become active during fatigue. Researchers found that healthy people shed more HHV-6 in their saliva when tired from work, but ME/CFS patients did not show this pattern. However, HHV-7 did increase in both groups, suggesting these viruses might be useful markers to measure fatigue objectively.
ME/CFS lacks objective diagnostic biomarkers, making diagnosis challenging and delayed. If viral reactivation patterns can reliably distinguish ME/CFS from normal fatigue, this could enable earlier diagnosis and more targeted treatment approaches. Understanding the differential reactivation of HHV-6 versus HHV-7 in ME/CFS may also illuminate underlying immune dysfunction in the disease.
This study does not prove that HHV-6 or HHV-7 *causes* ME/CFS—only that reactivation patterns differ. The correlation between viral shedding and fatigue does not establish causation. The study also does not explain *why* ME/CFS patients lack HHV-6 reactivation or what mechanisms drive the observed HHV-7 elevation in this population.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Kondo, Kazuhiro (2007). [Chronic fatigue syndrome and herpesvirus reactivation].. Nihon rinsho. Japanese journal of clinical medicine. https://pubmed.ncbi.nlm.nih.gov/17561695/
BibTeX
@article{mecfsatlas-kondo-2007-chronic-fatigue,
author = {Kondo, Kazuhiro},
title = {[Chronic fatigue syndrome and herpesvirus reactivation].},
journal = {Nihon rinsho. Japanese journal of clinical medicine},
year = {2007},
note = {PubMed: 17561695},
url = {https://www.mecfsatlas.com/evidence/kondo-2007-chronic-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/kondo-2007-chronic-fatigue
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