Maes, Michael, Mihaylova, Ivana, Leunis, Jean-Claude · Journal of affective disorders · 2007 · DOI
This study found that people with ME/CFS have higher levels of immune antibodies (IgA and IgM) that react against bacteria normally found in the gut. The researchers suggest this indicates the gut barrier may be more permeable (leaky), allowing bacterial products to enter the bloodstream and trigger an immune response. The study suggests testing for these antibodies might help identify and treat this potential gut problem in ME/CFS patients.
Understanding potential gut barrier dysfunction and bacterial involvement in ME/CFS could open new diagnostic and treatment approaches. If validated, antibody testing against these bacteria might help identify a biomarker for a subset of ME/CFS patients and guide targeted interventions addressing intestinal permeability.
This study does not prove that enterobacteria or gut permeability causes ME/CFS—it only shows an association. The cross-sectional design cannot determine whether increased antibodies precede ME/CFS symptoms or result from the illness. The study also does not demonstrate that treating gut permeability would improve ME/CFS symptoms.
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
Maes, Michael, Mihaylova, Ivana, & Leunis, Jean-Claude (2007). Increased serum IgA and IgM against LPS of enterobacteria in chronic fatigue syndrome (CFS): indication for the involvement of gram-negative enterobacteria in the etiology of CFS and for the presence of an increased gut-intestinal permeability.. Journal of affective disorders. https://doi.org/10.1016/j.jad.2006.08.021
BibTeX
@article{mecfsatlas-maes-2007-increased-serum,
author = {Maes, Michael and Mihaylova, Ivana and Leunis, Jean-Claude},
title = {Increased serum IgA and IgM against LPS of enterobacteria in chronic fatigue syndrome (CFS): indication for the involvement of gram-negative enterobacteria in the etiology of CFS and for the presence of an increased gut-intestinal permeability.},
journal = {Journal of affective disorders},
year = {2007},
doi = {10.1016/j.jad.2006.08.021},
note = {PubMed: 17007934},
url = {https://www.mecfsatlas.com/evidence/maes-2007-increased-serum},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-27. https://www.mecfsatlas.com/evidence/maes-2007-increased-serum
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