Lyme Disease

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Subtypes

4

Early Localized Lyme Disease

Initial stage within weeks of tick bite, characterized by erythema migrans and flu-like symptoms.

Show evidence (1 reference)

PMID:38651851 SUPPORT Human Clinical

"Early localized stage. Characterized by skin changes - erythema migrans (EM) - usually manifests within a month of the tick bite (usually 7-14 days after the bite)"

Review describes early localized stage as defined by erythema migrans appearing within weeks of the tick bite.

Early Disseminated Lyme Disease

Hematogenous spread within weeks to months, with multiple erythema migrans, neurological, or cardiac involvement.

Show evidence (1 reference)

PMID:38651851 SUPPORT Human Clinical

"Lyme disease has a wide spectrum of clinical manifestations that can generally be observed in three stages: the early localized stage, the early disseminated stage, and the late stage of the disease."

Clinical review delineates Lyme disease into three classical stages including an early disseminated stage.

Late Disseminated Lyme Disease

Months to years after infection, characterized by Lyme arthritis or chronic neurological manifestations.

Show evidence (1 reference)

PMID:38651851 SUPPORT Human Clinical

"Lyme disease has a wide spectrum of clinical manifestations that can generally be observed in three stages: the early localized stage, the early disseminated stage, and the late stage of the disease."

Clinical review documents the late stage of Lyme disease as a distinct phase following early dissemination.

Post-Treatment Lyme Disease Syndrome

Persistent symptoms after appropriate antibiotic therapy, occurring in 10-20% of treated patients.

Show evidence (1 reference)

PMID:39161484 SUPPORT Human Clinical

"These symptoms occur in 10%-20% of patients previously diagnosed with LD caused by the bacteria Borrelia burgdorferi and appropriately treated with a course of antibiotics."

IDSA-aligned review confirms PTLDS occurs in 10–20% of appropriately treated Lyme disease patients.

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Pathophysiology

12

Borrelial Ribosomal Translation (Doxycycline Target)

Borrelia burgdorferi depends on 70S-ribosome translation. Doxycycline, the first-line agent for early localized and early disseminated Lyme disease, binds the 30S subunit and arrests bacterial protein synthesis — a ribosomal target distinct from the PBP target of the beta-lactam alternatives.

Translation GO:0006412

Show evidence (1 reference)

PMID:24336183 SUPPORT Other

"The ribosome is one of the main antibiotic targets in the bacterial cell."

Establishes the bacterial ribosome as the doxycycline (tetracycline) target, the step this node represents. Evidence source is OTHER as this is a review.

Borrelial Peptidoglycan Cross-Linking (Beta-Lactam Target)

Borrelia burgdorferi maintains its peptidoglycan cell wall by penicillin-binding protein (PBP) transpeptidase cross-linking. This essential, bacteria-specific reaction is the target of the amoxicillin and ceftriaxone used to treat Lyme disease; beta-lactam acylation of the PBP active site halts cross-linking and is bactericidal against disseminating spirochetes. CNS penetration of ceftriaxone is what extends this mechanism to neuroborreliosis.

Peptidoglycan-Based Cell Wall Biogenesis GO:0009273

Show evidence (1 reference)

PMID:22203377 SUPPORT Other

"although glycan chain polymerization occurs in the absence of transpeptidation (for example, in the presence of penicillin), efficient transpeptidation requires ongoing GTase reactions"

Establishes that beta-lactams act by blocking PBP transpeptidation, the cross-linking step this node represents. Evidence source is OTHER as this is a review article.

Tick-Borne Transmission and Enzootic Cycle

Borrelia burgdorferi is maintained in an enzootic cycle between Ixodes ticks and small-mammal reservoirs such as the white-footed mouse; larval ticks acquire spirochetes by feeding on infected reservoirs and transmit them transstadially to the nymphal stage that bites humans. In the unfed tick midgut the spirochete expresses OspA (midgut adhesion) but not OspC. During the blood meal, host- and temperature-derived signals trigger a reciprocal antigenic switch in which OspA is downregulated and OspC is upregulated, accompanying spirochete migration from the midgut to the salivary glands and transmission into the vertebrate dermis; OspC expression peaks around 48 h of tick attachment and is required for early mammalian infectivity.

OspA/OspC antigenic switch GO:0010468 response to temperature stimulus GO:0009266

Downstream

Spirochete Invasion and Dissemination OspC-mediated transmission deposits infectious spirochetes in the host dermis, initiating local colonization and dissemination.

Show evidence (2 references)

PMID:10618120 SUPPORT Model Organism

"B. burgdorferi expresses outer surface protein A (OspA) but not OspC when residing in the midgut of unfed ticks. However, after ticks feed on blood, some spirochetes stop making OspA and express OspC."

Immunofluorescence of spirochetes in feeding Ixodes nymphs demonstrates the reciprocal OspA-to-OspC switch that accompanies transmission from tick to mammal.

PMID:22230951 SUPPORT Other

"we integrate this large body of information into a cohesive picture of the molecular and cellular events that transpire as Lyme disease spirochaetes transit between their arthropod and vertebrate hosts during the enzootic cycle."

Authoritative review frames B. burgdorferi pathogenesis around its dual-host transit between Ixodes ticks and vertebrate hosts during the enzootic cycle.

Tick Saliva-Assisted Immune Evasion via Salp15-OspC

During transmission, Borrelia burgdorferi co-opts components of Ixodes tick saliva to establish infection at the bite site. The spirochete selectively enhances tick expression of the 15-kDa salivary protein Salp15, which binds the spirochetal surface lipoprotein OspC and coats the organism. Salp15 (and its I. ricinus homologue Iric1) shields Borrelia from antibody-mediated killing and complement, giving the spirochete a marked infectivity advantage in the mammalian host; the bacterium thereby exploits a secreted arthropod protein to colonize the vertebrate dermis.

Salp15-mediated protection from antibody-mediated killing GO:0042783 ↑ INCREASED

skin UBERON:0002097

Downstream

Spirochete Invasion and Dissemination Salp15-coated spirochetes resist early humoral clearance at the bite site, enabling establishment of dermal infection and subsequent dissemination.

Show evidence (2 references)

PMID:16049492 SUPPORT Model Organism

"Salp15 was then shown to adhere to the spirochaete, both in vitro and in vivo, and specifically interacted with B. burgdorferi outer surface protein C. The binding of Salp15 protected B. burgdorferi from antibody-mediated killing in vitro and provided spirochaetes with a marked advantage when..."

RNA-interference and infection experiments in Ixodes scapularis and mice show B. burgdorferi usurps the tick salivary protein Salp15, which binds OspC and protects the spirochete from antibody-mediated killing during transmission.

PMID:33401196 SUPPORT In Vitro

"we show in this study that also Iric2 and Iric3 are capable of OspC binding with high affinity"

Binding study demonstrates that, beyond the previously characterized Iric1, the I. ricinus Salp15 homologues Iric2 and Iric3 also bind Borrelia OspC with high affinity, reinforcing Salp15-family/OspC engagement as a conserved transmission-interface interaction.

Spirochete Invasion and Dissemination

Borrelia burgdorferi is transmitted through Ixodes tick bites. The spirochete disseminates from the skin through the bloodstream to multiple organ systems including joints, heart, and nervous system. Surface adhesins like BBK32 and decorin-binding proteins (DbpA/DbpB) facilitate tissue colonization, while OspC is upregulated at the tick-feeding/early-mammalian interface and is required for early infectivity.

endothelial cell CL:0000115

cell adhesion GO:0007155

skin UBERON:0002097 blood UBERON:0000178

Downstream

Inflammatory Response and Tissue Damage Disseminating spirochetes deliver lipoproteins and peptidoglycan that drive innate inflammation at colonized tissues.

Erythema Migrans Centrifugal migration of spirochetes outward through the dermis at the bite site produces the characteristic expanding erythema migrans rash of early localized infection.

Show evidence (1 reference)

PMID:33669940 SUPPORT

"The clinical manifestations of Lyme disease range from a localized infection, for example, erythema migrans (EM) to a disseminated neurological or rheumatological infection, cardiac involvement, or even chronic disease."

Epidemiologic series shows Borrelia disseminates beyond skin to neurologic, rheumatologic, and cardiac sites.

Complement Evasion via BBK32-Mediated C1r Inhibition

The Borrelia burgdorferi surface lipoprotein BBK32 binds C1r, the initiator protease of the classical complement pathway. This attenuates antibody-dependent complement activation and protects infectious Borrelia from complement-mediated killing in human serum.

negative regulation of complement activation GO:0045916 ↑ INCREASED

Downstream

Spirochete Invasion and Dissemination Blocking antibody-dependent complement killing allows surviving spirochetes to disseminate despite humoral immunity.

Show evidence (1 reference)

PMID:40705830 SUPPORT In Vitro

"BBK32 binds to C1r, the initiator protease of the classical pathway of complement, and protects B. burgdorferi from complement-mediated killing following exposure to normal human serum."

Functional in vitro evidence that BBK32 binds C1r and blocks classical-pathway complement killing of infectious Borrelia burgdorferi.

Alternative Complement Pathway Evasion via Factor H Recruitment

Borrelia burgdorferi expresses complement regulator-acquiring surface proteins (CRASPs) such as CspA (CRASP-1), along with CspZ and OspE-family paralogs, that bind the host alternative-pathway regulators factor H and factor H-like protein 1 (FH/FHL-1). Surface-bound FH/FHL-1 limits C3 deposition and membrane-attack-complex formation, conferring resistance to complement-mediated killing in human serum. This pathway complements the BBK32-mediated classical-pathway block.

negative regulation of complement activation GO:0045916 ↑ INCREASED

Downstream

Spirochete Invasion and Dissemination Alternative-pathway evasion sustains spirochete viability in serum, supporting hematogenous spread.

Show evidence (1 reference)

PMID:19451251 SUPPORT In Vitro

"the CspA-mediated binding of human FH confers serum resistance by directly inhibiting complement deposition on the surface of B. burgdorferi."

A cspA knockout loses surface factor H binding and becomes serum-sensitive with enhanced C3/C6/C5b-9 deposition, demonstrating CspA-driven alternative-pathway evasion.

Antigenic Variation via vlsE Gene Conversion

The vlsE locus undergoes gene conversion that diversifies Borrelia surface antigens, helping the pathogen evade host immune recognition during dissemination and persistent infection.

DNA recombination GO:0006310 ↑ INCREASED

Downstream

Spirochete Invasion and Dissemination Antigenic variation maintains an immune-evasive, persistent infection that supports continued tissue colonization.

Show evidence (1 reference)

PMID:39792948 SUPPORT In Vitro

"Borrelia burgdorferi, the Lyme disease pathogen, has evolved an intricate antigenic variation mechanism to evade the host immune response, enabling its dissemination, persistence, and pathogenicity."

Mechanistic study of the vlsE locus confirms antigenic variation as the immune-evasion mechanism enabling B. burgdorferi persistence.

Host Lipid Scavenging and Membrane Biogenesis

Borrelia burgdorferi is a metabolically compromised spirochete (~1.5 Mbp genome) that cannot survive without host-derived lipids: it lacks de novo sterol synthesis and most lipid-biosynthetic capacity, requires exogenous cholesterol for growth and viability, and must scavenge lipids from the tick and vertebrate host to build and remodel its LPS-free, lipoprotein-rich cell envelope during the enzootic cycle. A multi-platform untargeted and targeted LC-MS/GC-MS lipidomic compendium detected more than 500 lipids in B. burgdorferi, the majority sourced from the environment through apparently discriminatory uptake (some species depleted 600-1500-fold during growth). The pathogen organizes neutral lipids — cholesteryl esters and triglycerides — into distinct intracellular foci (the first visual/molecular evidence of lipid-droplet-like storage in this minimal bacterium), and incorporates host sphingolipids and ceramides, with phosphatidylcholine established as a principal membrane constituent alongside cholesterol and cholesterol galactolipids (AcGal) that form cholesterol/sphingolipid lipid rafts. Unexpectedly, the spirochete also biosynthesizes predominantly eukaryotic lipids: four lysosomal bis(monoacylglycerol)phosphate (BMP) species (proposed roles in membrane plasticity/stress adaptation), phosphatidylglycerol and phosphatidylethanolamine, the plant galactolipid monogalactosyl diacylglycerol (MGDG; against which late-stage Lyme patients mount an antibody response), an acylated glycosylated phytosterol (acylhexosylcampesterol from scavenged campesterol), and the plant-type anionic sulfolipid sulfoquinovosyl diacylglycerol (SQDG). Structural-homology modeling against Arabidopsis SQD1/SQD2 and heterologous E. coli reconstitution identified two interdependent B. burgdorferi enzymes, BB0444 and BB0454, as sufficient for SQDG biosynthesis (BB0454 also makes MGDG); homologs are broadly conserved across spirochetes and >30 Borrelia species. This "lipid chimera" strategy of intensive scavenging plus niche biosynthesis is essential for envelope integrity and persistence, nominating lipid acquisition, sulfolipid synthesis, and neutral- lipid storage as candidate antimicrobial targets.

host lipid acquisition GO:0006869 ↑ INCREASED host cholesterol import GO:0070508 ↑ INCREASED cholesteryl ester and triglyceride storage in intracellular foci GO:0019915 ↑ INCREASED sulfoquinovosyl diacylglycerol (SQDG) biosynthesis GO:0046506 ↑ INCREASED

Downstream

Spirochete Invasion and Dissemination Lipid scavenging and residual biosynthesis maintain the spirochete cell envelope, supporting survival and dissemination in the vertebrate host.

Show evidence (6 references)

PMID:42239376 SUPPORT In Vitro

"belongs to a class of metabolically compromised bacteria that cannot survive without host-derived lipids"

Lipidomic study establishes B. burgdorferi as a lipid auxotroph dependent on host-derived lipids for survival.

PMID:42239376 SUPPORT In Vitro

"The analysis detected more than 500 lipids in"

Untargeted and targeted high-resolution mass spectrometry profiled a compendium of more than 500 lipids in the spirochete.

PMID:42239376 SUPPORT In Vitro

"the bacterium selectively accumulates certain lipids while excluding others, suggesting discriminatory uptake. These include cholesteryl esters and triglycerides that are organized in foci within the pathogen"

The spirochete shows discriminatory lipid uptake, concentrating cholesteryl esters and triglycerides into intracellular foci.

+ 3 more references

Inflammatory Response and Tissue Damage

The host immune response to Borrelia antigens contributes to tissue damage. Spirochetal lipoproteins and peptidoglycan trigger robust innate immune activation with production of IL-6, IL-8, TNF, and chemokines (CCL3/CCL4). Persistent inflammation in joints may continue even after spirochete clearance.

neutrophil CL:0000775 macrophage CL:0000235 T cell CL:0000084

inflammatory response GO:0006954

synovial membrane UBERON:0002018

Downstream

Arthralgia Inflammatory cytokines and immune-cell infiltration in and around joints produce the arthralgia that commonly precedes frank arthritis.

