Mast cells are immune cells distributed throughout the body that serve as a first line of defense against pathogens and environmental threats, releasing over 200 chemical mediators (including histamine, prostaglandins, and cytokines) when activated. In Mast Cell Activation Syndrome (MCAS), these cells become hyper-responsive and degranulate inappropriately in response to various triggers, leading to widespread, multisystem inflammation that can manifest as allergic-type reactions (hives, flushing, anaphylaxis), gastrointestinal issues, neurological symptoms, pain, fatigue, and more.
Infections, particularly chronic ones, are among the most potent triggers for mast cells, causing them to remain in a persistently activated state and driving ongoing symptoms even after the initial infection has been partially treated. In patients with Lyme disease and co-infections such as Bartonella, Babesia, Dr. Tania Dempsey, MD, an internationally recognized expert in MCAS, explains that these vector-borne illnesses frequently trigger or exacerbate MCAS, often explaining why many individuals fail to fully improve with antimicrobial therapy alone. Bartonella, in particular, is highlighted as a major culprit, with its ability to persist intracellularly and provoke intense mast cell responses, leading to neuroinflammation, chemical sensitivities, flares during treatment, and overlap with conditions like autoimmunity or hypermobility. Stabilizing mast cells with targeted therapies (H1/H2 blockers, mast cell stabilizers, low-histamine diets, etc.) while simultaneously addressing the underlying infections is crucial for recovery, as untreated MCAS can perpetuate a cycle of inflammation, symptom flares, and treatment resistance in this patient population.
