Lymphogranuloma Venereum

Infectious Disease MONDO:0005834 Pathograph 15 Show in embeddings browser Bacterial Infection Sexually transmitted infection

Lymphogranuloma venereum is a sexually transmitted invasive chlamydial infection caused by Chlamydia trachomatis serovars L1, L2, and L3. The organism enters mucosal epithelial cells, can replicate in macrophages, and causes genital ulceration, regional lymphadenopathy, and anorectal proctitis. Untreated disease can progress to a tertiary stage of lymphatic obstruction and fibrosis, with genital elephantiasis and anorectal strictures and fistulae. Doxycycline is the standard prolonged oral antibiotic therapy.

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6
Pathophys.
8
Phenotypes
15
Pathograph
1
Medical Actions
1
Deep Research
🏷

Classifications

Harrison's Part
INFECTIOUS DISEASES
⚙

Pathophysiology

6
C. trachomatis T3SS-Dependent Epithelial Entry
C. trachomatis elementary bodies attach to mucosal epithelial cells and use type III secretion system effectors to enter host cells, manipulate the inclusion membrane, and complete the intracellular developmental cycle.
epithelial cell CL:0000066 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves epithelial cell (CL:0000066). CL:0000066 is a cell type from the Cell Ontology.
symbiont entry into host cell GO:0046718 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased symbiont entry into host cell (GO:0046718). GO:0046718 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (1 reference)
PMID:33512479 SUPPORT Other
"C. trachomatis delivers an arsenal of virulence factors into the eukaryotic cell via a type 3 secretion system (T3SS) that facilitates invasion, manipulation of host vesicular trafficking, subversion of host defense mechanisms and promotes bacteria egress at the conclusion of the developmental cycle."
Review tying the T3SS to C. trachomatis invasion, inclusion manipulation, immune subversion, and egress.
L2 Macrophage Replication and Cytokine Skewing
Disseminating C. trachomatis serovar L2 can replicate in monocyte-derived macrophages and induces a cytokine profile distinct from the non-disseminating E serovar, linking intracellular survival to neutrophil and macrophage recruitment.
macrophage CL:0000235 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves macrophage (CL:0000235). CL:0000235 is a cell type from the Cell Ontology. neutrophil CL:0000775 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neutrophil (CL:0000775). CL:0000775 is a cell type from the Cell Ontology.
inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (2 references)
PMID:3759241 SUPPORT In Vitro
"In contrast to the abortive replication of C. trachomatis in monocytes, monocyte-derived macrophages permitted replication as indicated by one-step growth experiments and TEM."
Directly demonstrates productive L2 replication in human monocyte-derived macrophages.
PMID:11207588 SUPPORT In Vitro
"Infection of HeLa cells with C. trachomatis E or L2 induced a strong and similar PMN chemotactic response, but larger amounts of interleukin (IL)-8 and IL-11 were released after infection with serovar L2."
Shows that a disseminating L2 strain elicits a distinct epithelial cytokine profile while preserving neutrophil chemotactic signaling.
Regional Lymphadenitis
After a primary inoculation-site papule or ulcer, invasive L-serovar infection produces regional, usually unilateral inguinal lymphadenopathy - the classic second-stage inguinal syndrome.
inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"The clinical course can be classically divided into three stages: an initial papule, which may ulcerate at the site of inoculation, followed by regional lymphoadenopathy (second stage, generally unilateral)."
Describes the transition from an inoculation-site lesion to secondary regional lymphadenopathy.
Ulcerative Proctitis
In the contemporary MSM-associated anorectal epidemic, invasive L-serovar infection produces progressive ulcerative proctitis - the dominant modern LGV syndrome.
inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"The main clinical picture is a relative new entity characterized by progressive ulcerative proctitis, the so called anorectal syndrome."
Establishes ulcerative proctitis as the dominant contemporary LGV syndrome.
Lymphatic Fibrosis and Obstruction
Untreated LGV can progress to a tertiary stage in which chronic inflammation produces lymphatic obstruction and fibrotic scarring, causing genital elephantiasis and anorectal strictures and fistulae. The IFN-gamma / Th1 and matrix-metalloproteinase remodeling behind the scarring is extrapolated from ocular C. trachomatis (trachoma), where it is established.
inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (2 references)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"In the tertiary stage, lymphatic obstruction, with elephantiasis of genitalia, and rectal involvement can lead to the formation of strictures and fistulae that may require surgical treatment."
Establishes the tertiary stage of lymphatic obstruction, elephantiasis, strictures, and fistulae.
PMID:23457650 SUPPORT INDIRECT REVIEW SYNTHESIS Human Clinical
"changes in matrix metalloproteinase activity, are important in the development of tissue damage and scarring."
Matrix-metalloproteinase-driven scarring in ocular C. trachomatis, cited as the extrapolated mechanism for LGV tertiary fibrosis (INDIRECT).
Chlamydial Ribosomal Translation (Tetracycline Target)
C. trachomatis requires its bacterial 70S ribosome for protein synthesis. Doxycycline blocks translation through the 30S subunit, giving LGV a tetracycline-vulnerable replication step.
translation GO:0006412 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves translation (GO:0006412). GO:0006412 is a biological process from the Gene Ontology.
Show evidence (1 reference)
PMID:24336183 SUPPORT Other
"The ribosome is one of the main antibiotic targets in the bacterial cell."
Review establishing the bacterial ribosome as the shared target of tetracyclines and other protein-synthesis inhibitors.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Lymphogranuloma Venereum Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