Arthritis Neutrophilic and lymphocytic synovial inflammation driven by Borrelia antigens produces the mono/oligoarticular inflammatory arthritis of Lyme disease.

Facial Palsy Immune-mediated cranial neuritis of the facial nerve produces unilateral or bilateral facial palsy.

Atrioventricular Block Inflammation of the cardiac conduction system disrupts AV nodal conduction, producing variable-degree atrioventricular block.

Myelitis Inflammatory involvement of the spinal cord during acute neuroborreliosis produces myelitis.

Dementia (Reversible Neuroborreliosis) CNS inflammation in neuroborreliosis produces a subcortical/reversible dementia syndrome that improves with antibiotic therapy.

Fatigue Systemic pro-inflammatory cytokines (IL-6, TNF) produce the profound constitutional fatigue seen across disease stages.

Autoimmune Activation after Persistent Infection Sustained antigen-driven inflammation is proposed to break self-tolerance in genetically predisposed hosts.

Post-Infectious Immune Dysregulation Tissue damage and inflammation from viable or nonviable spirochetes are a proposed driver of persistent post-treatment symptoms.

Show evidence (1 reference)

PMID:37407232 SUPPORT

"Aspiration of the left knee joint revealed a white cell count of 21.0×109/L (83% neutrophils) with negative Gram stain and culture. However, Lyme PCR was positive and accompanied by serologies consistent with Lyme arthritis."

Lyme arthritis joint fluid shows marked neutrophilic inflammation despite negative cultures, consistent with immune-driven damage.

Autoimmune Activation after Persistent Infection

Prolonged exposure of the host immune system to Borrelia antigens can drive post-infectious autoimmunity, with reported triggers of systemic autoimmune disease after Lyme borreliosis.

T cell CL:0000084

adaptive immune response GO:0002250

Downstream

Post-Infectious Immune Dysregulation Post-infectious autoimmune responses are one of the leading proposed mechanisms underlying persistent post-treatment symptoms.

Arthritis Post-infectious autoimmunity drives antibiotic-refractory Lyme arthritis that persists despite eradication of viable spirochetes.

Bullous Skin Lesions Post-infectious autoimmunity is a proposed trigger for the rare autoimmune blistering (EBA-like) skin lesions reported after Lyme disease.

Show evidence (1 reference)

PMID:34786243 SUPPORT

"long-term exposure of the host's immune system to spirochetes can contribute to the development of chronic autoimmune disease de novo."

Case review links persistent Borrelia exposure to downstream autoimmune disease.

Post-Infectious Immune Dysregulation

In an estimated 10-20% of appropriately treated patients, symptoms such as fatigue, pain, and cognitive complaints persist for more than six months (post-treatment Lyme disease syndrome, PTLDS). The mechanism is not fully established; proposed drivers include an autoimmune response to spirochete-induced tissue damage and inflammation, broader immune dysfunction, and persistent viable or nonviable antigen. This node is a terminal post-infectious state rather than ongoing high-burden active infection in most cases.

T cell CL:0000084 B cell CL:0000236

inflammatory response GO:0006954

Downstream

Fatigue Persistent immune dysregulation underlies the chronic fatigue that is a core symptom of post-treatment Lyme disease syndrome.

Show evidence (2 references)

PMID:39161484 SUPPORT Human Clinical

"We propose that ongoing PTLDS symptoms seem to be related to an autoimmune response to the tissue damage and inflammation caused by the viable or nonviable spirochete pathogen."

IDSA-aligned clinical review proposes post-infectious autoimmune/immune-dysregulation mechanisms for persistent PTLDS symptoms.

PMID:27358211 SUPPORT Human Clinical

"Receiver operating characteristic analysis identified a CCL19 cutoff of >111.67 pg/ml at 1 month following treatment completion to be 82% sensitive and 83% specific for later PTLDS."

Prospective cohort identifies persistently elevated posttreatment levels of the T-cell chemokine CCL19 as an immunologic risk marker for PTLDS, supporting ongoing immune-driven dysregulation rather than resolved infection.

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Pathograph

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Phenotypes

9

Cardiovascular 2

Erythema Migrans VERY_FREQUENT Erythema migrans HP:0031180

Show evidence (1 reference)

PMID:33669940 SUPPORT

"Results: In total, 1005 patients were enrolled with the following prevalence of clinical syndromes: erythema migrans (EM), 945 (94.02%); Lyme arthritis, 32 (3.18%); neuroborreliosis, 23 (2.28%); Lyme carditis, 4 (0.39%); and acrodermatitis, 1 (0.09%)."

Large Lithuanian cohort confirms erythema migrans as the dominant presentation.

Atrioventricular Block OCCASIONAL Atrioventricular block HP:0001678

Show evidence (1 reference)

PMID:37234726 SUPPORT

"the most common clinical manifestation is AV block, which can be acute in onset and can rapidly progress to complete heart block."

Case report and review emphasize AV block as the hallmark of Lyme carditis.

Head and Neck 1

Facial Palsy OCCASIONAL Facial palsy HP:0010628

Show evidence (1 reference)

PMID:33669940 SUPPORT

"The main symptoms were the following: nervus facialis neuropathy (47.8%), myalgia (39%), head pain (26%), and radiculitis (21%)."

Neuroborreliosis cases frequently manifested facial nerve palsy.

Immune 1

Myelitis VERY_RARE Myelitis HP:0012486

Show evidence (1 reference)

PMID:33082765 SUPPORT

"We report a case of acute neuroborreliosis that manifested as extended isolated cervical myelitis."

Case report confirms Lyme-associated cervical myelitis with CSF pleocytosis and intrathecal Borrelia antibodies.

Integument 1

Bullous Skin Lesions VERY_RARE Subepidermal blistering HP:0033804

Show evidence (1 reference)

PMID:41133080 SUPPORT

"developed acquired epidermolysis bullosa (EBA) following an LD diagnosis. Initially, the patient presented with atypical erythema migrans, which later evolved into multiple bullous lesions"

Case report documents bullous lesions evolving after Lyme disease.

Musculoskeletal 1

Arthritis FREQUENT Arthritis HP:0001369

Show evidence (1 reference)

PMID:33669940 SUPPORT

"Lyme arthritis mainly manifested among middle-aged women as an oligoarthritis, mostly affecting the knee joint."

Cohort study documents oligoarticular knee-predominant Lyme arthritis.

Nervous System 1

Dementia (Reversible Neuroborreliosis) VERY_RARE Dementia HP:0000726

Show evidence (2 references)

PMID:30046879 SUPPORT

"Dementia-like syndromes are rare manifestations of Lyme neuroborreliosis... The response to 2-4 weeks of antibiotic treatment with ceftriaxone was excellent."

Review of definite neuroborreliosis cases shows dementia syndromes resolving after ceftriaxone.

PMID:36740841 SUPPORT

"Lyme disease is an uncommon cause of reversible dementia... the brilliant clinical improvement after the appropriate antimicrobial therapy is strongly suggestive for a diagnosis of neuroborreliosis."

Geriatric case of reversible dementia with marked improvement after antimicrobial therapy.

Constitutional 2

Fatigue FREQUENT Fatigue HP:0012378

Show evidence (2 references)

PMID:8644761 SUPPORT Human Clinical

"including fatigue (54%), arthralgia (44%), myalgia"

In a prospective cohort of 79 culture-confirmed erythema migrans patients, fatigue was the most common systemic symptom at 54%, which falls in the FREQUENT band (30-79%).

PMID:33669940 PARTIAL

"Clinical symptoms were as follows: arthralgia (33.2%), general weakness (19%), head pain (13.1%), myalgia (11.2%), fever (6.2%), joint swelling (5.9%), head dizziness (5.1%), nervus facialis neuropathy (2.4%), and radiculitis (2.0%)."

An ambulatory cohort reports general weakness at 19% (OCCASIONAL band); retained as a secondary, lower estimate that reflects cohort/definition variability.

Arthralgia FREQUENT Arthralgia HP:0002829

Show evidence (1 reference)

PMID:33669940 SUPPORT

"Clinical symptoms were as follows: arthralgia (33.2%), general weakness (19%), head pain (13.1%), myalgia (11.2%), fever (6.2%), joint swelling (5.9%), head dizziness (5.1%), nervus facialis neuropathy (2.4%), and radiculitis (2.0%)."

Arthralgia was reported in one-third of patients in a large endemic cohort.

🧬

Genetic Associations

1

HLA-DRB1 Susceptibility Alleles (Susceptibility)

Show evidence (1 reference)

PMID:39225104 SUPPORT Human Clinical

"the TCR-β motif was linked predominantly to HLA-DRB1*11 or 13 alleles, which differed from alleles in patients from North America."

Editorial highlights HLA-DRB1 allele linkage to T cell receptor motifs that distinguish antibiotic-refractory Lyme arthritis from other rheumatic diseases.

💊

Medical Actions

3

Oral Doxycycline

Action: Pharmacotherapy NCIT:C15986

Agent: doxycycline CHEBI:50845

First-line treatment for early localized and early disseminated Lyme disease in adults. Typical dose is 100mg twice daily for 10-21 days. Also provides prophylaxis for tick bites in endemic areas.

Mechanism Target:

INHIBITS Spirochete Invasion and Dissemination — Doxycycline is bactericidal against Borrelia burgdorferi, eradicating disseminating spirochetes and arresting the causal chain upstream of tissue inflammation and downstream manifestations.

INHIBITS Borrelial Ribosomal Translation (Doxycycline Target) — Doxycycline binds the 30S ribosome and arrests borrelial protein synthesis.

Target Phenotypes: Erythema migrans HP:0031180

Show evidence (1 reference)

PMID:17029130 SUPPORT

"Tables list the doses and durations of antimicrobial therapy recommended for treatment and prevention of Lyme disease"

IDSA guidelines provide evidence-based antibiotic treatment recommendations for Lyme disease.

Oral Amoxicillin

Action: Pharmacotherapy NCIT:C15986

Agent: amoxicillin CHEBI:2676

Alternative first-line agent for early Lyme disease, preferred in children under 8 years and pregnant women. Typical dose is 500mg three times daily.

Mechanism Target:

INHIBITS Spirochete Invasion and Dissemination — Amoxicillin is bactericidal against Borrelia burgdorferi, clearing disseminating spirochetes in early Lyme disease.

INHIBITS Borrelial Peptidoglycan Cross-Linking (Beta-Lactam Target) — Amoxicillin acylates the borrelial PBP transpeptidase, blocking peptidoglycan cross-linking.

Target Phenotypes: Erythema migrans HP:0031180

Show evidence (1 reference)

PMID:17176487 SUPPORT

"We describe a favorable outcome in a 42-year-old woman who developed Lyme disease in the third trimester and was treated with a full course of oral amoxicillin."

Case report in pregnancy shows successful treatment with amoxicillin.

Intravenous Ceftriaxone

Action: Pharmacotherapy NCIT:C15986

Agent: ceftriaxone CHEBI:29007

Recommended for neurological Lyme disease (neuroborreliosis), Lyme carditis with high-degree AV block, and some cases of Lyme arthritis. Duration typically 14-28 days.

Mechanism Target:

INHIBITS Spirochete Invasion and Dissemination — Ceftriaxone penetrates the CNS and is bactericidal against Borrelia burgdorferi, clearing spirochetes disseminated to the nervous system, heart, and joints.

INHIBITS Borrelial Peptidoglycan Cross-Linking (Beta-Lactam Target) — Ceftriaxone acylates the borrelial PBP transpeptidase, blocking peptidoglycan cross-linking; its CNS penetration extends this to neuroborreliosis.

Target Phenotypes: Facial palsy HP:0010628 Atrioventricular block HP:0001678 Myelitis HP:0012486 Dementia HP:0000726 Arthritis HP:0001369

Show evidence (1 reference)

PMID:37692616 SUPPORT

"The patient's symptoms resolved quickly with a four-day inpatient course of IV ceftriaxone followed by 10 days of oral doxycycline."

Neuroborreliosis case improved with intravenous ceftriaxone then doxycycline.

🌍

Environmental Factors

5

Tick Exposure

Ixodes scapularis (deer tick) in eastern North America, I. pacificus in western North America, I. ricinus in Europe

Geographic Location

Endemic areas include northeastern and upper midwestern United States, and parts of Europe and Asia

Seasonal Exposure

Peak transmission during late spring and summer months (May-August) when nymphal ticks are active

Show evidence (1 reference)

PMID:37075475 SUPPORT Other

"Nymphs were most active from May through August, with continuing low-level activity in October, and peak activity most commonly observed in June. The observed nymphal peak corresponded with the typical peak in reported human Lyme disease and anaplasmosis cases."

Field surveillance of Ixodes scapularis confirms that peak nymphal host-seeking from May–August aligns with the seasonal peak of human Lyme disease cases.

Outdoor Activities

Risk factors include hiking, camping, gardening, and activities in wooded or grassy areas

Show evidence (1 reference)

PMID:37075475 SUPPORT Other

"These findings are consistent with previous studies from the Upper Midwest and highlight a risk of human exposure to I. scapularis at least from April through November."

Seasonal tick surveillance highlights prolonged human exposure risk in woodland habitats during months when outdoor activity can lead to Ixodes contact.

Non-Ixodes Tick Exposure

Rare reports of dog tick (Rhipicephalus) transmission in India; underscores need to consider atypical vectors in endemic settings

Show evidence (1 reference)

PMID:36352974 SUPPORT

"we present the case of Lyme's disease in an adult male with dog tick, Rhipecephalus as a vector."

Case report documents Lyme transmission by Rhipicephalus dog tick, highlighting atypical vector risk.

🔬

Biochemical Markers

3

Anti-Borrelia Antibodies (IgM/IgG) (Detected)

Context: Two-tier testing with ELISA screening and Western blot confirmation; antibodies may take 2-4 weeks to develop

Show evidence (1 reference)

PMID:38651851 SUPPORT Human Clinical

"IgM and IgG specific for Borrelia burgdorferi was also performed: IgG was borderline, whereas IgM was positive at 218 U/mL."

Case demonstrates serological IgM/IgG detection against Borrelia burgdorferi as part of Lyme disease diagnosis.

Elevated ESR/CRP (Elevated)

Context: Markers of systemic inflammation, especially in disseminated disease

CSF Pleocytosis (Elevated)

Context: In neuroborreliosis, lymphocytic pleocytosis with elevated protein and intrathecal antibody production

Show evidence (1 reference)

PMID:42001681 SUPPORT Human Clinical

"accurate diagnosis of LNB requires cerebrospinal fluid (CSF) analysis, demonstrating pleocytosis and intrathecal synthesis of Bbsl-specific antibodies."

Lyme neuroborreliosis diagnosis is anchored on demonstrated CSF pleocytosis and intrathecal Bbsl-specific antibody synthesis.

🔀

Differential Diagnoses

7

Conditions with similar clinical presentations that must be differentiated from Lyme Disease:

Southern Tick-Associated Rash Illness (STARI) MONDO:0025294

Overlapping Features Lone star tick-associated erythema migrans–like rash without Borrelia burgdorferi infection.

