Nicolson, G L, Gan, R, Haier, J · APMIS : acta pathologica, microbiologica, et immunologica Scandinavica · 2003 · DOI
This study tested the blood of 200 ME/CFS patients and 100 healthy controls for three types of infections: Mycoplasma bacteria, Chlamydia bacteria, and human herpesvirus-6 (HHV-6). The researchers found that ME/CFS patients had significantly higher rates of these infections compared to healthy people, and patients with multiple infections at the same time tended to have more severe symptoms.
This study provides evidence that multiple concurrent infections may be present in a substantial subset of ME/CFS patients and could contribute to disease severity. Understanding infection patterns in ME/CFS could inform both diagnostic approaches and targeted treatment strategies, potentially benefiting patients with infection-associated ME/CFS.
This study does not establish that these infections cause ME/CFS—only that they are more common in patients with the condition. The cross-sectional design cannot determine whether infections preceded symptom onset or developed afterward, and the lack of correlation between specific infection types and symptoms suggests infections may not fully explain ME/CFS pathology. The study does not rule out other contributing biological factors.
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 →
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