<i>Babesia</i> and <i>Bartonella</i> Species DNA in Blood and Enrichment Blood Cultures from People with Chronic Fatigue and Concurrent Neurological Symptoms.

Evidence Atlas

Babesia and Bartonella Species DNA in Blood and Enrichment Blood Cultures from People with Chronic Fatigue and Concurrent Neurological Symptoms.

Breitschwerdt, Edward B, Maggi, Ricardo G, Bush, Janice C et al. · Pathogens (Basel, Switzerland) · 2025 · DOI

Quick Summary

This study looked for two types of bacteria—Babesia and Bartonella—in the blood of 50 people with ME/CFS and neurological symptoms. Researchers used special DNA tests to detect these bacteria. They found that about 24% of participants had Babesia infection and 26% had Bartonella infection, suggesting these bacteria might play a role in some ME/CFS cases.

Why It Matters

This research addresses a long-standing clinical observation that some ME/CFS patients may have concurrent tick-borne infections, potentially explaining a subset of ME/CFS cases. If Babesia or Bartonella contribute to ME/CFS symptoms in some patients, identifying and treating these infections could lead to improved outcomes for affected individuals. The study provides preliminary evidence justifying further investigation into infection-associated ME/CFS.

Observed Findings

12 of 50 participants (24%) tested positive for Babesia species DNA
13 of 50 participants (26%) tested positive for Bartonella species DNA
2 participants had concurrent infection with both Babesia and Bartonella species
All study participants reported fatigue lasting 6 months to 19 years and at least one neurological symptom

Inferred Conclusions

Babesia and Bartonella species infections may play a role in ME/CFS presentations in some patients
The combined prevalence of these two pathogens in ME/CFS patients warrants further investigation
Prospective case-control studies with sensitive pathogen detection are needed to clarify the relationship between these infections and ME/CFS

Remaining Questions

How do infection rates in this ME/CFS cohort compare to infection rates in age-matched healthy controls or non-ME/CFS patient populations?
Do patients with confirmed Babesia or Bartonella infection show different symptom patterns, severity, or treatment responses compared to ME/CFS patients without these infections?
What is the temporal relationship between infection and ME/CFS symptom onset—do these infections precede, coincide with, or follow the development of ME/CFS?

What This Study Does Not Prove

This study does not prove that Babesia or Bartonella cause ME/CFS, nor does it establish that these infections are necessary or sufficient for ME/CFS development. Without a control group of healthy individuals or those with other conditions, the study cannot determine whether these infection rates are higher in ME/CFS patients than in the general population. The cross-sectional design establishes association only, not causation.

Metadata

DOI: 10.3390/pathogens15010002
PMID: 41598986
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 →