8
Blood 1
Hematochezia HP:0002573 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hematochezia (HP:0002573). HP:0002573 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34057249 SUPPORT Other
"The symptoms of proctitis include anorectal itching, pain, tenesmus, bleeding, constipation and discharge in and around the anal canal."
Lists bleeding among the symptoms of sexually transmissible proctitis.
Cardiovascular 1
Lymphadenopathy HP:0002716 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Lymphadenopathy (HP:0002716). HP:0002716 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"The clinical course can be classically divided into three stages: an initial papule, which may ulcerate at the site of inoculation, followed by regional lymphoadenopathy (second stage, generally unilateral)."
Describes unilateral regional lymphadenopathy as the second LGV stage.
Digestive 4
Tenesmus HP:0012702 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Tenesmus (HP:0012702). HP:0012702 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34057249 SUPPORT Other
"The symptoms of proctitis include anorectal itching, pain, tenesmus, bleeding, constipation and discharge in and around the anal canal."
Lists tenesmus among the symptoms of sexually transmissible proctitis.
Constipation HP:0002019 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Constipation (HP:0002019). HP:0002019 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34057249 SUPPORT Other
"The symptoms of proctitis include anorectal itching, pain, tenesmus, bleeding, constipation and discharge in and around the anal canal."
Lists constipation among the symptoms of sexually transmissible proctitis.
Anorectal stricture Anal stenosis HP:0002025 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Anorectal stricture, annotated with Anal stenosis (HP:0002025). HP:0002025 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"rectal involvement can lead to the formation of strictures and fistulae that may require surgical treatment."
Rectal involvement produces tertiary anorectal strictures.
Anal fistula HP:0010447 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Anal fistula (HP:0010447). HP:0010447 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"rectal involvement can lead to the formation of strictures and fistulae that may require surgical treatment."
Rectal involvement produces tertiary anorectal fistulae.
Genitourinary 1
Genital ulcers HP:0003249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Genital ulcers (HP:0003249). HP:0003249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"The clinical course can be classically divided into three stages: an initial papule, which may ulcerate at the site of inoculation, followed by regional lymphoadenopathy (second stage, generally unilateral)."
Describes genital or anorectal inoculation-site papules as the primary lesions that may ulcerate in LGV.
Metabolism 1
Lymphedema HP:0001004 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Genital elephantiasis (lymphedema), annotated with Lymphedema (HP:0001004). HP:0001004 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24518282 SUPPORT REVIEW SYNTHESIS Human Clinical
"In the tertiary stage, lymphatic obstruction, with elephantiasis of genitalia, and rectal involvement can lead to the formation of strictures and fistulae that may require surgical treatment."
Genital elephantiasis from lymphatic obstruction is the tertiary lymphedema phenotype.
💊

Medical Actions

1
Doxycycline
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: doxycycline CHEBI:50845 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses doxycycline (CHEBI:50845). CHEBI:50845 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Doxycycline 100 mg twice daily for 21 days is the recommended LGV regimen; it inhibits chlamydial growth by targeting the bacterial ribosome.
Mechanism Target:
INHIBITS Chlamydial Ribosomal Translation (Tetracycline Target) — Doxycycline binds the bacterial 30S ribosome and arrests C. trachomatis protein synthesis.
Show evidence (2 references)
PMID:31243838 SUPPORT Other
"Doxycycline 100 mg twice a day orally for 21 days is the recommended treatment for LGV."
Guideline statement of the recommended doxycycline regimen for LGV.
PMID:27513890 SUPPORT Human Clinical
"The fixed-effects pooled efficacy for doxycycline was 98.5% (95% CI 96.3%-100%, I (2) = 0%; p = 0.993)."
Meta-analysis of rectal LGV treatment in MSM measuring a high microbial cure rate for the same 21-day doxycycline regimen.
🔬

Diagnosis

1
NAAT with LGV-discriminatory genotyping
LGV diagnosis is a two-step algorithm: a C. trachomatis nucleic acid amplification test on the specimen, followed by LGV-discriminatory pmpH and ompA genotyping to confirm an L serovar.
nucleic acid amplification test with pmpH/ompA genotyping NCIT:C20055 NCI Thesaurus (NCIT)
Show evidence (3 references)
PMID:22517888 SUPPORT Human Clinical
"Altogether 140 C trachomatis NAAT-positive rectal and pharyngeal samples were genotyped by pmpH and ompA real-time PCR."
NAAT-positive specimens are genotyped by pmpH and ompA PCR to identify LGV.
PMID:31243838 SUPPORT REVIEW SYNTHESIS Human Clinical
"a commercial nucleic acid amplification test (NAAT) platform should be confirmed with an LGV discriminatory NAAT."
The guideline states the two-step algorithm, in which a C. trachomatis NAAT is confirmed by an LGV-discriminatory NAAT.
PMID:16721218 SUPPORT PRIMARY RESULT Human Clinical
"It is important for gastroenterologists to recognize that LGV may be reemerging as a relevant clinical entity, because of its similarity to inflammatory bowel diseases"
A case series' authors conclude LGV proctitis mimics inflammatory bowel disease, which explains diagnostic delay.
📊