Distinguishing Features

Occurs after Amblyomma americanum bite in southeastern/south-central US; Borrelia testing negative.
Typically lacks systemic neurologic or cardiac involvement seen in disseminated Lyme.

Show evidence (1 reference)

PMID:40788480 SUPPORT

"southern tick-associated rash illness (STARI)"

Highlights STARI as a distinct erythema migrans–like illness linked to lone star tick bites.

Cellulitis Not Yet Curated MONDO:0005230

Overlapping Features Bacterial skin infection that can mimic early erythema migrans.

Distinguishing Features

Painful, warm, expanding erythema often with fever.
No central clearing.
Responds rapidly to anti-staphylococcal/streptococcal therapy.

Show evidence (1 reference)

PMID:26437159 SUPPORT

"atypical vesicular features... resulted in multiple misdiagnoses and delayed treatment"

Atypical erythema migrans presentations can be misdiagnosed as bacterial cellulitis.

Septic Arthritis Not Yet Curated MONDO:0042485

Overlapping Features Acute bacterial arthritis of large joints.

Distinguishing Features

Very high synovial WBC with positive Gram stain/culture.
Lacks migratory arthralgias and Borrelia serology.
Requires urgent drainage.

Show evidence (1 reference)

PMID:24028811 SUPPORT

"clinical and biological picture often resembles that of septic arthritis"

Pediatric Lyme arthritis cases can initially be confused with septic arthritis.

Rheumatoid Arthritis MONDO:0008383

Overlapping Features Chronic symmetric inflammatory polyarthritis.

Distinguishing Features

Small-joint symmetric involvement with RF/anti-CCP positivity.
No tick exposure history or erythema migrans.
Nodules and erosions on imaging.

Show evidence (1 reference)

PMID:24028811 SUPPORT

"clinical and biological picture often resembles that of septic arthritis and juvenile rheumatoid arthritis"

Lyme arthritis may mimic rheumatoid patterns, prompting serologic differentiation.

Viral Encephalitis MONDO:0006009

Overlapping Features CNS infection causing encephalopathy that can overlap with neuroborreliosis symptoms.

Distinguishing Features

CSF PCR panels for HSV/VZV/arboviruses.
Absent Borrelia intrathecal antibodies.
Often acute febrile onset.

Show evidence (1 reference)

PMID:29848409 SUPPORT

"Two serum samples from one patient showed neutralizing antibodies against TBE virus."

Tick-borne encephalitis virus infection was found in a patient initially suspected of Lyme, illustrating viral encephalitis as a key differential.

Multiple Sclerosis and Other Demyelinating Myelopathies MONDO:0005301

Overlapping Features Demyelinating CNS disease that can mimic neuroborreliosis with cord lesions.

Distinguishing Features

Oligoclonal bands without intrathecal Borrelia antibodies.
Typical MS lesion distribution.
Relapsing course without tick exposure.

Show evidence (1 reference)

PMID:34861197 SUPPORT

"Examples... newly diagnosed included multiple sclerosis"

Cohort of presumed Lyme referrals identified multiple sclerosis as a frequent alternate diagnosis.

Viral Myocarditis/Other Causes of AV Block Not Yet Curated MONDO:0004496

Overlapping Features Cardiac conduction disease from viral myocarditis or idiopathic fibrosis.

Distinguishing Features

Elevated cardiac biomarkers and viral serologies.
Absence of erythema migrans or Lyme serology.
Persistent AV block without rapid reversal on antibiotics.

Show evidence (1 reference)

PMID:40385752 SUPPORT

"Comprehensive investigations excluded other bradyarrhythmia causes, such as Lyme disease, sarcoidosis, and myocarditis"

Case of dengue-related complete heart block underscores non-Lyme infectious causes of advanced AV block.

📊

Related Datasets

1

A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism DOI:10.64898/2026.05.22.727245

Untargeted and targeted high-resolution mass-spectrometry lipidomics of the Lyme disease spirochete Borrelia burgdorferi, profiling more than 500 membrane and storage lipids and tracing their host/environmental origin versus residual de novo biosynthesis. Identifies discriminatory lipid uptake, cholesteryl ester and triglyceride accumulation in intracellular foci, and biosynthesis of eukaryotic-type lipids (bis(monoacylglycerol)phosphate and sulfoquinovosyl diacylglycerol), nominating lipid acquisition and synthesis pathways as survival-critical antimicrobial targets.

Borrelia burgdorferi METABOLOMICS Multi-platform LC-MS (Orbitrap,...

Conditions: In vitro-cultured Borrelia burgdorferi (BSK-II medium with 6% rabbit serum)

Findings

Borrelia burgdorferi is a lipid auxotroph that cannot survive without host-derived lipids.

"belongs to a class of metabolically compromised bacteria that cannot survive without host-derived lipids"

More than 500 lipids were detected, the majority sourced from the environment via discriminatory uptake.

"The analysis detected more than 500 lipids in"

Neutral lipids (cholesteryl esters and triglycerides) are organized into distinct intracellular foci — the first evidence of lipid-droplet-like storage in this minimal bacterium.

"neutral lipids are organized into distinct intracellular foci"

Phosphatidylcholine is a principal membrane constituent alongside cholesterol and cholesterol galactolipids.

"phosphatidylcholine as one of the principal membrane constituents alongside cholesterol and cholesterol galactolipids"

Four lysosomal bis(monoacylglycerol)phosphate (BMP) species, absent from the medium, are biosynthesized by the pathogen.

"We identified four BMPs in B. burgdorferi that were entirely absent from the CM"

The interdependent enzymes BB0444 and BB0454 are sufficient for biosynthesis of the plant-type sulfolipid SQDG (confirmed by heterologous expression in E. coli).

"we discovered two enzymes, BB0444 and BB0454, in B. burgdorferi that are sufficient for the synthesis of SQDG"

PMID:42239376

Preprint dataset (bioRxiv DOI:10.64898/2026.05.22.727245; also PMID:42239376 / PMC13228262). Lipidomics is recorded under the METABOLOMICS data_type because the schema has no dedicated lipidomics value. The evidence snippets are exact quotes from the published abstract; the additional `findings` supporting_text quotes are drawn from the full-text preprint PDF.

Show evidence (1 reference)

PMID:42239376 SUPPORT In Vitro

"we used a suite of untargeted and targeted high-resolution mass spectrometry methods to reveal a complex lipid profile of the pathogen and to identify the origin of its lipids"

Describes the untargeted and targeted high-resolution MS lipidomics workflow that generated this dataset.

🔬

Clinical Trials

3

NCT03769194 PHASE_II COMPLETED

Randomized, controlled, observer-blind Phase 2 study evaluating immunogenicity and safety of VLA15, a multivalent recombinant OspA-based Lyme borreliosis vaccine candidate in healthy adults aged 18-65 years. Participants received 3 immunizations at monthly intervals.

Target Phenotypes: Erythema migrans HP:0031180

Show evidence (1 reference)

clinicaltrials:NCT03769194 SUPPORT

"The study was investigated 3 doses of a multivalent OspA (Outer Surface Protein A) based Lyme vaccine (VLA15) in healthy adults aged 18 to 65 years of age. Study participants received 3 immunizations of the vaccine at a monthly interval."

This Phase 2 trial evaluates VLA15, a preventive vaccine targeting OspA surface protein, offering evidence for active immunization against Lyme borreliosis.

NCT06785402 PHASE_II RECRUITING

Randomized, double-blind, placebo-controlled Phase 1/2 trial evaluating pulse-dosed intravenous ceftriaxone for Post-Treatment Lyme Disease Syndrome (PTLDS). Investigates whether periodic high-dose antibiotic therapy can eliminate persistent Borrelia burgdorferi in patients with persistent symptoms.

Target Phenotypes: Fatigue HP:0012378 Arthralgia HP:0002829

Show evidence (1 reference)

clinicaltrials:NCT06785402 SUPPORT

"Lyme disease is a public health crisis in the US. It is estimated that over 400,000 cases occur every year with 10-20% of those infected going on to develop Post-Treatment Lyme disease Syndrome (PTLDS). The goal of this study is to investigate if giving Ceftriaxone every 5 days for about 6 weeks..."

This Phase 1/2 trial directly addresses post-treatment Lyme disease syndrome with a novel pulse-dosing regimen, providing clinical evidence for managing antibiotic-refractory cases.

NCT03584919 NOT_APPLICABLE COMPLETED

European prospective clinical trial comparing doxycycline and cefuroxime axetil for treatment of erythema migrans in adult patients. Participants were evaluated at baseline, 14 days, and 2, 6, and 12 months post-enrollment to assess treatment efficacy and long-term outcomes.

Target Phenotypes: Erythema migrans HP:0031180

Show evidence (1 reference)

clinicaltrials:NCT03584919 SUPPORT

"A European, prospective clinical trial in which doxycycline and cefuroxime axetil were compared in the treatment of adult patients with erythema migrans included a control group to address this question. Evaluations of patients were conducted at baseline, 14 days and 2, 6, and 12 months after enrollment."

This comparative trial evaluates two oral antibiotics for early Lyme disease, providing evidence for treatment options and long-term symptom outcomes in erythema migrans patients.

