Switzer, William M, Jia, Hongwei, Hohn, Oliver et al. · Retrovirology · 2010 · DOI
Researchers tested blood samples from 51 ME/CFS patients and 56 healthy people to see if a virus called XMRV was present. Using multiple sensitive tests from different laboratories, they found no evidence of this virus in either group. This study contradicted an earlier claim that XMRV was found in most ME/CFS patients.
Early claims that XMRV caused ME/CFS generated significant hope but also concern among patients. This rigorous multi-laboratory study provided crucial evidence that XMRV was not associated with ME/CFS, helping redirect research efforts toward other potential biological mechanisms and preventing misdirected clinical treatments.
This study does not prove that viruses are not involved in ME/CFS pathogenesis, only that this particular virus (XMRV) is not a consistent finding in US ME/CFS populations. The study also cannot exclude the possibility that XMRV might be relevant in specific subgroups or geographic regions not represented in this sample.
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
Switzer, William M, Jia, Hongwei, Hohn, Oliver, Zheng, HaoQiang, Tang, Shaohua, Shankar, Anupama, et al. (2010). Absence of evidence of xenotropic murine leukemia virus-related virus infection in persons with chronic fatigue syndrome and healthy controls in the United States.. Retrovirology. https://doi.org/10.1186/1742-4690-7-57
BibTeX
@article{mecfsatlas-switzer-2010-absence-evidence,
author = {Switzer, William M and Jia, Hongwei and Hohn, Oliver and Zheng, HaoQiang and Tang, Shaohua and Shankar, Anupama and Bannert, Norbert and Simmons, Graham and Hendry, R Michael and Falkenberg, Virginia R and Reeves, William C and Heneine, Walid},
title = {Absence of evidence of xenotropic murine leukemia virus-related virus infection in persons with chronic fatigue syndrome and healthy controls in the United States.},
journal = {Retrovirology},
year = {2010},
doi = {10.1186/1742-4690-7-57},
note = {PubMed: 20594299},
url = {https://www.mecfsatlas.com/evidence/switzer-2010-absence-evidence},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/switzer-2010-absence-evidence
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