Prevalence

1
Spain, 2018-2019 (predominantly MSM)
Cases In Literature Not yet documented
Contemporary LGV is concentrated in men who have sex with men; a Spanish molecular-epidemiology series characterized 161 isolates.
Show evidence (1 reference)
PMID:39053939 SUPPORT Human Clinical
"Most of the 161 LGV isolates (93.8%) were detected in men who have sex with men (MSM)."
A Spanish series of 161 LGV isolates found 93.8% in men who have sex with men.
🦠

Infectious Agent

1
Chlamydia trachomatis L1-L3 serovars
Invasive C. trachomatis serovars L1, L2, and L3 cause lymphogranuloma venereum; recent outbreaks are mostly due to the L2b type.
Chlamydia trachomatis NCBITaxon:813 NCBI Taxonomy (NCBITaxon)
Show evidence (1 reference)
PMID:24518282 SUPPORT Other
"The etiological agent of LGV is Chlamydia trachomatis serotypes L1, L2 and L3, and current outbreaks are mostly sustained by L2b type."
Review identifying C. trachomatis L1-L3 as the causative organisms, with L2b predominance in contemporary outbreaks.
↔️

Transmission

1
Sexual transmission
Chlamydia trachomatis L serovars are transmitted by sexual contact at genital, rectal, or oropharyngeal mucosal sites; anorectal transmission through genital-anal contact is prominent in the contemporary MSM-associated epidemic.
Show evidence (1 reference)
PMID:34057249 SUPPORT Other
"Infectious proctitis can be sexually transmitted via genital-anal mucosal contact, but some also via digital contact and toys."
Guideline statement establishing sexual mucosal contact as a route for infectious proctitis, the syndrome that includes LGV proctitis.
{ }