{ }

Source YAML

click to show

name: Lyme Disease
creation_date: '2026-01-09T05:55:26Z'
updated_date: '2026-05-02T00:00:00Z'
category: Infectious Disease
description: >
  Lyme disease is a tick-borne infectious disease caused by Borrelia burgdorferi
  and related Borrelia species. It is the most common vector-borne disease in
  North America and Europe. The disease progresses through stages: early localized
  (erythema migrans), early disseminated (multiple erythema migrans, neurological,
  cardiac involvement), and late disseminated (arthritis, chronic neurological).
  Early antibiotic treatment is highly effective, while delayed treatment may lead
  to persistent symptoms.
disease_term:
  preferred_term: Lyme disease
  term:
    id: MONDO:0019632
    label: Lyme disease
parents:
- Bacterial Infection
- Tick-Borne Disease
has_subtypes:
- name: Early Localized Lyme Disease
  description: Initial stage within weeks of tick bite, characterized by erythema migrans and flu-like symptoms.
  evidence:
  - reference: PMID:38651851
    reference_title: "Skin Changes in Suspected Lyme Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early localized stage. Characterized by skin changes - erythema migrans (EM) - usually manifests within a month of the tick bite (usually 7-14 days after the bite)"
    explanation: Review describes early localized stage as defined by erythema migrans appearing within weeks of the tick bite.
- name: Early Disseminated Lyme Disease
  description: Hematogenous spread within weeks to months, with multiple erythema migrans, neurological, or cardiac involvement.
  evidence:
  - reference: PMID:38651851
    reference_title: "Skin Changes in Suspected Lyme Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lyme disease has a wide spectrum of clinical manifestations that can generally be observed in three stages: the early localized stage, the early disseminated stage, and the late stage of the disease."
    explanation: Clinical review delineates Lyme disease into three classical stages including an early disseminated stage.
- name: Late Disseminated Lyme Disease
  description: Months to years after infection, characterized by Lyme arthritis or chronic neurological manifestations.
  evidence:
  - reference: PMID:38651851
    reference_title: "Skin Changes in Suspected Lyme Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lyme disease has a wide spectrum of clinical manifestations that can generally be observed in three stages: the early localized stage, the early disseminated stage, and the late stage of the disease."
    explanation: Clinical review documents the late stage of Lyme disease as a distinct phase following early dissemination.
- name: Post-Treatment Lyme Disease Syndrome
  description: Persistent symptoms after appropriate antibiotic therapy, occurring in 10-20% of treated patients.
  evidence:
  - reference: PMID:39161484
    reference_title: "What Makes It Tick: Exploring the Mechanisms of Post-treatment Lyme Disease Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These symptoms occur in 10%-20% of patients previously diagnosed with LD caused by the bacteria Borrelia burgdorferi and appropriately treated with a course of antibiotics."
    explanation: IDSA-aligned review confirms PTLDS occurs in 10–20% of appropriately treated Lyme disease patients.
pathophysiology:
- name: Borrelial Ribosomal Translation (Doxycycline Target)
  description: >-
    Borrelia burgdorferi depends on 70S-ribosome translation. Doxycycline, the
    first-line agent for early localized and early disseminated Lyme disease, binds
    the 30S subunit and arrests bacterial protein synthesis — a ribosomal target
    distinct from the PBP target of the beta-lactam alternatives.
  role: therapeutic_vulnerability
  conforms_to: "bacterial_protein_synthesis_inhibition#Bacterial mRNA Translation by the Ribosome"
  biological_processes:
  - preferred_term: Translation
    term:
      id: GO:0006412
      label: translation
  evidence:
  - reference: PMID:24336183
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The ribosome is one of the main antibiotic targets in the bacterial cell.
    explanation: >-
      Establishes the bacterial ribosome as the doxycycline (tetracycline) target,
      the step this node represents. Evidence source is OTHER as this is a review.
- name: Borrelial Peptidoglycan Cross-Linking (Beta-Lactam Target)
  description: >-
    Borrelia burgdorferi maintains its peptidoglycan cell wall by
    penicillin-binding protein (PBP) transpeptidase cross-linking. This essential,
    bacteria-specific reaction is the target of the amoxicillin and ceftriaxone
    used to treat Lyme disease; beta-lactam acylation of the PBP active site halts
    cross-linking and is bactericidal against disseminating spirochetes. CNS
    penetration of ceftriaxone is what extends this mechanism to neuroborreliosis.
  role: therapeutic_vulnerability
  conforms_to: "bacterial_cell_wall_synthesis_inhibition#Peptidoglycan Cross-Linking by Penicillin-Binding Proteins"
  biological_processes:
  - preferred_term: Peptidoglycan-Based Cell Wall Biogenesis
    term:
      id: GO:0009273
      label: peptidoglycan-based cell wall biogenesis
  evidence:
  - reference: PMID:22203377
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      although glycan chain polymerization occurs in the absence of
      transpeptidation (for example, in the presence of penicillin), efficient
      transpeptidation requires ongoing GTase reactions
    explanation: >-
      Establishes that beta-lactams act by blocking PBP transpeptidation, the
      cross-linking step this node represents. Evidence source is OTHER as this
      is a review article.
- name: Tick-Borne Transmission and Enzootic Cycle
  description: >
    Borrelia burgdorferi is maintained in an enzootic cycle between Ixodes ticks
    and small-mammal reservoirs such as the white-footed mouse; larval ticks
    acquire spirochetes by feeding on infected reservoirs and transmit them
    transstadially to the nymphal stage that bites humans. In the unfed tick
    midgut the spirochete expresses OspA (midgut adhesion) but not OspC. During
    the blood meal, host- and temperature-derived signals trigger a reciprocal
    antigenic switch in which OspA is downregulated and OspC is upregulated,
    accompanying spirochete migration from the midgut to the salivary glands and
    transmission into the vertebrate dermis; OspC expression peaks around 48 h of
    tick attachment and is required for early mammalian infectivity.
  evidence:
  - reference: PMID:10618120
    reference_title: "Temporal changes in outer surface proteins A and C of the lyme disease-associated spirochete, Borrelia burgdorferi, during the chain of infection in ticks and mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "B. burgdorferi expresses outer surface protein A (OspA) but not OspC when residing in the midgut of unfed ticks. However, after ticks feed on blood, some spirochetes stop making OspA and express OspC."
    explanation: Immunofluorescence of spirochetes in feeding Ixodes nymphs demonstrates the reciprocal OspA-to-OspC switch that accompanies transmission from tick to mammal.
  - reference: PMID:22230951
    reference_title: "Of ticks, mice and men: understanding the dual-host lifestyle of Lyme disease spirochaetes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "we integrate this large body of information into a cohesive picture of the molecular and cellular events that transpire as Lyme disease spirochaetes transit between their arthropod and vertebrate hosts during the enzootic cycle."
    explanation: Authoritative review frames B. burgdorferi pathogenesis around its dual-host transit between Ixodes ticks and vertebrate hosts during the enzootic cycle.
  biological_processes:
  - preferred_term: OspA/OspC antigenic switch
    term:
      id: GO:0010468
      label: regulation of gene expression
  - preferred_term: response to temperature stimulus
    term:
      id: GO:0009266
      label: response to temperature stimulus
  downstream:
  - target: Spirochete Invasion and Dissemination
    causal_link_type: DIRECT
    description: OspC-mediated transmission deposits infectious spirochetes in the host dermis, initiating local colonization and dissemination.
- name: Tick Saliva-Assisted Immune Evasion via Salp15-OspC
  description: >
    During transmission, Borrelia burgdorferi co-opts components of Ixodes tick
    saliva to establish infection at the bite site. The spirochete selectively
    enhances tick expression of the 15-kDa salivary protein Salp15, which binds
    the spirochetal surface lipoprotein OspC and coats the organism. Salp15
    (and its I. ricinus homologue Iric1) shields Borrelia from antibody-mediated
    killing and complement, giving the spirochete a marked infectivity advantage
    in the mammalian host; the bacterium thereby exploits a secreted arthropod
    protein to colonize the vertebrate dermis.
  evidence:
  - reference: PMID:16049492
    reference_title: "The Lyme disease agent exploits a tick protein to infect the mammalian host."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Salp15 was then shown to adhere to the spirochaete, both in vitro and in vivo, and specifically interacted with B. burgdorferi outer surface protein C. The binding of Salp15 protected B. burgdorferi from antibody-mediated killing in vitro and provided spirochaetes with a marked advantage when they were inoculated into naive mice"
    explanation: RNA-interference and infection experiments in Ixodes scapularis and mice show B. burgdorferi usurps the tick salivary protein Salp15, which binds OspC and protects the spirochete from antibody-mediated killing during transmission.
  - reference: PMID:33401196
    reference_title: "Strong interactions between Salp15 homologues from the tick I. ricinus and distinct types of the outer surface OspC protein from Borrelia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we show in this study that also Iric2 and Iric3 are capable of OspC binding with high affinity"
    explanation: Binding study demonstrates that, beyond the previously characterized Iric1, the I. ricinus Salp15 homologues Iric2 and Iric3 also bind Borrelia OspC with high affinity, reinforcing Salp15-family/OspC engagement as a conserved transmission-interface interaction.
  biological_processes:
  - preferred_term: Salp15-mediated protection from antibody-mediated killing
    term:
      id: GO:0042783
      label: symbiont-mediated evasion of host immune response
    modifier: INCREASED
  locations:
  - preferred_term: skin
    term:
      id: UBERON:0002097
      label: skin of body
  downstream:
  - target: Spirochete Invasion and Dissemination
    causal_link_type: DIRECT
    description: Salp15-coated spirochetes resist early humoral clearance at the bite site, enabling establishment of dermal infection and subsequent dissemination.
- name: Spirochete Invasion and Dissemination
  description: >
    Borrelia burgdorferi is transmitted through Ixodes tick bites. The spirochete
    disseminates from the skin through the bloodstream to multiple organ systems
    including joints, heart, and nervous system. Surface adhesins like BBK32 and
    decorin-binding proteins (DbpA/DbpB) facilitate tissue colonization, while
    OspC is upregulated at the tick-feeding/early-mammalian interface and is
    required for early infectivity.
  evidence:
  - reference: PMID:33669940
    reference_title: "Lyme Disease among Patients at an Ambulatory Unit in a Highly Endemic Country: Lithuania."
    supports: SUPPORT
    snippet: "The clinical manifestations of Lyme disease range from a localized infection, for example, erythema migrans (EM) to a disseminated neurological or rheumatological infection, cardiac involvement, or even chronic disease."
    explanation: Epidemiologic series shows Borrelia disseminates beyond skin to neurologic, rheumatologic, and cardiac sites.
  cell_types:
  - preferred_term: endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  biological_processes:
  - preferred_term: cell adhesion
    term:
      id: GO:0007155
      label: cell adhesion
  locations:
  - preferred_term: skin
    term:
      id: UBERON:0002097
      label: skin of body
  - preferred_term: blood
    term:
      id: UBERON:0000178
      label: blood
  downstream:
  - target: Inflammatory Response and Tissue Damage
    causal_link_type: DIRECT
    description: Disseminating spirochetes deliver lipoproteins and peptidoglycan that drive innate inflammation at colonized tissues.
  - target: Erythema Migrans
    causal_link_type: DIRECT
    description: Centrifugal migration of spirochetes outward through the dermis at the bite site produces the characteristic expanding erythema migrans rash of early localized infection.
- name: Complement Evasion via BBK32-Mediated C1r Inhibition
  description: >
    The Borrelia burgdorferi surface lipoprotein BBK32 binds C1r, the initiator
    protease of the classical complement pathway. This attenuates
    antibody-dependent complement activation and protects infectious Borrelia
    from complement-mediated killing in human serum.
  evidence:
  - reference: PMID:40705830
    reference_title: "BBK32 attenuates antibody-dependent complement-mediated killing of infectious Borreliella burgdorferi isolates."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "BBK32 binds to C1r, the initiator protease of the classical pathway of complement, and protects B. burgdorferi from complement-mediated killing following exposure to normal human serum."
    explanation: Functional in vitro evidence that BBK32 binds C1r and blocks classical-pathway complement killing of infectious Borrelia burgdorferi.
  biological_processes:
  - preferred_term: negative regulation of complement activation
    term:
      id: GO:0045916
      label: negative regulation of complement activation
    modifier: INCREASED
  downstream:
  - target: Spirochete Invasion and Dissemination
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Classical-pathway inhibition yields serum resistance, permitting spirochete survival during hematogenous dissemination.
    description: Blocking antibody-dependent complement killing allows surviving spirochetes to disseminate despite humoral immunity.
- name: Alternative Complement Pathway Evasion via Factor H Recruitment
  description: >
    Borrelia burgdorferi expresses complement regulator-acquiring surface proteins
    (CRASPs) such as CspA (CRASP-1), along with CspZ and OspE-family paralogs, that
    bind the host alternative-pathway regulators factor H and factor H-like protein 1
    (FH/FHL-1). Surface-bound FH/FHL-1 limits C3 deposition and membrane-attack-complex
    formation, conferring resistance to complement-mediated killing in human serum.
    This pathway complements the BBK32-mediated classical-pathway block.
  evidence:
  - reference: PMID:19451251
    reference_title: "CspA-mediated binding of human factor H inhibits complement deposition and confers serum resistance in Borrelia burgdorferi."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "the CspA-mediated binding of human FH confers serum resistance by directly inhibiting complement deposition on the surface of B. burgdorferi."
    explanation: A cspA knockout loses surface factor H binding and becomes serum-sensitive with enhanced C3/C6/C5b-9 deposition, demonstrating CspA-driven alternative-pathway evasion.
  biological_processes:
  - preferred_term: negative regulation of complement activation
    term:
      id: GO:0045916
      label: negative regulation of complement activation
    modifier: INCREASED
  downstream:
  - target: Spirochete Invasion and Dissemination
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Factor H recruitment produces serum resistance that enables spirochete survival in blood during dissemination.
    description: Alternative-pathway evasion sustains spirochete viability in serum, supporting hematogenous spread.
- name: Antigenic Variation via vlsE Gene Conversion
  description: >
    The vlsE locus undergoes gene conversion that diversifies Borrelia surface
    antigens, helping the pathogen evade host immune recognition during
    dissemination and persistent infection.
  evidence:
  - reference: PMID:39792948
    reference_title: "Breaking a barrier: In trans vlsE recombination and genetic manipulation of the native vlsE gene of the Lyme disease pathogen."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Borrelia burgdorferi, the Lyme disease pathogen, has evolved an intricate antigenic variation mechanism to evade the host immune response, enabling its dissemination, persistence, and pathogenicity."
    explanation: Mechanistic study of the vlsE locus confirms antigenic variation as the immune-evasion mechanism enabling B. burgdorferi persistence.
  biological_processes:
  - preferred_term: DNA recombination
    term:
      id: GO:0006310
      label: DNA recombination
    modifier: INCREASED
  downstream:
  - target: Spirochete Invasion and Dissemination
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Continuous surface-antigen diversification produces immune escape and persistent infection that sustain ongoing dissemination.
    description: Antigenic variation maintains an immune-evasive, persistent infection that supports continued tissue colonization.
- name: Host Lipid Scavenging and Membrane Biogenesis
  description: >
    Borrelia burgdorferi is a metabolically compromised spirochete (~1.5 Mbp
    genome) that cannot survive without host-derived lipids: it lacks de novo
    sterol synthesis and most lipid-biosynthetic capacity, requires exogenous
    cholesterol for growth and viability, and must scavenge lipids from the tick
    and vertebrate host to build and remodel its LPS-free, lipoprotein-rich cell
    envelope during the enzootic cycle. A multi-platform untargeted and targeted
    LC-MS/GC-MS lipidomic compendium detected more than 500 lipids in
    B. burgdorferi, the majority sourced from the environment through apparently
    discriminatory uptake (some species depleted 600-1500-fold during growth).
    The pathogen organizes neutral lipids — cholesteryl esters and triglycerides —
    into distinct intracellular foci (the first visual/molecular evidence of
    lipid-droplet-like storage in this minimal bacterium), and incorporates
    host sphingolipids and ceramides, with phosphatidylcholine established as a
    principal membrane constituent alongside cholesterol and cholesterol
    galactolipids (AcGal) that form cholesterol/sphingolipid lipid rafts.
    Unexpectedly, the spirochete also biosynthesizes predominantly eukaryotic
    lipids: four lysosomal bis(monoacylglycerol)phosphate (BMP) species (proposed
    roles in membrane plasticity/stress adaptation), phosphatidylglycerol and
    phosphatidylethanolamine, the plant galactolipid monogalactosyl diacylglycerol
    (MGDG; against which late-stage Lyme patients mount an antibody response), an
    acylated glycosylated phytosterol (acylhexosylcampesterol from scavenged
    campesterol), and the plant-type anionic sulfolipid sulfoquinovosyl
    diacylglycerol (SQDG). Structural-homology modeling against Arabidopsis SQD1/SQD2
    and heterologous E. coli reconstitution identified two interdependent B.
    burgdorferi enzymes, BB0444 and BB0454, as sufficient for SQDG biosynthesis
    (BB0454 also makes MGDG); homologs are broadly conserved across spirochetes
    and >30 Borrelia species. This "lipid chimera" strategy of intensive
    scavenging plus niche biosynthesis is essential for envelope integrity and
    persistence, nominating lipid acquisition, sulfolipid synthesis, and neutral-
    lipid storage as candidate antimicrobial targets.
  evidence:
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "belongs to a class of metabolically compromised bacteria that cannot survive without host-derived lipids"
    explanation: Lipidomic study establishes B. burgdorferi as a lipid auxotroph dependent on host-derived lipids for survival.
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The analysis detected more than 500 lipids in"
    explanation: Untargeted and targeted high-resolution mass spectrometry profiled a compendium of more than 500 lipids in the spirochete.
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "the bacterium selectively accumulates certain lipids while excluding others, suggesting discriminatory uptake. These include cholesteryl esters and triglycerides that are organized in foci within the pathogen"
    explanation: The spirochete shows discriminatory lipid uptake, concentrating cholesteryl esters and triglycerides into intracellular foci.
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "the pathogen also synthesizes predominantly eukaryotic lipids such as the lysosomal bis(monoacylglycerol)phosphate and the plant glycolipid sulfoquinovosyl diacylglycerol (SQDG)"
    explanation: Despite its metabolic limitations, B. burgdorferi retains biosynthesis of eukaryotic-type lipids (BMP and SQDG).
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "highlights lipid acquisition and synthesis pathways as potentially critical for pathogen survival"
    explanation: The authors nominate lipid acquisition and biosynthesis pathways as survival-critical and therefore as potential antimicrobial targets.
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The biosynthesis of the latter is carried out by enzymes that exhibit structural homology to plant oxidoreductases and galactosyltransferases"
    explanation: SQDG biosynthesis is carried out by spirochetal enzymes (identified in the full text as BB0444 and BB0454) structurally homologous to plant SQD1/SQD2, supporting a residual eukaryotic-type biosynthetic capacity.
  biological_processes:
  - preferred_term: host lipid acquisition
    term:
      id: GO:0006869
      label: lipid transport
    modifier: INCREASED
  - preferred_term: host cholesterol import
    term:
      id: GO:0070508
      label: cholesterol import
    modifier: INCREASED
  - preferred_term: cholesteryl ester and triglyceride storage in intracellular foci
    term:
      id: GO:0019915
      label: lipid storage
    modifier: INCREASED
  - preferred_term: sulfoquinovosyl diacylglycerol (SQDG) biosynthesis
    term:
      id: GO:0046506
      label: sulfolipid biosynthetic process
    modifier: INCREASED
  downstream:
  - target: Spirochete Invasion and Dissemination
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Host-lipid-dependent membrane biogenesis and cell-envelope remodeling sustain spirochete viability, enabling survival in host tissues during colonization and dissemination.
    description: Lipid scavenging and residual biosynthesis maintain the spirochete cell envelope, supporting survival and dissemination in the vertebrate host.
- name: Inflammatory Response and Tissue Damage
  description: >
    The host immune response to Borrelia antigens contributes to tissue damage.
    Spirochetal lipoproteins and peptidoglycan trigger robust innate immune
    activation with production of IL-6, IL-8, TNF, and chemokines (CCL3/CCL4).
    Persistent inflammation in joints may continue even after spirochete clearance.
  evidence:
  - reference: PMID:37407232
    reference_title: "Trauma-related Lyme arthritis."
    supports: SUPPORT
    snippet: "Aspiration of the left knee joint revealed a white cell count of 21.0×109/L (83% neutrophils) with negative Gram stain and culture. However, Lyme PCR was positive and accompanied by serologies consistent with Lyme arthritis."
    explanation: Lyme arthritis joint fluid shows marked neutrophilic inflammation despite negative cultures, consistent with immune-driven damage.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  biological_processes:
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
  locations:
  - preferred_term: synovial membrane
    term:
      id: UBERON:0002018
      label: synovial membrane of synovial joint
  downstream:
  - target: Arthralgia
    causal_link_type: DIRECT
    description: Inflammatory cytokines and immune-cell infiltration in and around joints produce the arthralgia that commonly precedes frank arthritis.
  - target: Arthritis
    causal_link_type: DIRECT
    description: Neutrophilic and lymphocytic synovial inflammation driven by Borrelia antigens produces the mono/oligoarticular inflammatory arthritis of Lyme disease.
  - target: Facial Palsy
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Perineural inflammation of the facial (cranial VII) nerve during early disseminated neuroborreliosis.
