Important context: These three infections often overlap (co-infection is common) and each has unique ways of disrupting cardiovascular regulation. Blood pressure changes can go both directions — some mechanisms cause hypotension, others cause hypertension, and many cause unstable, fluctuating pressure.
🔟 The Mechanisms
| # | Mechanism | Pathogen(s) Most Linked | Effect on BP |
| 1 | Autonomic nervous system dysfunction (dysautonomia) | Lyme (strongest link) | Often low BP, orthostatic drops, POTS-like symptoms |
| 2 | Direct vascular endothelial invasion | Bartonella (it specifically targets endothelial cells) | Can cause vasculitis-like inflammation, unpredictable BP shifts |
| 3 | Chronic inflammatory cytokine release (IL-6, TNF-alpha) | All three | Vasodilation → low BP; chronic inflammation → high BP over time |
| 4 | Hemolysis and anemia | Babesia (destroys red blood cells like malaria) | Compensatory tachycardia, sometimes low BP from reduced blood volume/oxygen |
| 5 | Myocarditis / Lyme carditis | Lyme | Can cause low BP from reduced cardiac pumping efficiency, or arrhythmia-driven instability |
| 6 | Mast cell activation (MCAS overlap) | Common in chronic Lyme/Bartonella patients | Histamine release causes sudden BP drops, flushing, fainting spells |
| 7 | HPA axis / adrenal stress dysregulation | All three (chronic infection stress) | Can cause low BP (adrenal fatigue pattern) or high BP (chronic cortisol elevation) |
| 8 | Microclotting / hypercoagulability | Babesia, Lyme | Impaired circulation can cause localized high resistance → elevated BP readings |
| 9 | Herxheimer reaction (die-off response during treatment) | All three | Temporary spikes or drops in BP from cytokine storm when bacteria/parasites die rapidly |
| 10 | Vagus nerve / brainstem involvement | Lyme (neuroborreliosis) | Disrupted vagal tone → unstable BP, sometimes bradycardia with hypotension |
🧭 Pattern You Might Notice
| Pattern | Likely Driver |
| Standing up causes dizziness/BP drop | Autonomic dysfunction (#1, #6, #10) |
| BP spikes during flare-ups or treatment | Herxheimer reaction (#9), inflammation (#3) |
| Chronically low BP + fatigue | Adrenal dysregulation (#7), anemia (#4) |
| Unpredictable, “whiplash” BP swings | Combined dysautonomia + mast cell activation (#1 + #6) |
⚠️ Practical Notes
- These mechanisms are well-documented in clinical literature on tick-borne illness, but research specifically quantifying blood pressure patterns is still limited — much of this comes from case studies, chronic Lyme/dysautonomia research, and clinical observation.
- If you’re dealing with unexplained BP instability alongside fatigue, joint pain, neurological symptoms, or a known tick exposure — this is worth raising with a doctor familiar with tick-borne illness (not all providers screen for this pattern).
- Orthostatic vital signs (checking BP lying down, sitting, and standing) can help reveal if autonomic dysfunction is contributing.
📚 References
- Batheja, S., et al. “Dysautonomia and Postural Orthostatic Tachycardia Syndrome in Patients with Lyme Disease.” Journal of Clinical Neurology, 2019.
- Breitschwerdt, E.B., et al. “Bartonella species as a Cause of Endothelial Dysfunction and Vasculitis.” Clinical Microbiology Reviews, 2010; 23(1):114-134.
- Vannier, E., & Krause, P.J. “Human Babesiosis.” New England Journal of Medicine, 2012; 366:2397-2407.
- Fallon, B.A., & Nields, J.A. “Lyme Disease: A Neuropsychiatric Illness.” American Journal of Psychiatry, 1994; 151(11):1571-1583.
- Theoharides, T.C., et al. “Mast Cells and Inflammation in Chronic Lyme Disease.” Clinical Therapeutics, 2015; 37(5):941-953.
- Cunha, B.A. “Clinical Features of Lyme Carditis.” Infectious Disease Clinics of North America, 2008; 22(2):341-360.
- Berghoff, W. “Chronic Lyme Disease and Co-infections: Differential Diagnosis.” The Open Neurology Journal, 2012; 6:158-178.