Source YAML

click to show
name: Lymphogranuloma Venereum
creation_date: '2026-09-25T00:00:00Z'
category: Infectious Disease
description: >-
  Lymphogranuloma venereum is a sexually transmitted invasive chlamydial
  infection caused by Chlamydia trachomatis serovars L1, L2, and L3. The
  organism enters mucosal epithelial cells, can replicate in macrophages, and
  causes genital ulceration, regional lymphadenopathy, and anorectal proctitis.
  Untreated disease can progress to a tertiary stage of lymphatic obstruction
  and fibrosis, with genital elephantiasis and anorectal strictures and
  fistulae. Doxycycline is the standard prolonged oral antibiotic therapy.
disease_term:
  preferred_term: lymphogranuloma venereum
  term:
    id: MONDO:0005834
    label: lymphogranuloma venereum
parents:
- Bacterial Infection
- Sexually transmitted infection
synonyms:
- LGV
- Lymphogranuloma inguinale
- Durand-Nicolas-Favre disease
- Climatic bubo
- Tropical bubo
- Poradenitis
- Lymphopathia venereum
classifications:
  harrisons_chapter:
  - classification_value: INFECTIOUS_DISEASES
infectious_agent:
- name: Chlamydia trachomatis L1-L3 serovars
  description: >-
    Invasive C. trachomatis serovars L1, L2, and L3 cause lymphogranuloma
    venereum; recent outbreaks are mostly due to the L2b type.
  infectious_agent_term:
    preferred_term: Chlamydia trachomatis
    term:
      id: NCBITaxon:813
      label: Chlamydia trachomatis
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The etiological agent of LGV is Chlamydia trachomatis serotypes L1, L2 and
      L3, and current outbreaks are mostly sustained by L2b type.
    explanation: >-
      Review identifying C. trachomatis L1-L3 as the causative organisms, with
      L2b predominance in contemporary outbreaks.
transmission:
- name: Sexual transmission
  description: >-
    Chlamydia trachomatis L serovars are transmitted by sexual contact at
    genital, rectal, or oropharyngeal mucosal sites; anorectal transmission
    through genital-anal contact is prominent in the contemporary MSM-associated
    epidemic.
  evidence:
  - reference: PMID:34057249
    reference_title: "2021 European Guideline on the management of proctitis, proctocolitis and enteritis caused by sexually transmissible pathogens."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Infectious proctitis can be sexually transmitted via genital-anal mucosal
      contact, but some also via digital contact and toys.
    explanation: >-
      Guideline statement establishing sexual mucosal contact as a route for
      infectious proctitis, the syndrome that includes LGV proctitis.
pathophysiology:
- name: C. trachomatis T3SS-Dependent Epithelial Entry
  description: >-
    C. trachomatis elementary bodies attach to mucosal epithelial cells and use
    type III secretion system effectors to enter host cells, manipulate the
    inclusion membrane, and complete the intracellular developmental cycle.
  role: trigger
  cell_types:
  - preferred_term: epithelial cell
    term:
      id: CL:0000066
      label: epithelial cell
  biological_processes:
  - preferred_term: symbiont entry into host cell
    modifier: INCREASED
    term:
      id: GO:0046718
      label: symbiont entry into host cell
  evidence:
  - reference: PMID:33512479
    reference_title: "Got mutants? How advances in chlamydial genetics have furthered the study of effector proteins."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      C. trachomatis delivers an arsenal of virulence factors into the eukaryotic
      cell via a type 3 secretion system (T3SS) that facilitates invasion,
      manipulation of host vesicular trafficking, subversion of host defense
      mechanisms and promotes bacteria egress at the conclusion of the
      developmental cycle.
    explanation: >-
      Review tying the T3SS to C. trachomatis invasion, inclusion manipulation,
      immune subversion, and egress.
  downstream:
  - target: L2 Macrophage Replication and Cytokine Skewing
    description: >-
      Intracellular epithelial infection is followed by productive L2 replication
      in macrophages and an L2-skewed cytokine profile.
  - target: Genital ulcers
    description: >-
      Initial inoculation-site lesions can ulcerate before the secondary stage of
      lymphadenopathy or proctitis.
- name: L2 Macrophage Replication and Cytokine Skewing
  description: >-
    Disseminating C. trachomatis serovar L2 can replicate in monocyte-derived
    macrophages and induces a cytokine profile distinct from the
    non-disseminating E serovar, linking intracellular survival to neutrophil and
    macrophage recruitment.
  role: mechanism
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  evidence:
  - reference: PMID:3759241
    reference_title: Fate of Chlamydia trachomatis in human monocytes and monocyte-derived macrophages.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In contrast to the abortive replication of C. trachomatis in monocytes,
      monocyte-derived macrophages permitted replication as indicated by one-step
      growth experiments and TEM.
    explanation: >-
      Directly demonstrates productive L2 replication in human
      monocyte-derived macrophages.
  - reference: PMID:11207588
    reference_title: Chlamydial infection of polarized HeLa cells induces PMN chemotaxis but the cytokine profile varies between disseminating and non-disseminating strains.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Infection of HeLa cells with C. trachomatis E or L2 induced a strong and
      similar PMN chemotactic response, but larger amounts of interleukin (IL)-8
      and IL-11 were released after infection with serovar L2.
    explanation: >-
      Shows that a disseminating L2 strain elicits a distinct epithelial
      cytokine profile while preserving neutrophil chemotactic signaling.
  downstream:
  - target: Regional Lymphadenitis
    description: >-
      L2 replication in phagocytes and cytokine-biased inflammation precede the
      classic inguinal lymphadenitis syndrome of LGV.
  - target: Ulcerative Proctitis
    description: >-
      In the contemporary anorectal epidemic, invasive L-serovar infection
      produces progressive ulcerative proctitis.
- name: Regional Lymphadenitis
  description: >-
    After a primary inoculation-site papule or ulcer, invasive L-serovar
    infection produces regional, usually unilateral inguinal lymphadenopathy -
    the classic second-stage inguinal syndrome.
  role: consequence
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The clinical course can be classically divided into three stages: an
      initial papule, which may ulcerate at the site of inoculation, followed by
      regional lymphoadenopathy (second stage, generally unilateral).
    explanation: >-
      Describes the transition from an inoculation-site lesion to secondary
      regional lymphadenopathy.
  downstream:
  - target: Lymphadenopathy
    description: Regional lymph node inflammation produces the secondary-stage lymphadenopathy.
  - target: Lymphatic Fibrosis and Obstruction
    description: >-
      Untreated regional lymphatic infection can progress to chronic
      scarring and lymphatic obstruction.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
- name: Ulcerative Proctitis
  description: >-
    In the contemporary MSM-associated anorectal epidemic, invasive L-serovar
    infection produces progressive ulcerative proctitis - the dominant modern
    LGV syndrome.
  role: consequence
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The main clinical picture is a relative new entity characterized by
      progressive ulcerative proctitis, the so called anorectal syndrome.
    explanation: >-
      Establishes ulcerative proctitis as the dominant contemporary LGV syndrome.
  downstream:
  - target: Tenesmus
    description: Ulcerative proctitis can cause tenesmus.
  - target: Hematochezia
    description: Ulcerative proctitis can cause anorectal bleeding.
  - target: Constipation
    description: Ulcerative proctitis can cause constipation.
  - target: Lymphatic Fibrosis and Obstruction
    description: >-
      Chronic anorectal LGV can progress to fibrotic strictures and fistulae.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
- name: Lymphatic Fibrosis and Obstruction
  description: >-
    Untreated LGV can progress to a tertiary stage in which chronic
    inflammation produces lymphatic obstruction and fibrotic scarring, causing
    genital elephantiasis and anorectal strictures and fistulae. The IFN-gamma /
    Th1 and matrix-metalloproteinase remodeling behind the scarring is
    extrapolated from ocular C. trachomatis (trachoma), where it is established.
  role: consequence
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      In the tertiary stage, lymphatic obstruction, with elephantiasis of
      genitalia, and rectal involvement can lead to the formation of strictures
      and fistulae that may require surgical treatment.
    explanation: Establishes the tertiary stage of lymphatic obstruction, elephantiasis, strictures, and fistulae.
  - reference: PMID:23457650
    reference_title: "Trachoma: protective and pathogenic ocular immune responses to Chlamydia trachomatis."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      changes in matrix metalloproteinase activity, are important in the
      development of tissue damage and scarring.
    explanation: >-
      Matrix-metalloproteinase-driven scarring in ocular C. trachomatis, cited
      as the extrapolated mechanism for LGV tertiary fibrosis (INDIRECT).
  downstream:
  - target: Lymphedema
    description: Lymphatic obstruction produces genital elephantiasis.
  - target: Anorectal stricture
    description: Chronic fibrosis produces anorectal strictures.
  - target: Anal fistula
    description: Chronic fibrosis produces anorectal fistulae.
- name: Chlamydial Ribosomal Translation (Tetracycline Target)
  role: therapeutic_vulnerability