    description: Immune-mediated cranial neuritis of the facial nerve produces unilateral or bilateral facial palsy.
  - target: Atrioventricular Block
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Inflammatory infiltration of the myocardium and AV conduction system (Lyme carditis).
    description: Inflammation of the cardiac conduction system disrupts AV nodal conduction, producing variable-degree atrioventricular block.
  - target: Myelitis
    causal_link_type: DIRECT
    description: Inflammatory involvement of the spinal cord during acute neuroborreliosis produces myelitis.
  - target: Dementia (Reversible Neuroborreliosis)
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - CNS inflammation/encephalopathy from intrathecal Borrelia infection and immune response.
    description: CNS inflammation in neuroborreliosis produces a subcortical/reversible dementia syndrome that improves with antibiotic therapy.
  - target: Fatigue
    causal_link_type: DIRECT
    description: Systemic pro-inflammatory cytokines (IL-6, TNF) produce the profound constitutional fatigue seen across disease stages.
  - target: Autoimmune Activation after Persistent Infection
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Sustained antigen-driven inflammation is proposed to break self-tolerance in genetically predisposed hosts.
  - target: Post-Infectious Immune Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Tissue damage and inflammation from viable or nonviable spirochetes are a proposed driver of persistent post-treatment symptoms.
- name: Autoimmune Activation after Persistent Infection
  description: >
    Prolonged exposure of the host immune system to Borrelia antigens can drive
    post-infectious autoimmunity, with reported triggers of systemic autoimmune
    disease after Lyme borreliosis.
  evidence:
  - reference: PMID:34786243
    reference_title: "Lyme Borreliosis as a Trigger for Autoimmune Disease."
    supports: SUPPORT
    snippet: "long-term exposure of the host's immune system to spirochetes can contribute to the development of chronic autoimmune disease de novo."
    explanation: Case review links persistent Borrelia exposure to downstream autoimmune disease.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  biological_processes:
  - preferred_term: adaptive immune response
    term:
      id: GO:0002250
      label: adaptive immune response
  downstream:
  - target: Post-Infectious Immune Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Post-infectious autoimmune responses are one of the leading proposed mechanisms underlying persistent post-treatment symptoms.
  - target: Arthritis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - HLA-DRB1-restricted autoreactive T-cell responses sustaining synovial inflammation after spirochete clearance.
    description: Post-infectious autoimmunity drives antibiotic-refractory Lyme arthritis that persists despite eradication of viable spirochetes.
  - target: Bullous Skin Lesions
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Autoantibody-mediated subepidermal blistering (epidermolysis bullosa acquisita-like) triggered after Lyme infection.
    description: Post-infectious autoimmunity is a proposed trigger for the rare autoimmune blistering (EBA-like) skin lesions reported after Lyme disease.
- name: Post-Infectious Immune Dysregulation
  description: >
    In an estimated 10-20% of appropriately treated patients, symptoms such as
    fatigue, pain, and cognitive complaints persist for more than six months
    (post-treatment Lyme disease syndrome, PTLDS). The mechanism is not fully
    established; proposed drivers include an autoimmune response to spirochete-induced
    tissue damage and inflammation, broader immune dysfunction, and persistent
    viable or nonviable antigen. This node is a terminal post-infectious state
    rather than ongoing high-burden active infection in most cases.
  evidence:
  - reference: PMID:39161484
    reference_title: "What Makes It Tick: Exploring the Mechanisms of Post-treatment Lyme Disease Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We propose that ongoing PTLDS symptoms seem to be related to an autoimmune response to the tissue damage and inflammation caused by the viable or nonviable spirochete pathogen."
    explanation: IDSA-aligned clinical review proposes post-infectious autoimmune/immune-dysregulation mechanisms for persistent PTLDS symptoms.
  - reference: PMID:27358211
    reference_title: "CCL19 as a Chemokine Risk Factor for Posttreatment Lyme Disease Syndrome: a Prospective Clinical Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Receiver operating characteristic analysis identified a CCL19 cutoff of >111.67 pg/ml at 1 month following treatment completion to be 82% sensitive and 83% specific for later PTLDS."
    explanation: Prospective cohort identifies persistently elevated posttreatment levels of the T-cell chemokine CCL19 as an immunologic risk marker for PTLDS, supporting ongoing immune-driven dysregulation rather than resolved infection.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  - preferred_term: B cell
    term:
      id: CL:0000236
      label: B cell
  biological_processes:
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
  downstream:
  - target: Fatigue
    causal_link_type: DIRECT
    description: Persistent immune dysregulation underlies the chronic fatigue that is a core symptom of post-treatment Lyme disease syndrome.
agent_life_cycle:
  description: >-
    Borrelia burgdorferi is maintained in an enzootic cycle between Ixodes ticks
    and small-mammal reservoirs, notably the white-footed mouse. Larval ticks
    acquire spirochetes by feeding on infected reservoir hosts, carry them
    transstadially through the molt to the nymphal stage, and infected nymphs
    transmit spirochetes to new vertebrate hosts during a subsequent blood meal.
    Humans are incidental, dead-end hosts who do not contribute to maintenance of
    the cycle. The OspA-to-OspC antigenic switch coordinates these host
    transitions: OspA mediates midgut colonization in the unfed tick, whereas
    OspC is required for transmission to and early infection of the mammal.
  hosts:
  - preferred_term: White-footed mouse (small-mammal reservoir)
    role: reservoir host
    term:
      id: NCBITaxon:10041
      label: Peromyscus leucopus
  - preferred_term: Human (incidental dead-end host)
    role: incidental (dead-end) host
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  - preferred_term: Blacklegged tick (vector and maintenance host)
    role: vector host for transstadial maintenance and transmission
    term:
      id: NCBITaxon:6945
      label: Ixodes scapularis
  - preferred_term: Western blacklegged tick (vector host, western North America)
    role: vector host
    term:
      id: NCBITaxon:29930
      label: Ixodes pacificus
  - preferred_term: Castor bean tick (vector host, Europe)
    role: vector host
    term:
      id: NCBITaxon:34613
      label: Ixodes ricinus
  vectors:
  - Ixodes scapularis (blacklegged/deer tick, eastern North America)
  - Ixodes pacificus (western blacklegged tick, western North America)
  - Ixodes ricinus (castor bean tick, Europe)
  notes: >-
    This structured life-cycle view intentionally complements the
    "Tick-Borne Transmission and Enzootic Cycle" pathophysiology node: that node
    narrates the molecular OspA-to-OspC switch and its causal edges, whereas this
    block captures the host, vector, and stage facts in queryable form. The two
    deliberately share references (PMID:10618120, PMID:22230951).
  evidence:
  - reference: PMID:22230951
    reference_title: "Of ticks, mice and men: understanding the dual-host lifestyle of Lyme disease spirochaetes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "we integrate this large body of information into a cohesive picture of the molecular and cellular events that transpire as Lyme disease spirochaetes transit between their arthropod and vertebrate hosts during the enzootic cycle."
    explanation: Authoritative review frames B. burgdorferi biology around an obligate dual-host enzootic cycle alternating between Ixodes ticks and vertebrate hosts.
  life_cycle_stages:
  - name: Larval acquisition from reservoir host
    description: >-
      Uninfected larval (and nymphal) ticks acquire B. burgdorferi by taking a
      blood meal on an infected small-mammal reservoir such as the white-footed
      mouse; newly acquired spirochetes express OspA but not OspC.
    evidence:
    - reference: PMID:10618120
      reference_title: "Temporal changes in outer surface proteins A and C of the lyme disease-associated spirochete, Borrelia burgdorferi, during the chain of infection in ticks and mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "uninfected I. scapularis larvae and nymphs as they first acquired spirochetes from infected mice"
      explanation: Immunofluorescence of tick midguts shows uninfected larvae and nymphs acquiring spirochetes while feeding on infected mice, the acquisition step of the enzootic cycle.
  - name: Transstadial maintenance in the unfed tick midgut
    description: >-
      Spirochetes acquired at the larval stage persist through the molt into the
      nymph (transstadial passage) and colonize the unfed-tick midgut, where they
      express OspA but not OspC until the next blood meal.
    evidence:
    - reference: PMID:10618120
      reference_title: "Temporal changes in outer surface proteins A and C of the lyme disease-associated spirochete, Borrelia burgdorferi, during the chain of infection in ticks and mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "prior to feeding spirochetes in nymphs expressed OspA but not OspC"
      explanation: Infected nymphs (carrying spirochetes acquired as larvae) express OspA but not OspC before feeding, characterizing the transstadial midgut-maintenance stage.
  - name: Nymphal transmission to the mammalian host
    description: >-
      During the nymphal blood meal, the OspA-to-OspC switch accompanies
      spirochete migration to the salivary glands and transmission into the
      vertebrate dermis; OspC is required for transmission from tick to mammal.
    evidence:
    - reference: PMID:10618120
      reference_title: "Temporal changes in outer surface proteins A and C of the lyme disease-associated spirochete, Borrelia burgdorferi, during the chain of infection in ticks and mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "this surface protein is involved in transmission from tick to mammal but not from mammal to tick"
      explanation: Stage-specific OspC expression only in feeding infected ticks indicates OspC mediates the tick-to-mammal transmission stage of the cycle.
phenotypes:
- name: Erythema Migrans
  category: Dermatologic
  frequency: VERY_FREQUENT
  description: Characteristic expanding circular rash at the site of tick bite, often with central clearing (bull's-eye appearance). Present in 70-80% of cases.
  phenotype_term:
    preferred_term: Erythema migrans
    term:
      id: HP:0031180
      label: Erythema migrans
  evidence:
  - reference: PMID:33669940
    reference_title: "Lyme Disease among Patients at an Ambulatory Unit in a Highly Endemic Country: Lithuania."
    supports: SUPPORT
    snippet: "Results: In total, 1005 patients were enrolled with the following prevalence of clinical syndromes: erythema migrans (EM), 945 (94.02%); Lyme arthritis, 32 (3.18%); neuroborreliosis, 23 (2.28%); Lyme carditis, 4 (0.39%); and acrodermatitis, 1 (0.09%)."
    explanation: Large Lithuanian cohort confirms erythema migrans as the dominant presentation.
- name: Fatigue
  category: Constitutional
  frequency: FREQUENT
  description: Fatigue is a common systemic symptom of early Lyme disease and may persist in post-treatment Lyme disease syndrome.
  phenotype_term:
    preferred_term: Fatigue
    term:
      id: HP:0012378
      label: Fatigue
  evidence:
  - reference: PMID:8644761
    reference_title: "The clinical spectrum of early Lyme borreliosis in patients with culture-confirmed erythema migrans."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "including fatigue (54%), arthralgia (44%), myalgia"
    explanation: In a prospective cohort of 79 culture-confirmed erythema migrans patients, fatigue was the most common systemic symptom at 54%, which falls in the FREQUENT band (30-79%).
  - reference: PMID:33669940
    reference_title: "Lyme Disease among Patients at an Ambulatory Unit in a Highly Endemic Country: Lithuania."
    supports: PARTIAL
    snippet: "Clinical symptoms were as follows: arthralgia (33.2%), general weakness (19%), head pain (13.1%), myalgia (11.2%), fever (6.2%), joint swelling (5.9%), head dizziness (5.1%), nervus facialis neuropathy (2.4%), and radiculitis (2.0%)."
    explanation: An ambulatory cohort reports general weakness at 19% (OCCASIONAL band); retained as a secondary, lower estimate that reflects cohort/definition variability.
- name: Arthralgia
  category: Musculoskeletal
  frequency: FREQUENT
  description: Joint pain, particularly affecting large joints such as the knee, commonly precedes frank arthritis.
  phenotype_term:
    preferred_term: Arthralgia
    term:
      id: HP:0002829
      label: Arthralgia
  evidence:
  - reference: PMID:33669940
    reference_title: "Lyme Disease among Patients at an Ambulatory Unit in a Highly Endemic Country: Lithuania."
    supports: SUPPORT
    snippet: "Clinical symptoms were as follows: arthralgia (33.2%), general weakness (19%), head pain (13.1%), myalgia (11.2%), fever (6.2%), joint swelling (5.9%), head dizziness (5.1%), nervus facialis neuropathy (2.4%), and radiculitis (2.0%)."
    explanation: Arthralgia was reported in one-third of patients in a large endemic cohort.
- name: Facial Palsy
  category: Neurological
  frequency: OCCASIONAL
  description: Unilateral or bilateral facial nerve palsy (Bell's palsy) in early disseminated disease, occurring in approximately 5% of untreated patients.
  phenotype_term:
    preferred_term: Facial palsy
    term:
      id: HP:0010628
      label: Facial palsy
  evidence:
  - reference: PMID:33669940
    reference_title: "Lyme Disease among Patients at an Ambulatory Unit in a Highly Endemic Country: Lithuania."
    supports: SUPPORT
    snippet: "The main symptoms were the following: nervus facialis neuropathy (47.8%), myalgia (39%), head pain (26%), and radiculitis (21%)."
    explanation: Neuroborreliosis cases frequently manifested facial nerve palsy.
- name: Arthritis
  category: Musculoskeletal
  frequency: FREQUENT
  description: Inflammatory arthritis, typically monoarticular or oligoarticular, affecting large joints especially the knee. Occurs in approximately 60% of untreated patients.
  phenotype_term:
    preferred_term: Arthritis
    term:
      id: HP:0001369
      label: Arthritis
  evidence:
  - reference: PMID:33669940
    reference_title: "Lyme Disease among Patients at an Ambulatory Unit in a Highly Endemic Country: Lithuania."
    supports: SUPPORT
    snippet: "Lyme arthritis mainly manifested among middle-aged women as an oligoarthritis, mostly affecting the knee joint."
    explanation: Cohort study documents oligoarticular knee-predominant Lyme arthritis.
- name: Atrioventricular Block
  category: Cardiac
  frequency: OCCASIONAL
  description: Cardiac involvement including AV block (first, second, or third degree) and myocarditis. Lyme carditis occurs in 1-5% of untreated patients.
  phenotype_term:
    preferred_term: Atrioventricular block
    term:
      id: HP:0001678
      label: Atrioventricular block
  evidence:
  - reference: PMID:37234726
    reference_title: "Lyme disease presenting as complete heart block in a young man: Case report and review of pathogenesis."
    supports: SUPPORT
    snippet: "the most common clinical manifestation is AV block, which can be acute in onset and can rapidly progress to complete heart block."
    explanation: Case report and review emphasize AV block as the hallmark of Lyme carditis.
- name: Dementia (Reversible Neuroborreliosis)
  category: Neurological
  frequency: VERY_RARE
  description: Subcortical or reversible dementia presentations of neuroborreliosis that improve with antibiotic therapy.
  phenotype_term:
    preferred_term: Dementia
    term:
      id: HP:0000726
      label: Dementia
  evidence:
  - reference: PMID:30046879
    reference_title: "Secondary dementia due to Lyme neuroborreliosis."
    supports: SUPPORT
    snippet: "Dementia-like syndromes are rare manifestations of Lyme neuroborreliosis... The response to 2-4 weeks of antibiotic treatment with ceftriaxone was excellent."
    explanation: Review of definite neuroborreliosis cases shows dementia syndromes resolving after ceftriaxone.
  - reference: PMID:36740841
    reference_title: "A Case of Reversible Dementia? Dementia vs Delirium in Lyme Disease."
    supports: SUPPORT
    snippet: "Lyme disease is an uncommon cause of reversible dementia... the brilliant clinical improvement after the appropriate antimicrobial therapy is strongly suggestive for a diagnosis of neuroborreliosis."
    explanation: Geriatric case of reversible dementia with marked improvement after antimicrobial therapy.
- name: Myelitis
  category: Neurological
  frequency: VERY_RARE
  description: Inflammatory spinal cord involvement as a rare manifestation of acute neuroborreliosis, sometimes with mild clinical symptoms despite marked MRI edema.
  phenotype_term:
    preferred_term: Myelitis
    term:
      id: HP:0012486
      label: Myelitis
  evidence:
  - reference: PMID:33082765
    reference_title: "Isolated Cervical Myelitis in Lyme Disease: A Rare Manifestation of Acute Neuroborreliosis."
    supports: SUPPORT
    snippet: "We report a case of acute neuroborreliosis that manifested as extended isolated cervical myelitis."
    explanation: Case report confirms Lyme-associated cervical myelitis with CSF pleocytosis and intrathecal Borrelia antibodies.
- name: Bullous Skin Lesions
  category: Dermatologic
  frequency: VERY_RARE
  description: Autoimmune blistering lesions (epidermolysis bullosa acquisita-like) following Lyme infection; reported after atypical erythema migrans.
  phenotype_term:
    preferred_term: Subepidermal blistering
    term:
      id: HP:0033804
      label: Subepidermal blistering
  evidence:
  - reference: PMID:41133080
    reference_title: "Lyme Disease Causing Complex Bullous Lesions: A Case Report."
    supports: SUPPORT
    snippet: "developed acquired epidermolysis bullosa (EBA) following an LD diagnosis. Initially, the patient presented with atypical erythema migrans, which later evolved into multiple bullous lesions"
    explanation: Case report documents bullous lesions evolving after Lyme disease.
biochemical:
- name: Anti-Borrelia Antibodies (IgM/IgG)
  presence: Detected
  context: Two-tier testing with ELISA screening and Western blot confirmation; antibodies may take 2-4 weeks to develop
  evidence:
  - reference: PMID:38651851
    reference_title: "Skin Changes in Suspected Lyme Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IgM and IgG specific for Borrelia burgdorferi was also performed: IgG was borderline, whereas IgM was positive at 218 U/mL."
    explanation: Case demonstrates serological IgM/IgG detection against Borrelia burgdorferi as part of Lyme disease diagnosis.
- name: Elevated ESR/CRP
  presence: Elevated
  context: Markers of systemic inflammation, especially in disseminated disease
- name: CSF Pleocytosis
  presence: Elevated
  context: In neuroborreliosis, lymphocytic pleocytosis with elevated protein and intrathecal antibody production
  evidence:
  - reference: PMID:42001681
    reference_title: "Metabolomic insights into Lyme neuroborreliosis: Exploring cerebrospinal fluid for diagnostic clues."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "accurate diagnosis of LNB requires cerebrospinal fluid (CSF) analysis, demonstrating pleocytosis and intrathecal synthesis of Bbsl-specific antibodies."
    explanation: Lyme neuroborreliosis diagnosis is anchored on demonstrated CSF pleocytosis and intrathecal Bbsl-specific antibody synthesis.
genetic:
- name: HLA-DRB1 Susceptibility Alleles
  association: Susceptibility
  notes: European antibiotic-refractory Lyme arthritis cohorts show disease-specific T helper responses linked predominantly to HLA-DRB1*11 or *13 alleles, distinct from alleles reported in North American cohorts.
  evidence:
  - reference: PMID:39225104
    reference_title: "Wider recognition and greater understanding of postinfectious, antibiotic-refractory Lyme arthritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the TCR-β motif was linked predominantly to HLA-DRB1*11 or 13 alleles, which differed from alleles in patients from North America."
    explanation: Editorial highlights HLA-DRB1 allele linkage to T cell receptor motifs that distinguish antibiotic-refractory Lyme arthritis from other rheumatic diseases.
environmental:
- name: Tick Exposure
  notes: Ixodes scapularis (deer tick) in eastern North America, I. pacificus in western North America, I. ricinus in Europe
- name: Geographic Location
  notes: Endemic areas include northeastern and upper midwestern United States, and parts of Europe and Asia
- name: Seasonal Exposure
  notes: Peak transmission during late spring and summer months (May-August) when nymphal ticks are active
  evidence:
  - reference: PMID:37075475
    reference_title: "Seasonal activity patterns of host-seeking Ixodes scapularis (Acari: Ixodidae) in Minnesota, 2015-2017."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Nymphs were most active from May through August, with continuing low-level activity in October, and peak activity most commonly observed in June. The observed nymphal peak corresponded with the typical peak in reported human Lyme disease and anaplasmosis cases."
    explanation: Field surveillance of Ixodes scapularis confirms that peak nymphal host-seeking from May–August aligns with the seasonal peak of human Lyme disease cases.
- name: Outdoor Activities
  notes: Risk factors include hiking, camping, gardening, and activities in wooded or grassy areas
  evidence:
  - reference: PMID:37075475
    reference_title: "Seasonal activity patterns of host-seeking Ixodes scapularis (Acari: Ixodidae) in Minnesota, 2015-2017."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "These findings are consistent with previous studies from the Upper Midwest and highlight a risk of human exposure to I. scapularis at least from April through November."
    explanation: Seasonal tick surveillance highlights prolonged human exposure risk in woodland habitats during months when outdoor activity can lead to Ixodes contact.
- name: Non-Ixodes Tick Exposure
  notes: Rare reports of dog tick (Rhipicephalus) transmission in India; underscores need to consider atypical vectors in endemic settings
  evidence:
  - reference: PMID:36352974
    reference_title: "Dog tick (Rhipecephalus) causing Lyme disease in an adult human."
    supports: SUPPORT
    snippet: "we present the case of Lyme's disease in an adult male with dog tick, Rhipecephalus as a vector."
    explanation: Case report documents Lyme transmission by Rhipicephalus dog tick, highlighting atypical vector risk.
diagnosis:
- name: Serologic testing
  description: >-
    Diagnosis rests primarily on clinical evaluation, with serology reserved
    for suspected disseminated disease; testing is not indicated in early
    localized erythema migrans, where sensitivity is low and clinical
    diagnosis is reliable.
  diagnosis_term:
    preferred_term: serology testing
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  results: Two-tiered serologic result supporting suspected disseminated Lyme borreliosis.
  evidence:
  - reference: PMID:41314468
    reference_title: "Guidelines for Lyme borreliosis: Diagnostic strategies."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Serology is recommended only in suspected disseminated LB, characterized by compatible clinical signs and history of tick exposure."
    explanation: The Lyme borreliosis diagnostic-strategy guideline restricts serologic testing to suspected disseminated disease with compatible clinical signs and tick exposure.
  - reference: PMID:41314468
    reference_title: "Guidelines for Lyme borreliosis: Diagnostic strategies."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "In early localized disease such as erythema migrans, laboratory testing is unnecessary due to low sensitivity and the reliability of clinical diagnosis."
    explanation: The same guideline advises against laboratory testing in early localized erythema migrans, where sensitivity is low and clinical diagnosis is reliable.

