E2 ModerateModerate confidencePEM not requiredObservationalPeer-reviewedReviewed
No findings of enteroviruses in Swedish patients with chronic fatigue syndrome.
Lindh, G, Samuelson, A, Hedlund, K O et al. · Scandinavian journal of infectious diseases · 1996 · DOI
Quick Summary
Researchers tested 34 Swedish patients with ME/CFS to see if a virus called enterovirus might be causing their illness. They looked for the virus in stool samples, blood, spinal fluid, and muscle tissue using several different detection methods. The study found no evidence of enterovirus infection in any of the patients tested.
Why It Matters
This study directly addresses a prominent hypothesis in ME/CFS research—that persistent enteroviral infection drives the disease. A negative finding helps narrow the search for ME/CFS etiology and redirects investigation toward other potential biological mechanisms.
Observed Findings
- No enteroviruses detected in any fecal samples (n=25 samples tested) using viral isolation techniques
- No enterovirus identified in muscle biopsy PCR analysis (n=29 patients)
- No cross-reactive enterovirus IgG antibodies found in serum-cerebrospinal fluid pairs (n=7 tested)
- Sampling occurred evenly across seasons to account for potential seasonal variation
Inferred Conclusions
- Persistent enterovirus infection is not a consistent finding in Swedish ME/CFS patients
- The proposed mechanism of immune complex disease mediated by chronic enterovirus was not supported in this cohort
- Alternative etiological mechanisms should be investigated
Remaining Questions
- Do enterovirus findings differ in non-Swedish populations or in geographically distinct ME/CFS cohorts?
- Could acute rather than chronic enterovirus infection be relevant to ME/CFS pathogenesis?
- Are there ME/CFS patient subgroups that might show different enterovirus serology or molecular findings?
- What alternative viral or non-viral mechanisms might explain ME/CFS symptoms in populations where enteroviruses are absent?
What This Study Does Not Prove
This study does not prove that enteroviruses play no role in ME/CFS globally or in all patient subpopulations. It only represents findings in a specific Swedish cohort; absence of evidence is not evidence of absence, particularly given the limited sample size and specific detection window.
Tags
Symptom:Fatigue
Biomarker:AutoantibodiesBlood Biomarker
Phenotype:Infection-Triggered
Method Flag:No ControlsSmall SampleExploratory OnlyPEM Not DefinedWeak Case Definition
Metadata
- DOI
- 10.3109/00365549609027178
- PMID
- 8863367
- Review status
- Editor reviewed
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 12 April 2026
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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