Lyme disease vs MCAS: symptoms, biomarkers, trials and researchliterature-only comparison
A data-driven comparison of Lyme Disease and Mast Cell Activation Syndrome (MCAS) built from the Open Source Medicine Foundation biomarker atlases, PubMed literature feeds, ClinicalTrials.gov registry extract and post-acute infection syndrome (PAIS) cohort database.
A registered trial of mast-cell treatment for post-tick-bite illness is the most direct link between these conditions; otherwise the connection rests on case reports of MCAS following Lyme disease.
No biomarker atlas exists for MCAS, so the biomarker sections below are limited to the other condition. This page compares literature, trials, therapeutics and cohorts.
What each condition is
Lyme Disease
Also known as: Lyme borreliosis, Borrelia burgdorferi infection, Post-treatment Lyme disease syndrome (PTLDS), Chronic Lyme
Lyme disease is a tick-borne bacterial infection caused by Borrelia burgdorferi and related species. Early disease is diagnosed by the erythema migrans rash and two-tier serology, and treated with antibiotics. A minority of treated patients develop post-treatment Lyme disease syndrome (PTLDS): fatigue, musculoskeletal pain and cognitive symptoms lasting six months or longer. The OSMF literature feed for this condition focuses on the chronic and post-treatment phase, while the biomarker atlas spans acute serology through neuroborreliosis and persistent-symptom phenotypes.
Atlas scope: Serologic, cerebrospinal fluid, molecular, and inflammatory biomarkers in Borrelia burgdorferi infection — from early localized disease through disseminated, neuroborreliosis, and post-treatment persistent symptom phenotypes.
OSMF resources: biomarker atlas · literature feed
Mast Cell Activation Syndrome
Also known as: Mast cell activation disorder
MCAS is characterised by episodic, multi-system symptoms (flushing, hives, gastrointestinal upset, wheeze, hypotension) caused by inappropriate release of mast-cell mediators, with laboratory evidence such as a rise in serum tryptase during an episode and a response to mast-cell-directed therapy. Diagnostic criteria remain contested between consensus groups. MCAS is frequently reported alongside POTS, hypermobility and post-infectious illness; OSMF follows it through a literature feed and clinical-trial registry rather than a dedicated biomarker atlas.
OSMF resources: literature feed
Side-by-side summary
| Measure | Lyme disease | MCAS |
|---|---|---|
| Biomarkers catalogued | 36 | No atlas |
| Biomarker categories covered | serologic (9), csf (6), inflammatory (6), molecular (4), coinfection (4), chronic (4), functional (3) | — |
| Markers with LOINC codes | 6 | — |
| Literature studies tracked | 75 | 75 |
| Most recent tracked study | 05 Jul 2026 | 10 Jul 2026 |
| Registered trials (all statuses) | 2 | 5 |
| Recruiting / not yet recruiting | 2 | 1 |
| Active, not recruiting | 0 | 0 |
| Completed | 0 | 1 |
| Terminated / withdrawn / suspended | 0 | 2 |
| Unknown status | 0 | 1 |
| Named cohorts in PAIS database | 1 | 0 |
| Therapeutic agents tracked | 8 | 11 |
Trial condition matching: Lyme disease uses keyword matching on registry condition and title fields; MCAS uses keyword matching on registry condition and title fields. Trials listing both conditions: 0.
Biomarkers catalogued for Lyme disease
MCAS has no OSMF biomarker atlas, so no shared-marker matching is possible. The Lyme disease atlas lists 36 markers; the 15 most relevant to this comparison are shown (autonomic, immune, inflammatory and vascular categories first).