  conforms_to: "bacterial_protein_synthesis_inhibition#Bacterial mRNA Translation by the Ribosome"
  description: >-
    C. trachomatis requires its bacterial 70S ribosome for protein synthesis.
    Doxycycline blocks translation through the 30S subunit, giving LGV a
    tetracycline-vulnerable replication step.
  biological_processes:
  - preferred_term: translation
    term:
      id: GO:0006412
      label: translation
  evidence:
  - reference: PMID:24336183
    reference_title: Ribosome-targeting antibiotics and mechanisms of bacterial resistance.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The ribosome is one of the main antibiotic targets in the bacterial cell.
    explanation: >-
      Review establishing the bacterial ribosome as the shared target of
      tetracyclines and other protein-synthesis inhibitors.
phenotypes:
- name: Genital ulcers
  description: LGV primary papules at the site of inoculation may ulcerate.
  phenotype_term:
    preferred_term: Genital ulcers
    term:
      id: HP:0003249
      label: Genital ulcers
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The clinical course can be classically divided into three stages: an
      initial papule, which may ulcerate at the site of inoculation, followed by
      regional lymphoadenopathy (second stage, generally unilateral).
    explanation: >-
      Describes genital or anorectal inoculation-site papules as the primary
      lesions that may ulcerate in LGV.
- name: Lymphadenopathy
  description: Regional, usually unilateral lymphadenopathy is the classic secondary stage of LGV.
  phenotype_term:
    preferred_term: Lymphadenopathy
    term:
      id: HP:0002716
      label: Lymphadenopathy
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The clinical course can be classically divided into three stages: an
      initial papule, which may ulcerate at the site of inoculation, followed by
      regional lymphoadenopathy (second stage, generally unilateral).
    explanation: Describes unilateral regional lymphadenopathy as the second LGV stage.
- name: Tenesmus
  description: LGV proctitis can cause tenesmus.
  phenotype_term:
    preferred_term: Tenesmus
    term:
      id: HP:0012702
      label: Tenesmus
  evidence:
  - reference: PMID:34057249
    reference_title: "2021 European Guideline on the management of proctitis, proctocolitis and enteritis caused by sexually transmissible pathogens."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The symptoms of proctitis include anorectal itching, pain, tenesmus,
      bleeding, constipation and discharge in and around the anal canal.
    explanation: Lists tenesmus among the symptoms of sexually transmissible proctitis.
- name: Hematochezia
  description: LGV proctitis can cause anorectal bleeding.
  phenotype_term:
    preferred_term: Hematochezia
    term:
      id: HP:0002573
      label: Hematochezia
  evidence:
  - reference: PMID:34057249
    reference_title: "2021 European Guideline on the management of proctitis, proctocolitis and enteritis caused by sexually transmissible pathogens."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The symptoms of proctitis include anorectal itching, pain, tenesmus,
      bleeding, constipation and discharge in and around the anal canal.
    explanation: Lists bleeding among the symptoms of sexually transmissible proctitis.
- name: Constipation
  description: LGV proctitis can cause constipation.
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: PMID:34057249
    reference_title: "2021 European Guideline on the management of proctitis, proctocolitis and enteritis caused by sexually transmissible pathogens."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The symptoms of proctitis include anorectal itching, pain, tenesmus,
      bleeding, constipation and discharge in and around the anal canal.
    explanation: Lists constipation among the symptoms of sexually transmissible proctitis.
- name: Lymphedema
  description: >-
    Tertiary-stage lymphatic obstruction produces genital elephantiasis
    (lymphedema).
  phenotype_term:
    preferred_term: Genital elephantiasis (lymphedema)
    term:
      id: HP:0001004
      label: Lymphedema
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      In the tertiary stage, lymphatic obstruction, with elephantiasis of
      genitalia, and rectal involvement can lead to the formation of strictures
      and fistulae that may require surgical treatment.
    explanation: Genital elephantiasis from lymphatic obstruction is the tertiary lymphedema phenotype.
- name: Anorectal stricture
  description: >-
    Tertiary-stage anorectal LGV can produce fibrotic strictures that may
    require surgery.
  phenotype_term:
    preferred_term: Anorectal stricture
    term:
      id: HP:0002025
      label: Anal stenosis
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      rectal involvement can lead to the formation of strictures and fistulae
      that may require surgical treatment.
    explanation: Rectal involvement produces tertiary anorectal strictures.
- name: Anal fistula
  description: >-
    Tertiary-stage anorectal LGV can produce fistulae.
  phenotype_term:
    preferred_term: Anal fistula
    term:
      id: HP:0010447
      label: Anal fistula
  evidence:
  - reference: PMID:24518282
    reference_title: "Lymphogranuloma venereum: an old, forgotten re-emerging systemic disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      rectal involvement can lead to the formation of strictures and fistulae
      that may require surgical treatment.
    explanation: Rectal involvement produces tertiary anorectal fistulae.
diagnosis:
- name: NAAT with LGV-discriminatory genotyping
  description: >-
    LGV diagnosis is a two-step algorithm: a C. trachomatis nucleic acid
    amplification test on the specimen, followed by LGV-discriminatory pmpH and
    ompA genotyping to confirm an L serovar.
  diagnosis_term:
    preferred_term: nucleic acid amplification test with pmpH/ompA genotyping
    term:
      id: NCIT:C20055
      label: Nucleic Acid Amplification Test
  evidence:
  - reference: PMID:22517888
    reference_title: "Genotyping of Chlamydia trachomatis in rectal and pharyngeal specimens: identification of LGV genotypes in Finland."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Altogether 140 C trachomatis NAAT-positive rectal and pharyngeal samples
      were genotyped by pmpH and ompA real-time PCR.
    explanation: NAAT-positive specimens are genotyped by pmpH and ompA PCR to identify LGV.
  - reference: PMID:31243838
    reference_title: 2019 European guideline on the management of lymphogranuloma venereum.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      a commercial nucleic acid amplification test (NAAT) platform should be
      confirmed with an LGV discriminatory NAAT.
    explanation: >-
      The guideline states the two-step algorithm, in which a C. trachomatis
      NAAT is confirmed by an LGV-discriminatory NAAT.
  - reference: PMID:16721218
    reference_title: "Lymphogranuloma venereum in human immunodeficiency virus-infected individuals in New York City."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      It is important for gastroenterologists to recognize that LGV may be
      reemerging as a relevant clinical entity, because of its similarity to
      inflammatory bowel diseases
    explanation: A case series' authors conclude LGV proctitis mimics inflammatory bowel disease, which explains diagnostic delay.
prevalence:
- population: Spain, 2018-2019 (predominantly MSM)
  measure_type: CASES_IN_LITERATURE
  prevalence_class: NOT_YET_DOCUMENTED
  notes: >-
    Contemporary LGV is concentrated in men who have sex with men; a Spanish
    molecular-epidemiology series characterized 161 isolates.
  evidence:
  - reference: PMID:39053939
    reference_title: "Genetic characterisation of lymphogranuloma venereum in Spain: a multicentre study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Most of the 161 LGV isolates (93.8%) were detected in men who have sex with
      men (MSM).
    explanation: A Spanish series of 161 LGV isolates found 93.8% in men who have sex with men.
treatments:
- name: Doxycycline
  description: >-
    Doxycycline 100 mg twice daily for 21 days is the recommended LGV regimen;
    it inhibits chlamydial growth by targeting the bacterial ribosome.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: doxycycline
      term:
        id: CHEBI:50845
        label: doxycycline
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: Chlamydial Ribosomal Translation (Tetracycline Target)
    treatment_effect: INHIBITS
    description: >-
      Doxycycline binds the bacterial 30S ribosome and arrests C. trachomatis
      protein synthesis.
  evidence:
  - reference: PMID:31243838
    reference_title: 2019 European guideline on the management of lymphogranuloma venereum.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Doxycycline 100 mg twice a day orally for 21 days is the recommended
      treatment for LGV.
    explanation: Guideline statement of the recommended doxycycline regimen for LGV.
  - reference: PMID:27513890
    reference_title: Systematic Review and Meta-Analysis of Doxycycline Efficacy for Rectal Lymphogranuloma Venereum in Men Who Have Sex with Men.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The fixed-effects pooled efficacy for doxycycline was 98.5% (95% CI
      96.3%-100%, I (2)  = 0%; p = 0.993).
    explanation: >-
      Meta-analysis of rectal LGV treatment in MSM measuring a high microbial
      cure rate for the same 21-day doxycycline regimen.
notes: >-
  Curated from the OpenScientist report
  `research/Lymphogranuloma_Venereum-deep-research-openscientist.md`. The
  report-suggested HPO IDs `HP:0200037` and `HP:0002607` were rejected after term
  validation showed they label Skin vesicle and Bowel incontinence, respectively;
  the obsolete `GO:0009405` and `GO:0030260` suggestions were also not used.
📚

