Rasa, Santa, Nora-Krukle, Zaiga, Chapenko, Svetlana et al. · The new microbiologica · 2014
Researchers tested blood and brain tissue samples from people with ME/CFS, people with other brain conditions, and healthy people to see if they carried a virus called XMRV. The virus had been suspected as a possible cause of ME/CFS. The study found no evidence of XMRV in any of the samples tested, suggesting this particular virus is not present in ME/CFS patients.
Early reports suggesting XMRV involvement in ME/CFS generated significant hope and concern, making replication studies critical for understanding disease etiology. This negative finding helps clarify the role (or lack thereof) of XMRV in ME/CFS and directs research toward other potential viral and biological mechanisms. For patients, ruling out specific infectious agents is important for refocusing therapeutic development efforts.
This study does not prove that ME/CFS has no viral cause—only that XMRV specifically is not detected using these methods. A negative result could reflect true absence of the virus or limitations in detection methods, sample types, or timing of testing. The study also does not address whether other retroviruses or pathogens might be involved in ME/CFS pathogenesis.
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
Rasa, Santa, Nora-Krukle, Zaiga, Chapenko, Svetlana, Krumina, Angelika, Roga, Silvija, & Murovska, Modra (2014). No evidence of XMRV provirus sequences in patients with myalgic encephalomyelitis/chronic fatigue syndrome and individuals with unspecified encephalopathy.. The new microbiologica. https://pubmed.ncbi.nlm.nih.gov/24531167/
BibTeX
@article{mecfsatlas-rasa-2014-evidence-xmrv,
author = {Rasa, Santa and Nora-Krukle, Zaiga and Chapenko, Svetlana and Krumina, Angelika and Roga, Silvija and Murovska, Modra},
title = {No evidence of XMRV provirus sequences in patients with myalgic encephalomyelitis/chronic fatigue syndrome and individuals with unspecified encephalopathy.},
journal = {The new microbiologica},
year = {2014},
note = {PubMed: 24531167},
url = {https://www.mecfsatlas.com/evidence/rasa-2014-evidence-xmrv},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/rasa-2014-evidence-xmrv
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