treatments:
- name: Oral Doxycycline
  description: >
    First-line treatment for early localized and early disseminated Lyme disease
    in adults. Typical dose is 100mg twice daily for 10-21 days. Also provides
    prophylaxis for tick bites in endemic areas.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: doxycycline
      term:
        id: CHEBI:50845
        label: doxycycline
  evidence:
  - reference: PMID:17029130
    reference_title: "The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America."
    supports: SUPPORT
    snippet: "Tables list the doses and durations of antimicrobial therapy recommended for treatment and prevention of Lyme disease"
    explanation: IDSA guidelines provide evidence-based antibiotic treatment recommendations for Lyme disease.
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: Spirochete Invasion and Dissemination
    treatment_effect: INHIBITS
    description: Doxycycline is bactericidal against Borrelia burgdorferi, eradicating disseminating spirochetes and arresting the causal chain upstream of tissue inflammation and downstream manifestations.
  - target: Borrelial Ribosomal Translation (Doxycycline Target)
    treatment_effect: INHIBITS
    description: Doxycycline binds the 30S ribosome and arrests borrelial protein synthesis.
  target_phenotypes:
  - preferred_term: Erythema migrans
    term:
      id: HP:0031180
      label: Erythema migrans
- name: Oral Amoxicillin
  description: >
    Alternative first-line agent for early Lyme disease, preferred in children
    under 8 years and pregnant women. Typical dose is 500mg three times daily.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: amoxicillin
      term:
        id: CHEBI:2676
        label: amoxicillin
  evidence:
  - reference: PMID:17176487
    reference_title: "Lyme disease in pregnancy: case report and review of the literature."
    supports: SUPPORT
    snippet: "We describe a favorable outcome in a 42-year-old woman who developed Lyme disease in the third trimester and was treated with a full course of oral amoxicillin."
    explanation: Case report in pregnancy shows successful treatment with amoxicillin.
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: Spirochete Invasion and Dissemination
    treatment_effect: INHIBITS
    description: Amoxicillin is bactericidal against Borrelia burgdorferi, clearing disseminating spirochetes in early Lyme disease.
  - target: Borrelial Peptidoglycan Cross-Linking (Beta-Lactam Target)
    treatment_effect: INHIBITS
    description: Amoxicillin acylates the borrelial PBP transpeptidase, blocking peptidoglycan cross-linking.
  target_phenotypes:
  - preferred_term: Erythema migrans
    term:
      id: HP:0031180
      label: Erythema migrans
- name: Intravenous Ceftriaxone
  description: >
    Recommended for neurological Lyme disease (neuroborreliosis), Lyme carditis
    with high-degree AV block, and some cases of Lyme arthritis. Duration
    typically 14-28 days.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: ceftriaxone
      term:
        id: CHEBI:29007
        label: ceftriaxone
  evidence:
  - reference: PMID:37692616
    reference_title: "Lyme Disease Presenting With Interesting Neurological Features of Weakness and Hyporeflexia: A Case Report."
    supports: SUPPORT
    snippet: "The patient's symptoms resolved quickly with a four-day inpatient course of IV ceftriaxone followed by 10 days of oral doxycycline."
    explanation: Neuroborreliosis case improved with intravenous ceftriaxone then doxycycline.
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: Spirochete Invasion and Dissemination
    treatment_effect: INHIBITS
    description: Ceftriaxone penetrates the CNS and is bactericidal against Borrelia burgdorferi, clearing spirochetes disseminated to the nervous system, heart, and joints.
  - target: Borrelial Peptidoglycan Cross-Linking (Beta-Lactam Target)
    treatment_effect: INHIBITS
    description: Ceftriaxone acylates the borrelial PBP transpeptidase, blocking peptidoglycan cross-linking; its CNS penetration extends this to neuroborreliosis.
  target_phenotypes:
  - preferred_term: Facial palsy
    term:
      id: HP:0010628
      label: Facial palsy
  - preferred_term: Atrioventricular block
    term:
      id: HP:0001678
      label: Atrioventricular block
  - preferred_term: Myelitis
    term:
      id: HP:0012486
      label: Myelitis
  - preferred_term: Dementia
    term:
      id: HP:0000726
      label: Dementia
  - preferred_term: Arthritis
    term:
      id: HP:0001369
      label: Arthritis
differential_diagnoses:
- name: Southern Tick-Associated Rash Illness (STARI)
  disease_term:
    preferred_term: Southern Tick-Associated Rash Illness
    term:
      id: MONDO:0025294
      label: tick-borne infectious disease
  description: Lone star tick-associated erythema migrans–like rash without Borrelia burgdorferi infection.
  distinguishing_features:
  - Occurs after Amblyomma americanum bite in southeastern/south-central US; Borrelia testing negative.
  - Typically lacks systemic neurologic or cardiac involvement seen in disseminated Lyme.
  evidence:
  - reference: PMID:40788480
    reference_title: "Could alpha-gal syndrome be the cause of southern tick-associated rash illness (STARI)? : A simple study could answer that question."
    supports: SUPPORT
    snippet: "southern tick-associated rash illness (STARI)"
    explanation: Highlights STARI as a distinct erythema migrans–like illness linked to lone star tick bites.
- name: Cellulitis
  disease_term:
    preferred_term: cellulitis
    term:
      id: MONDO:0005230
      label: cellulitis
  description: Bacterial skin infection that can mimic early erythema migrans.
  distinguishing_features:
  - Painful, warm, expanding erythema often with fever.
  - No central clearing.
  - Responds rapidly to anti-staphylococcal/streptococcal therapy.
  evidence:
  - reference: PMID:26437159
    reference_title: "Vesicular erythema migrans: an atypical and easily misdiagnosed form of Lyme disease."
    supports: SUPPORT
    snippet: "atypical vesicular features... resulted in multiple misdiagnoses and delayed treatment"
    explanation: Atypical erythema migrans presentations can be misdiagnosed as bacterial cellulitis.
- name: Septic Arthritis
  disease_term:
    preferred_term: infective arthritis
    term:
      id: MONDO:0042485
      label: infective arthritis
  description: Acute bacterial arthritis of large joints.
  distinguishing_features:
  - Very high synovial WBC with positive Gram stain/culture.
  - Lacks migratory arthralgias and Borrelia serology.
  - Requires urgent drainage.
  evidence:
  - reference: PMID:24028811
    reference_title: "[Lyme arthritis in children: a diagnostic trap]."
    supports: SUPPORT
    snippet: "clinical and biological picture often resembles that of septic arthritis"
    explanation: Pediatric Lyme arthritis cases can initially be confused with septic arthritis.
- name: Rheumatoid Arthritis
  disease_term:
    preferred_term: rheumatoid arthritis
    term:
      id: MONDO:0008383
      label: rheumatoid arthritis
  description: Chronic symmetric inflammatory polyarthritis.
  distinguishing_features:
  - Small-joint symmetric involvement with RF/anti-CCP positivity.
  - No tick exposure history or erythema migrans.
  - Nodules and erosions on imaging.
  evidence:
  - reference: PMID:24028811
    reference_title: "[Lyme arthritis in children: a diagnostic trap]."
    supports: SUPPORT
    snippet: "clinical and biological picture often resembles that of septic arthritis and juvenile rheumatoid arthritis"
    explanation: Lyme arthritis may mimic rheumatoid patterns, prompting serologic differentiation.
- name: Viral Encephalitis
  disease_term:
    preferred_term: viral encephalitis
    term:
      id: MONDO:0006009
      label: viral encephalitis
  description: CNS infection causing encephalopathy that can overlap with neuroborreliosis symptoms.
  distinguishing_features:
  - CSF PCR panels for HSV/VZV/arboviruses.
  - Absent Borrelia intrathecal antibodies.
  - Often acute febrile onset.
  evidence:
  - reference: PMID:29848409
    reference_title: "Serologic Evidence of Tick-Borne Encephalitis Virus Infection in a Patient with Suspected Lyme Disease in Japan."
    supports: SUPPORT
    snippet: "Two serum samples from one patient showed neutralizing antibodies against TBE virus."
    explanation: Tick-borne encephalitis virus infection was found in a patient initially suspected of Lyme, illustrating viral encephalitis as a key differential.
- name: Multiple Sclerosis and Other Demyelinating Myelopathies
  disease_term:
    preferred_term: multiple sclerosis
    term:
      id: MONDO:0005301
      label: multiple sclerosis
  description: Demyelinating CNS disease that can mimic neuroborreliosis with cord lesions.
  distinguishing_features:
  - Oligoclonal bands without intrathecal Borrelia antibodies.
  - Typical MS lesion distribution.
  - Relapsing course without tick exposure.
  evidence:
  - reference: PMID:34861197
    reference_title: "Mistaken Identity: Many Diagnoses are Frequently Misattributed to Lyme Disease."
    supports: SUPPORT
    snippet: "Examples... newly diagnosed included multiple sclerosis"
    explanation: Cohort of presumed Lyme referrals identified multiple sclerosis as a frequent alternate diagnosis.
- name: Viral Myocarditis/Other Causes of AV Block
  disease_term:
    preferred_term: myocarditis
    term:
      id: MONDO:0004496
      label: myocarditis
  description: Cardiac conduction disease from viral myocarditis or idiopathic fibrosis.
  distinguishing_features:
  - Elevated cardiac biomarkers and viral serologies.
  - Absence of erythema migrans or Lyme serology.
  - Persistent AV block without rapid reversal on antibiotics.
  evidence:
  - reference: PMID:40385752
    reference_title: "Dengue Fever-Induced Complete Heart Block (Cardiac Dengue) Requiring Permanent Pacemaker Implantation in a 53-Year-Old Man: A Case Report."
    supports: SUPPORT
    snippet: "Comprehensive investigations excluded other bradyarrhythmia causes, such as Lyme disease, sarcoidosis, and myocarditis"
    explanation: Case of dengue-related complete heart block underscores non-Lyme infectious causes of advanced AV block.
clinical_trials:
- name: NCT03769194
  phase: PHASE_II
  status: COMPLETED
  description: Randomized, controlled, observer-blind Phase 2 study evaluating immunogenicity and safety of VLA15, a multivalent recombinant OspA-based Lyme borreliosis vaccine candidate in healthy adults aged 18-65 years. Participants received 3 immunizations at monthly intervals.
  target_phenotypes:
  - preferred_term: Erythema migrans
    term:
      id: HP:0031180
      label: Erythema migrans
  evidence:
  - reference: clinicaltrials:NCT03769194
    reference_title: "VLA15 Phase 2 Lyme borreliosis vaccine immunogenicity and safety study (NCT03769194)"
    supports: SUPPORT
    snippet: "The study was investigated 3 doses of a multivalent OspA (Outer Surface Protein A) based Lyme vaccine (VLA15) in healthy adults aged 18 to 65 years of age. Study participants received 3 immunizations of the vaccine at a monthly interval."
    explanation: This Phase 2 trial evaluates VLA15, a preventive vaccine targeting OspA surface protein, offering evidence for active immunization against Lyme borreliosis.
- name: NCT06785402
  phase: PHASE_II
  status: RECRUITING
  description: Randomized, double-blind, placebo-controlled Phase 1/2 trial evaluating pulse-dosed intravenous ceftriaxone for Post-Treatment Lyme Disease Syndrome (PTLDS). Investigates whether periodic high-dose antibiotic therapy can eliminate persistent Borrelia burgdorferi in patients with persistent symptoms.
  target_phenotypes:
  - preferred_term: Fatigue
    term:
      id: HP:0012378
      label: Fatigue
  - preferred_term: Arthralgia
    term:
      id: HP:0002829
      label: Arthralgia
  evidence:
  - reference: clinicaltrials:NCT06785402
    reference_title: "Pulse-Dosed IV Ceftriaxone for Post-Treatment Lyme Disease Syndrome (NCT06785402)"
    supports: SUPPORT
    snippet: "Lyme disease is a public health crisis in the US. It is estimated that over 400,000 cases occur every year with 10-20% of those infected going on to develop Post-Treatment Lyme disease Syndrome (PTLDS). The goal of this study is to investigate if giving Ceftriaxone every 5 days for about 6 weeks kills the organism that produces persistent Lyme infection."
    explanation: This Phase 1/2 trial directly addresses post-treatment Lyme disease syndrome with a novel pulse-dosing regimen, providing clinical evidence for managing antibiotic-refractory cases.
- name: NCT03584919
  phase: NOT_APPLICABLE
  status: COMPLETED
  description: European prospective clinical trial comparing doxycycline and cefuroxime axetil for treatment of erythema migrans in adult patients. Participants were evaluated at baseline, 14 days, and 2, 6, and 12 months post-enrollment to assess treatment efficacy and long-term outcomes.
  target_phenotypes:
  - preferred_term: Erythema migrans
    term:
      id: HP:0031180
      label: Erythema migrans
  evidence:
  - reference: clinicaltrials:NCT03584919
    reference_title: "Doxycycline versus Cefuroxime Axetil for Adult Erythema Migrans (NCT03584919)"
    supports: SUPPORT
    snippet: "A European, prospective clinical trial in which doxycycline and cefuroxime axetil were compared in the treatment of adult patients with erythema migrans included a control group to address this question. Evaluations of patients were conducted at baseline, 14 days and 2, 6, and 12 months after enrollment."
    explanation: This comparative trial evaluates two oral antibiotics for early Lyme disease, providing evidence for treatment options and long-term symptom outcomes in erythema migrans patients.
datasets:
- accession: DOI:10.64898/2026.05.22.727245
  title: A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism
  description: >
    Untargeted and targeted high-resolution mass-spectrometry lipidomics of the
    Lyme disease spirochete Borrelia burgdorferi, profiling more than 500 membrane
    and storage lipids and tracing their host/environmental origin versus residual
    de novo biosynthesis. Identifies discriminatory lipid uptake, cholesteryl
    ester and triglyceride accumulation in intracellular foci, and biosynthesis of
    eukaryotic-type lipids (bis(monoacylglycerol)phosphate and sulfoquinovosyl
    diacylglycerol), nominating lipid acquisition and synthesis pathways as
    survival-critical antimicrobial targets.
  organism:
    preferred_term: Borrelia burgdorferi
    term:
      id: NCBITaxon:139
      label: Borreliella burgdorferi
  data_type: METABOLOMICS
  conditions:
  - In vitro-cultured Borrelia burgdorferi (BSK-II medium with 6% rabbit serum)
  platform: Multi-platform LC-MS (Orbitrap, triple quadrupole, quadrupole time-of-flight) and GC-MS untargeted and targeted lipidomics
  publication: PMID:42239376
  findings:
  - statement: Borrelia burgdorferi is a lipid auxotroph that cannot survive without host-derived lipids.
    supporting_text: "belongs to a class of metabolically compromised bacteria that cannot survive without host-derived lipids"
  - statement: More than 500 lipids were detected, the majority sourced from the environment via discriminatory uptake.
    supporting_text: "The analysis detected more than 500 lipids in"
  - statement: Neutral lipids (cholesteryl esters and triglycerides) are organized into distinct intracellular foci — the first evidence of lipid-droplet-like storage in this minimal bacterium.
    supporting_text: "neutral lipids are organized into distinct intracellular foci"
  - statement: Phosphatidylcholine is a principal membrane constituent alongside cholesterol and cholesterol galactolipids.
    supporting_text: "phosphatidylcholine as one of the principal membrane constituents alongside cholesterol and cholesterol galactolipids"
  - statement: Four lysosomal bis(monoacylglycerol)phosphate (BMP) species, absent from the medium, are biosynthesized by the pathogen.
    supporting_text: "We identified four BMPs in B. burgdorferi that were entirely absent from the CM"
  - statement: The interdependent enzymes BB0444 and BB0454 are sufficient for biosynthesis of the plant-type sulfolipid SQDG (confirmed by heterologous expression in E. coli).
    supporting_text: "we discovered two enzymes, BB0444 and BB0454, in B. burgdorferi that are sufficient for the synthesis of SQDG"
  evidence:
  - reference: PMID:42239376
    reference_title: "A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we used a suite of untargeted and targeted high-resolution mass spectrometry methods to reveal a complex lipid profile of the pathogen and to identify the origin of its lipids"
    explanation: Describes the untargeted and targeted high-resolution MS lipidomics workflow that generated this dataset.
  notes: >-
    Preprint dataset (bioRxiv DOI:10.64898/2026.05.22.727245; also PMID:42239376 /
    PMC13228262). Lipidomics is recorded under the METABOLOMICS data_type because
    the schema has no dedicated lipidomics value. The evidence snippets are exact
    quotes from the published abstract; the additional `findings` supporting_text
    quotes are drawn from the full-text preprint PDF.