References & Deep Research

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (1)

Record notes

Curated from the OpenScientist report `research/Lymphogranuloma_Venereum-deep-research-openscientist.md`. The report-suggested HPO IDs `HP:0200037` and `HP:0002607` were rejected after term validation showed they label Skin vesicle and Bowel incontinence, respectively; the obsolete `GO:0009405` and `GO:0030260` suggestions were also not used.

OpenScientist ▸
Lymphogranuloma Venereum (MONDO:0005834): A Comprehensive Disease Characteristics Report
openscientist-autonomous 23 citations 2026-09-24T23:18:48.812693

Lymphogranuloma Venereum (MONDO:0005834): A Comprehensive Disease Characteristics Report

Target disease: Lymphogranuloma Venereum · MONDO:0005834 · Category: Infectious Disease Report type: Disease-level synthesis from primary literature and clinical guidelines (no patient-level data files were provided; all evidence is aggregated/literature-derived). Date: 2026-09-25

Summary

Lymphogranuloma venereum (LGV) is an invasive, systemic sexually transmitted infection caused by the L-biovar of Chlamydia trachomatis (serovars L1, L2, L2b, and L3). Unlike the non-invasive "trachoma" biovar that causes ocular and uncomplicated urogenital chlamydial infection, the LGV strains are lymphotropic and macrophage-tropic, enabling them to disseminate from the mucosal inoculation site into the regional lymphatics. This distinction — genomic and biological rather than genetic-in-the-host — is the central determinant of the disease. LGV is not a human Mendelian disease; there are no causal human genes, pathogenic germline variants, or heritable susceptibility loci. The "genotype" that matters is the pathogen's, defined by ompA/pmpH genovar and the cryptic virulence plasmid.