- Interleukin-6 (IL-6) Increased inflammatory
- Interleukin-10 (IL-10) Increased inflammatory
- Interferon-γ (IFN-γ) Increased inflammatory
- C-Reactive Protein (CRP) Mixed / conflicting inflammatory
- CCL19 Increased inflammatory
- ESR (erythrocyte sedimentation rate) Mixed / conflicting inflammatory
- Liver enzymes (ALT/AST) Mixed / conflicting functional
- Facial palsy + CSF pleocytosis Increased functional
- Lyme arthritis RF/anti-CCP Decreased functional
- B. burgdorferi EIA (screening) Increased serologic
- IgG immunoblot (≥5 of 10 bands) Increased serologic
- IgM immunoblot (≥2 of 3 bands) Increased serologic
- C6 peptide ELISA (VisE) Increased serologic
- Anti-VlsE antibodies Increased serologic
- Anti-OspC antibodies Increased serologic
Browse the full Lyme disease atlas.
Overlapping therapeutics under investigation (2)
Agents that appear in registered trials or the OSMF therapeutic-agent database for both Lyme disease and MCAS. Inclusion means an agent is being studied, not that it works.
- Cromolyn Sodium
- Ketotifen
Research cohorts
Lyme disease cohorts (1)
- Johns Hopkins SLICE early-Lyme cohort (Aucott/Rebman) prospective inception, n=234, biobank active
MCAS cohorts (0)
No named cohort for this condition in the PAIS database yet.
Recent research
Latest Lyme disease studies
Latest MCAS studies
Frequently asked questions
Can you have both Lyme disease and MCAS?
Yes. MCAS is a syndrome diagnosed on clinical criteria and can be diagnosed in someone who also has Lyme disease; 0 registered trials in the OSMF registry list both conditions, and they share 2 therapeutic agents under investigation.
How do the biomarker profiles differ?
OSMF does not maintain a biomarker atlas for MCAS, which is diagnosed by physiological or clinical criteria rather than a laboratory panel, so this is a literature-level comparison. Lyme disease has 36 catalogued markers across 7 categories (most often serologic, csf, inflammatory).
Which has more active clinical trials?
Lyme disease has more: 2 active or recruiting trials versus 1 for MCAS (registry snapshot 07 Oct 2026). Totals including completed, terminated and unknown-status studies are 2 for Lyme disease and 5 for MCAS. Condition matching for Lyme disease, MCAS relies on keyword matching of registry condition fields and may miss trials. Trial counts measure research attention, not treatment efficacy.
Which condition has more recent research?
OSMF tracks 75 recent PubMed-indexed studies for Lyme disease (latest 05 Jul 2026) and 75 for MCAS (latest 10 Jul 2026). The feeds hold a rolling window of recent publications, so they indicate current publication pace rather than lifetime output. See the Lyme disease feed and the MCAS feed for the full lists.
Are the same treatments being studied for both?
2 agents appear in the trial registry or therapeutic-agent database for both conditions, including Cromolyn Sodium, Ketotifen. All of these are investigational for these indications; none is an approved treatment for either condition. Overlap usually reflects shared hypotheses (immune modulation, autonomic support, antiviral or anti-inflammatory strategies) rather than demonstrated efficacy.
Which has larger research cohorts?
The PAIS cohort database lists 1 named cohort for Lyme disease and 0 named cohorts for MCAS, the largest being Johns Hopkins SLICE early-Lyme cohort (Aucott/Rebman) (234 enrolled). Cohorts with stored biospecimens and open external access are the most useful for cross-condition biomarker validation.
Related comparisons
Cite this page
@misc{osmf_lyme_vs_mcas,
author = {Open Source Medicine Foundation},
title = {Lyme disease vs MCAS: symptoms, biomarkers, trials and research compared},
year = {2026},
howpublished = {\url{https://research.opensourcemed.info/compare/lyme-vs-mcas.html}},
note = {Data as of 2026-10-07}
}Get OSMF research updates
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Last updated 07 Oct 2026 (page build). Underlying data: literature feeds 08 Jul 2026 / 10 Jul 2026; trial registry 07 Oct 2026; atlases 29 Jun 2026 / n/a. Generated by scripts/build_compare_pages.py.