📚

References & Deep Research

Deep Research

2

Disorder ▸

Disorder

Name: Lyme Disease
Category: Infectious
Existing deep-research providers: falcon
Existing evidence reference count in YAML: 27

Key Pathophysiology Nodes

Spirochete Invasion and Dissemination
Autoimmune Activation after Persistent Infection
Inflammatory Response and Tissue Damage

Citation Inventory (for evidence mapping)

(none extracted)

Falcon ▸

Disease Pathophysiology Research Report

Edison Scientific Literature 11 citations 2026-01-08T21:51:08.760682

Disease Pathophysiology Research Report

Target Disease - Disease Name: Lyme disease (Borreliella/Borrelia burgdorferi infection) - MONDO ID: [not provided] - Category: Infectious

Pathophysiology description (current understanding) Lyme disease pathophysiology reflects a sequence of vector-mediated inoculation, early dermal colonization, hematogenous dissemination with vascular-interstitial transitions, and tissue-specific persistence, enabled by a large repertoire of outer-surface lipoproteins that coordinate adhesion, immune evasion (especially complement inhibition), and antigenic variation. The host response spans robust innate and adaptive activation with characteristic cytokine/chemokine patterns and, in subsets, post-infectious immune dysregulation (including autoimmunity) that underlies antibiotic-refractory manifestations such as post-infectious Lyme arthritis and post-treatment Lyme disease syndrome (PTLDS). Mechanistic highlights from recent literature (2023–2024 priority; later data included when highly pertinent) are summarized below with genes/proteins and processes mapped to ontology terms.

1) Core pathophysiology - Immune evasion via complement inhibition and antigenic variation • Classical pathway inhibition: The multifunctional surface lipoprotein BBK32 binds C1r (initiator protease of the classical pathway) and reduces C4 deposition, attenuating antibody-dependent complement-mediated killing while simultaneously retaining fibronectin adhesion functionality (mechanistic evidence and imaging/flow cytometry) (https://doi.org/10.1371/journal.ppat.1013361; PLOS Pathogens, 2025) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). • Alternative pathway inhibition: B. burgdorferi expresses a suite of complement regulator–acquiring surface proteins (CRASPs; e.g., CspA, CspZ, OspE family) that bind factor H or FHL-1 to block alternative pathway activation and membrane attack complex formation; variant-specific factor H binding contributes to host tropism and transmission biology (review synthesis) (farooq2025osteoimmunologicalcharacterizationof pages 42-44, powellpierce2025bbk32attenuatesantibodydependent pages 19-20). • Antigenic variation: The vlsE locus undergoes continuous segmental recombination with ~15 silent cassettes during mammalian infection, driving immune escape of surface antigenicity (farooq2025osteoimmunologicalcharacterizationof pages 42-44).

Dissemination and tissue adhesion • BBK32–fibronectin binding supports vascular interactions and, together with glycosaminoglycan (GAG) binding, facilitates endothelial adhesion and extravasation; BBK32’s dual complement- and fibronectin-binding functionalities allow parallel immune evasion and tissue dissemination (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). • Decorin-binding proteins (DbpA/DbpB) promote ECM engagement and tissue tropism; computational/biophysical evidence further implicates integrin interactions and plasminogen activation in trans-endothelial migration (nasrallah2023screeninginsilico pages 8-14). • OspC is upregulated at tick feeding/early mammalian infection and is required for infectivity; OspC–Salp15 interactions contribute to immune evasion at the vector–host interface (farooq2025osteoimmunologicalcharacterizationof pages 42-44).
Inflammatory drivers and persistence factors • Spirochetal peptidoglycan (localized to the periplasmic space with periplasmic flagella) is a potent innate stimulus; in comparative contexts B. burgdorferi evokes higher IL-6, IL-8, IL-10, CCL3/4, and TNF responses than some Eurasian species (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). Motility up to ~4.25 μm/s and chemotaxis toward host carbohydrates (e.g., N-acetylglucosamine) facilitate tissue spread and immune engagement (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). • Neuroinflammatory cytokines (e.g., IL-6) are implicated in disease models; host IL-6 modulation has been linked to altered neuroinflammatory readouts in preclinical systems (farooq2025osteoimmunologicalcharacterizationof pages 42-44).
Post-infectious immune dysregulation • PTLDS occurs in an estimated 10–20% of appropriately treated patients and has been hypothesized to involve immune dysfunction, autoimmunity, neuroinflammation, and/or persistent antigen; transcriptomic studies report hundreds of genes differentially expressed months after therapy. Clinical evidence also links higher CCL19 at 1 month (e.g., >~112 pg/mL) with a markedly increased odds of PTLDS at 6–12 months (review synthesis) (Cureus, 2024; https://doi.org/10.7759/cureus.64987) (wester2024whatmakesit pages 4-5).