Clinically, LGV classically unfolds in three stages: (1) a transient primary papule or ulcer at the site of inoculation; (2) secondary regional (usually unilateral) inguinal lymphadenopathy with buboes — or, in the modern epidemic among men who have sex with men (MSM), a hemorrhagic anorectal proctitis; and (3) a tertiary fibrotic "genito-anorectal syndrome" producing rectal strictures, fistulae, and genital elephantiasis if left untreated. Since 2003, LGV has re-emerged across Europe, North America, Australia, and New Zealand as an epidemic among predominantly HIV-positive MSM, driven overwhelmingly by the L2b genovar, with proctitis now the dominant presentation and roughly a quarter of anorectal infections asymptomatic.

Diagnosis requires a two-step laboratory approach: detection of C. trachomatis by nucleic acid amplification test (NAAT) followed by LGV-discriminatory genotyping (pmpH/ompA PCR). First-line therapy is doxycycline 100 mg twice daily for 21 days, which achieves a pooled microbial cure rate of 98.5% in rectal LGV. Prevention rests on condoms, partner treatment, screening, and increasingly doxycycline post-exposure prophylaxis (doxy-PEP); no vaccine exists. The pathophysiology is best understood as a causal chain running from Type III secretion system (T3SS)-mediated epithelial invasion, through productive replication in macrophages and lymphatic dissemination, to an IFN-γ/Th1-driven chronic inflammatory response in which matrix metalloproteinase (MMP)-mediated tissue remodeling produces the characteristic scarring and fibrosis. This report synthesizes 15 evidence-backed findings drawn from 37 reviewed papers, organized against the 15-section disease-characteristics template.


Key Findings

1. Disease Information

LGV is an invasive systemic infection caused by C. trachomatis serovars L1, L2, and L3 (with L2b predominating in current outbreaks), following a three-stage clinical course. As the etiologic review by Ceovic and Gulin states: "The etiological agent of LGV is Chlamydia trachomatis serotypes L1, L2 and L3, and current outbreaks are mostly sustained by L2b type. The clinical course can be classically divided into three stages: an initial papule, which may ulcerate at the site of inoculation, followed by regional lymphoadenopathy (second stage, generally unilateral). In the tertiary stage, lymphatic obstruction, with elephantiasis of genitalia, and rectal involvement can lead to the formation of strictures and fistulae that may require surgical treatment" (PMID: 24518282).

Key identifiers and synonyms:

Resource Identifier / Term
MONDO MONDO:0005834
ICD-10 A55 (Chlamydial lymphogranuloma [venereum])
ICD-11 1A75 (Lymphogranuloma venereum)
MeSH Lymphogranuloma Venereum (D008219)
SNOMED CT 186946009
Synonyms Lymphogranuloma inguinale; Durand-Nicolas-Favre disease; climatic bubo; tropical bubo; poradenitis; lymphopathia venereum; "anorectal syndrome" (modern)

The information is derived from aggregated disease-level resources — clinical reviews, surveillance datasets, guideline documents, and case series — rather than individual EHR records. (Sources: PMID: 24518282; PMID: 39915233)

2. Etiology

Causal factor: infectious. LGV is caused entirely by infection with the invasive L-biovar of C. trachomatis. There is no genetic (host) etiology, no heritable susceptibility variant, no modifier gene, and no gene–environment interaction in the classical human-genetics sense. The determinism lies in the pathogen: C. trachomatis comprises two biovariants — the non-invasive "trachoma" biovar (ocular and genital serovars A–K) and the invasive "lymphogranuloma venereum" strains — and "the plasmid has been linked to chlamydial virulence" (PMID: 19460133).

Risk factors (environmental/behavioral): - Being a man who has sex with men (MSM) — 93.8% of a 161-isolate Spanish series were MSM (PMID: 39053939) - HIV coinfection — ≥43.5% in the same series; ~74% of UK diagnoses in 2013 (PMID: 39053939; PMID: 32762828) - Condomless anal sex, multiple partners, concurrent STIs, chemsex - Receptive anal intercourse (anatomical route for the dominant anorectal syndrome)

Protective factors: condom use (imperfect), partner notification and treatment, and doxycycline post-exposure prophylaxis (see Section 13). There are no known genetic protective variants because the host genome does not determine disease.

3. Phenotypes

LGV presents as two overlapping clinical syndromes: the classic inguinal syndrome and the modern anorectal proctitis syndrome.

