Arredondo, Miguel, Hackett, John, de Bethencourt, Fermín R et al. · AIDS research and human retroviruses · 2012 · DOI
Researchers tested blood samples from over 1,100 people in Spain, including those with ME/CFS and fibromyalgia, to look for a virus called XMRV that had been suggested as a possible cause of these conditions. They found no reliable evidence that XMRV was present in any of the groups they studied, including people with ME/CFS, cancer, other viral infections, or healthy blood donors.
This study is important because early reports suggested XMRV might be linked to ME/CFS, raising hope for a viral explanation. A large, well-designed study finding no XMRV in ME/CFS patients helps clarify that this particular virus is unlikely to be a major cause, refocusing research efforts on other potential mechanisms.
This study does not prove that no virus is involved in ME/CFS—only that XMRV specifically was not detected in this Spanish population. The negative findings in a single country do not exclude XMRV's presence in other geographic populations, nor do they rule out other infectious agents. Cross-sectional serological testing has inherent limitations in sensitivity and specificity.
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
Arredondo, Miguel, Hackett, John, de Bethencourt, Fermín R, Treviño, Ana, Escudero, Domingo, Collado, Antonio, et al. (2012). Prevalence of xenotropic murine leukemia virus-related virus infection in different risk populations in Spain.. AIDS research and human retroviruses. https://doi.org/10.1089/AID.2011.0149
BibTeX
@article{mecfsatlas-arredondo-2012-prevalence-xenotropic,
author = {Arredondo, Miguel and Hackett, John and de Bethencourt, Fermín R and Treviño, Ana and Escudero, Domingo and Collado, Antonio and Qiu, Xiaoxing and Swanson, Priscilla and Soriano, Vincent and de Mendoza, Carmen},
title = {Prevalence of xenotropic murine leukemia virus-related virus infection in different risk populations in Spain.},
journal = {AIDS research and human retroviruses},
year = {2012},
doi = {10.1089/AID.2011.0149},
note = {PubMed: 22206583},
url = {https://www.mecfsatlas.com/evidence/arredondo-2012-prevalence-xenotropic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/arredondo-2012-prevalence-xenotropic
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