2) Key molecular players - Genes/Proteins (HGNC symbols where relevant) • BBK32 (borrelial lipoprotein; complement C1r inhibitor and fibronectin adhesin) – classical complement pathway evasion; fibronectin binding (GO:0006956; GO:0005515) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). • CspA (CRASP family; factor H–binding) – alternative pathway inhibition (GO:0030449 complement regulation) (farooq2025osteoimmunologicalcharacterizationof pages 42-44). • CspZ (CRASP family; factor H–binding) – host-specific FH binding contributing to tropism (farooq2025osteoimmunologicalcharacterizationof pages 42-44). • OspE paralogs (CRASP family; FH/FHL-1 binding) – alternative pathway evasion (farooq2025osteoimmunologicalcharacterizationof pages 42-44). • VlsE – antigenic variation via gene conversion; immune evasion (GO:0019048 modulation by host) (farooq2025osteoimmunologicalcharacterizationof pages 42-44). • DbpA/DbpB – decorin binding; ECM adhesion and tissue localization (GO:0007155 cell adhesion) (nasrallah2023screeninginsilico pages 8-14). • OspC – early infection factor; vector-host immune-modulatory interactions (farooq2025osteoimmunologicalcharacterizationof pages 42-44).

Chemical entities (CHEBI) • Complement components targeted functionally (C1r, C4 deposition reduced by BBK32 activity) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). • Host GAGs and ECM ligands (fibronectin, decorin) engaged by BBK32/DbpA/DbpB (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14).
Cell types (CL) • Neutrophils and macrophages responding to spirochetal peptidoglycan and lipoproteins (elevated inflammatory cytokines/chemokines) (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). • Endothelial cells at vascular interface for adhesion/extravasation (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14). • T and B lymphocytes in post-infectious dysregulation/autoimmunity hypotheses (wester2024whatmakesit pages 4-5).
Anatomical locations (UBERON) • Skin at bite site; blood vasculature and endothelium during dissemination; joints (synovium) and nervous system in disseminated disease (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14, farooq2025osteoimmunologicalcharacterizationofa pages 35-38, wester2024whatmakesit pages 4-5).

3) Biological processes (candidate GO annotations) - Complement evasion and regulation: negative regulation of complement activation (GO:0045916); classical pathway inhibition via C1r interaction (BBK32) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). - Adhesion and dissemination: cell adhesion (GO:0007155), extracellular matrix binding (GO:0050840), plasminogen activation-dependent migration (GO:0031639) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14). - Antigenic variation: DNA recombination and gene conversion (GO:0006310) at vlsE (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - Chemotaxis and motility: chemotaxis (GO:0006935) and locomotion (GO:0040011) of spirochetes (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). - Cytokine-mediated signaling: inflammatory response (GO:0006954) with IL-6, IL-8, TNF, CCL3/4 upregulation (farooq2025osteoimmunologicalcharacterizationofa pages 35-38).

4) Cellular components (GO CC) - Outer membrane and surface-exposed lipoprotein layer where BBK32, OspC, DbpA/B, and CRASPs reside (GO:0009279 cell outer membrane) (farooq2025osteoimmunologicalcharacterizationof pages 42-44, powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14). - Extracellular matrix (host) for fibronectin/decorin binding (GO:0031012 extracellular matrix) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14). - Periplasmic space with peptidoglycan and periplasmic flagella (GO:0030288 outer membrane-bounded periplasmic space) (farooq2025osteoimmunologicalcharacterizationofa pages 35-38).

5) Disease progression (sequence of events) - Tick feeding induces OspC upregulation and transmission from midgut to salivary glands; early dermal colonization follows (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - Early localized infection: erythema migrans with high local innate activation to lipoproteins/peptidoglycan (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). - Hematogenous dissemination: BBK32–fibronectin and DbpA/B–decorin interactions promote vascular adhesion and tissue entry; classical complement inhibition (BBK32) and alternative pathway inhibition (CRASPs) permit survival in serum and tissues (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14, farooq2025osteoimmunologicalcharacterizationof pages 42-44). - Disseminated infection: involvement of joints, nervous system, heart; cytokine/chemokine programs vary by tissue, with IL-6 prominent in neuroinflammatory contexts (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - Post-infectious sequelae in subsets: persistent symptoms ≥6 months (PTLDS) with associations to immune dysregulation and elevated early CCL19; autoimmunity hypothesized in joint disease (wester2024whatmakesit pages 4-5).

6) Phenotypic manifestations and mechanistic links (HP terms) - Early localized skin lesion: erythema migrans (HP:0000978) linked to dermal innate responses to lipoproteins/peptidoglycan (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). - Neuroborreliosis: radiculitis, meningitis, cranial neuropathies (HP:0001288, HP:0003401) with cytokine-driven neuroinflammation (e.g., IL-6) (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - Lyme arthritis: episodic or persistent synovitis (HP:0100769) connected to strong inflammatory responses; in some patients, post-infectious immune dysregulation/autoimmunity (wester2024whatmakesit pages 4-5). - PTLDS: fatigue, pain, cognitive complaints persisting >6 months after therapy (HP:0012378, HP:0002355) with reported 10–20% incidence and evidence for immune activation signatures (wester2024whatmakesit pages 4-5).

Evidence items (primary literature; URLs and dates where available) - BBK32 and complement evasion/adhesion: Powell-Pierce AD et al. BBK32 attenuates antibody-dependent complement-mediated killing of infectious Borreliella burgdorferi isolates. PLOS Pathogens, 2025-07; doi:10.1371/journal.ppat.1013361; URL: https://doi.org/10.1371/journal.ppat.1013361 (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). - CRASPs, VlsE antigenic variation, OspC stage regulation, ECM interactions, and IL-6 in neuroinflammation: Farooq I. Osteoimmunological characterization of Borrelia burgdorferi-induced bone loss: From phenotype to molecular mechanisms. 2025 (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - Peptidoglycan location, periplasmic flagella, motility/chemotaxis, and stronger proinflammatory cytokine induction by B. burgdorferi vs. some Eurasian species: Farooq I. 2025 (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). - ECM adhesion repertoire, integrin/plasminogen pathways aiding invasion; DbpA/BBK32 as adhesins: Nasrallah H. Screening in silico… 2023 (nasrallah2023screeninginsilico pages 8-14). - PTLDS burden (10–20%), transcriptomic persistence after treatment, and early CCL19 as a risk indicator for later PTLDS: Wester KE et al. Cureus, 2024-07; doi:10.7759/cureus.64987; URL: https://doi.org/10.7759/cureus.64987 (wester2024whatmakesit pages 4-5).

Gene/protein annotations with ontology terms - BBK32 (borrelial lipoprotein; adhesin and complement inhibitor) • Functions: fibronectin binding (GO:0005515), negative regulation of classical complement activation (GO:0045916) • Process: cell adhesion (GO:0007155); immune evasion (GO:0006956) • Cellular component: outer membrane (GO:0009279) • Evidence: (powellpierce2025bbk32attenuatesantibodydependent pages 19-20) - CspA/CspZ/OspE family (CRASPs) • Functions: factor H/FHL-1 binding; negative regulation of alternative pathway (GO:0045916) • Component: outer membrane (GO:0009279) • Evidence: (farooq2025osteoimmunologicalcharacterizationof pages 42-44, powellpierce2025bbk32attenuatesantibodydependent pages 19-20) - VlsE • Process: antigenic variation via gene conversion/recombination (GO:0006310) • Component: outer membrane lipoprotein layer (GO:0009279) • Evidence: (farooq2025osteoimmunologicalcharacterizationof pages 42-44) - DbpA/DbpB • Functions: decorin binding; ECM binding (GO:0050840) • Process: cell adhesion (GO:0007155) • Evidence: (nasrallah2023screeninginsilico pages 8-14) - OspC • Process: early infection/host colonization; interaction with Salp15 (vector immune modulation) • Evidence: (farooq2025osteoimmunologicalcharacterizationof pages 42-44)

Cell type involvement (CL terms) - Endothelial cell (CL:0000115): vascular adhesion/extravasation interface (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14) - Neutrophil (CL:0000096) and macrophage (CL:0000235): early innate cytokine responses to peptidoglycan/lipoproteins (farooq2025osteoimmunologicalcharacterizationofa pages 35-38) - T cell (CL:0000084) and B cell (CL:0000236): adaptive responses; dysregulation in PTLDS hypotheses (wester2024whatmakesit pages 4-5)

Anatomical locations (UBERON terms) - Skin (UBERON:0002097): inoculation site and early colonization (farooq2025osteoimmunologicalcharacterizationof pages 42-44) - Blood vessel/endothelium (UBERON:0001981/0001986): dissemination axis (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14) - Synovial membrane (UBERON:0002387): Lyme arthritis site (wester2024whatmakesit pages 4-5) - Central nervous system/meninges (UBERON:0001017/0002410): neuroinflammatory involvement (farooq2025osteoimmunologicalcharacterizationof pages 42-44)

Chemical entities (CHEBI) - Complement components (e.g., C1r, C4) (CHEBI:4887 C1r; CHEBI:33697 C4) as functional targets of BBK32-mediated inhibition (powellpierce2025bbk32attenuatesantibodydependent pages 19-20) - Fibronectin (CHEBI:8009; proteinaceous ECM) and decorin (CHEBI:16991; proteoglycan core protein) as host ligands for adhesion (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, nasrallah2023screeninginsilico pages 8-14) - Glycosaminoglycans (CHEBI:18085) in ECM binding (powellpierce2025bbk32attenuatesantibodydependent pages 19-20)

Expert opinions and analysis (authoritative perspectives) - Complement evasion is multifactorial and redundant. The BBK32 study demonstrates simultaneous binding to fibronectin and C1r, underscoring that adhesion and immune evasion are coupled rather than sequential, a principle that helps explain efficient dissemination despite antibody/complement pressure (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). - Antigenic variation at vlsE is a sustained, cassette-driven engine for immune escape in mammalian hosts, complementing complement evasion proteins and explaining serologic complexity and persistence under immune pressure (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - PTLDS remains mechanistically heterogeneous; however, data synthesized in recent clinical reviews point to persistent immune activation, early chemokine risk signals (CCL19), and a subset of autoimmune phenomena, aligning with a model of post-infectious immune dysregulation rather than ongoing high-burden viable infection in most cases (wester2024whatmakesit pages 4-5).

Relevant statistics and data - PTLDS prevalence: approximately 10–20% of treated Lyme disease patients; early elevated CCL19 (~>112 pg/mL at 1 month) associated with markedly higher risk of PTLDS at 6–12 months (wester2024whatmakesit pages 4-5). - Motility: B. burgdorferi achieves speeds up to ~4.25 μm/s; chemotaxis toward N-acetylglucosamine, glucosamine, chitosan, glutamate reported, consistent with nutrient-sensing dissemination (farooq2025osteoimmunologicalcharacterizationofa pages 35-38). - Antigenic variation architecture: vlsE with ~15 silent cassettes contributing to continual sequence diversification (farooq2025osteoimmunologicalcharacterizationof pages 42-44).

Limitations and gaps (2023–2024 focus) - While 2024–2025 primary data robustly support BBK32-mediated classical pathway inhibition and dual-function adhesion, larger in vivo human correlative datasets linking specific adhesin/CRASP expression patterns to clinical phenotypes remain limited (powellpierce2025bbk32attenuatesantibodydependent pages 19-20, farooq2025osteoimmunologicalcharacterizationof pages 42-44). - High-quality prospective biomarker studies for neuroborreliosis (e.g., CSF chemokines) and PTLDS are still sparse; CCL19 is a candidate but needs external validation and standardization (wester2024whatmakesit pages 4-5).

References (with citation IDs) - Powell-Pierce AD, et al. BBK32 attenuates antibody-dependent complement-mediated killing… PLOS Pathogens. 2025-07. https://doi.org/10.1371/journal.ppat.1013361 (powellpierce2025bbk32attenuatesantibodydependent pages 19-20) - Farooq I. Osteoimmunological characterization of Borrelia burgdorferi-induced bone loss… 2025. [Mechanistic review content on CRASPs, vlsE, OspC, IL-6] (farooq2025osteoimmunologicalcharacterizationof pages 42-44) - Farooq I. Osteoimmunological characterization… (peptidoglycan, motility/chemotaxis, cytokines). 2025. (farooq2025osteoimmunologicalcharacterizationofa pages 35-38) - Nasrallah H. Screening in silico… OspA/vector proteins; DbpA, BBK32, plasminogen/integrins. 2023. (nasrallah2023screeninginsilico pages 8-14) - Wester KE, et al. What Makes It Tick: Exploring the Mechanisms of Post-treatment Lyme Disease Syndrome. Cureus. 2024-07. https://doi.org/10.7759/cureus.64987 (wester2024whatmakesit pages 4-5)

Notes on evidence strength - BBK32 mechanistic inhibition of the classical pathway and concurrent fibronectin binding has strong experimental support (binding/functional assays) (powellpierce2025bbk32attenuatesantibodydependent pages 19-20). - CRASP-mediated alternative pathway evasion and vlsE-driven antigenic variation are supported by convergent lines of evidence across models (farooq2025osteoimmunologicalcharacterizationof pages 42-44). - PTLDS immunopathophysiology remains an active research area; clinical synthesis suggests immune dysregulation and biomarkers such as CCL19 may stratify risk, but causal chains are not fully established (wester2024whatmakesit pages 4-5).

References

(powellpierce2025bbk32attenuatesantibodydependent pages 19-20): Alexandra D. Powell-Pierce, Charles E. Booth, Payton G. Smith, Brittany L. Shapiro, Shannon S. Allen, Brandon L. Garcia, and Jon T. Skare. Bbk32 attenuates antibody-dependent complement-mediated killing of infectious borreliella burgdorferi isolates. PLOS Pathogens, 21:e1013361, Jul 2025. URL: https://doi.org/10.1371/journal.ppat.1013361, doi:10.1371/journal.ppat.1013361. This article has 0 citations and is from a highest quality peer-reviewed journal.
(farooq2025osteoimmunologicalcharacterizationof pages 42-44): I Farooq. Osteoimmunological characterization of borrelia burgdorferi-induced bone loss: from phenotype to molecular mechanisms. Unknown journal, 2025.
(nasrallah2023screeninginsilico pages 8-14): H NASRALLAH. Screening in silico delle interazioni proteina-proteina tra borrelia burgdorferi e zecche: uno studio di fattibilità su ospa e proteine salivari di zecca. Unknown journal, 2023.
(farooq2025osteoimmunologicalcharacterizationofa pages 35-38): I Farooq. Osteoimmunological characterization of borrelia burgdorferi-induced bone loss: from phenotype to molecular mechanisms. Unknown journal, 2025.
(wester2024whatmakesit pages 4-5): Kate E Wester, Bianca C Nwokeabia, Rehana Hassan, Taylor Dunphy, Michael Osondu, Carson Wonders, and Misbahuddin Khaja. What makes it tick: exploring the mechanisms of post-treatment lyme disease syndrome. Cureus, Jul 2024. URL: https://doi.org/10.7759/cureus.64987, doi:10.7759/cureus.64987. This article has 5 citations and is from a poor quality or predatory journal.

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