Tarello, W · Comparative immunology, microbiology and infectious diseases · 2001 · DOI
This study looked at 15 dogs and cats that had fatigue symptoms similar to ME/CFS and tested their blood for bacterial infections. Nine out of 15 animals had a type of bacteria called Staphylococcus in their blood. When these animals were treated with an antibiotic drug, all of them got completely better and the bacteria disappeared from their blood.
This study raises the possibility that CFS-like conditions might be associated with persistent bacterial infection and bacteremia, which could have implications for understanding potential infectious triggers in human ME/CFS patients. If validated in larger human populations, this could suggest new diagnostic approaches and treatment avenues for a condition where the underlying cause remains unclear.
This study does not establish that bacterial infection causes ME/CFS in humans—it is limited to 15 animals with only 2 meeting strict CFS diagnostic criteria. The complete remission with arsenical treatment does not prove causation; it demonstrates correlation in this small group and does not necessarily apply to human ME/CFS populations. Additionally, findings in animals do not directly translate to human disease mechanisms without rigorous human validation studies.
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
Tarello, W (2001). Chronic Fatigue Syndrome (CFS) in 15 dogs and cats with specific biochemical and microbiological anomalies.. Comparative immunology, microbiology and infectious diseases. https://doi.org/10.1016/s0147-9571(00)00025-4
BibTeX
@article{mecfsatlas-tarello-2001-chronic-fatigue-2,
author = {Tarello, W},
title = {Chronic Fatigue Syndrome (CFS) in 15 dogs and cats with specific biochemical and microbiological anomalies.},
journal = {Comparative immunology, microbiology and infectious diseases},
year = {2001},
doi = {10.1016/s0147-9571(00)00025-4},
note = {PubMed: 11440190},
url = {https://www.mecfsatlas.com/evidence/tarello-2001-chronic-fatigue-2},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/tarello-2001-chronic-fatigue-2
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