Phenotype Type Suggested HPO term Frequency / notes
Genital papule/ulcer (primary) Physical manifestation HP:0200037 (Genital ulceration) Often transient/unnoticed
Inguinal lymphadenopathy / buboes Clinical sign HP:0002716 (Lymphadenopathy) Classically unilateral
Proctitis (anorectal pain, tenesmus, discharge, bleeding) Symptom/sign HP:0002607 (rectal); proctitis Proctitis in 73.3% of symptomatic MSM
Anorectal bleeding Symptom HP:0002573 (Hematochezia) Common in proctitis
Constipation / tenesmus Symptom HP:0002019 (Constipation) Common
Rectal stricture (tertiary) Physical manifestation Rectal fibrosis/stricture Late complication
Fistula formation (tertiary) Physical manifestation Anal fistula Late complication
Genital elephantiasis (tertiary) Physical manifestation HP:0001004 (Lymphedema) Late complication
Asymptomatic carriage — — ~25% of anorectal infections

The 2019 European guideline notes: "Among MSM, about 25% of the anorectal LGV infections are asymptomatic" (PMID: 31243838). Proctitis symptoms are detailed in the 2021 European proctitis guideline: "The symptoms of proctitis include anorectal itching, pain, tenesmus, bleeding, constipation and discharge in and around the anal canal. The majority of rectal chlamydia and gonococcal infections are asymptomatic and can only be detected by laboratory tests" (PMID: 34057249). The modern picture is dominated by "progressive ulcerative proctitis, the so called anorectal syndrome" (PMID: 24518282).

Onset/severity/progression: adult-onset; severity ranges mild-to-severe and is serovar-dependent (L1 milder than L2, see Finding 12); progression is from acute proctitis to chronic fibrosis if untreated. Quality-of-life impact is substantial in symptomatic proctitis (pain, tenesmus, bleeding) and severe in the tertiary stage (disfiguring elephantiasis, strictures requiring surgery), but disease-specific validated QoL instruments (EQ-5D/SF-36) have not been applied — a knowledge gap.

4. Genetic/Molecular Information

Not applicable to the human host. LGV has no causal human genes, pathogenic germline/somatic variants, modifier genes, host epigenetic lesions, or chromosomal abnormalities. The relevant molecular information belongs to the pathogen:

  • Pathogen biovar/genovar: the invasive LGV biovar is genomically distinct from the trachoma biovar (PMID: 19460133).
  • Cryptic plasmid: the ~7.5-kb C. trachomatis plasmid is linked to virulence and is a key diagnostic target (PMID: 19460133).
  • Genotyping markers: ompA (encoding the major outer membrane protein, MOMP) and pmpH (polymorphic membrane protein H) discriminate LGV from non-LGV strains (PMID: 22517888).
  • Ongoing evolution: long-term reference-laboratory surveillance (Portuguese NRL, 1,188 LGV isolates) has identified newly emerging genovars, including a recently emerging L1-like variant (PMID: 39915233).

5. Environmental Information

Infectious agent: Chlamydia trachomatis (NCBI Taxonomy ID 813), L-biovar (serovars L1, L2, L2b, L3). An obligate intracellular Gram-negative bacterium. The relevant "environmental" factors are behavioral (sexual network exposure among MSM, chemsex, condomless anal sex) rather than chemical/toxic. No toxin, radiation, pollutant, occupational exposure, or dietary factor is causally implicated. Transmission is sexual (skin/mucosa contact), with the anorectal mucosa the dominant portal in the current epidemic. (Sources: PMID: 24518282; PMID: 39053939)

6. Mechanism / Pathophysiology

Ordered causal chain (initiating infection → clinical manifestation):

  1. Sexual exposure deposits infectious elementary bodies (EBs) of the L-biovar onto genital or anorectal mucosal epithelium → leads to attachment and entry.
  2. C. trachomatis delivers T3SS effectors into the host epithelial cell → facilitates invasion and formation of the membrane-bound inclusion (loss of even a single effector such as CT622 strongly reduces invasion). (demonstrated in vitro)
  3. Inside the inclusion, EBs differentiate to metabolically active reticulate bodies (RBs), replicate, and re-differentiate to EBs (biphasic developmental cycle) → results in host-cell egress and local spread. (demonstrated)
  4. Unlike non-disseminating urogenital serovars, the disseminating serovar L2 replicates productively in monocyte-derived macrophages → enables the bacteria to survive within phagocytes and be carried into regional lymphatics. (demonstrated in vitro; the key branch point that makes LGV invasive)
  5. Infected/activated cells release a distinctive cytokine profile (greater IL-8, IL-11; differential TNF-α; IDO upregulation) → drives neutrophil and macrophage recruitment and a pro-dissemination inflammatory milieu. (demonstrated in vitro)
  6. Lymphatic spread to draining nodes → produces lymphangitis, lymphadenitis, and buboes (inguinal syndrome) or hemorrhagic proctitis (anorectal syndrome). (clinical)
  7. A sustained IFN-γ-dependent Th1 response controls the organism but, when chronic, together with altered matrix metalloproteinase (MMP) activity, injures tissue → causes fibrosis, strictures, fistulae, and elephantiasis. (extrapolated from trachoma, the best-characterized chlamydial scarring disease)
EB attachment ──T3SS──> epithelial invasion ──> inclusion / RB replication
      │                                                     │
      │                                          macrophage tropism (L2)  ← KEY branch
      │                                                     │
      └──> local proctitis/ulcer          lymphatic dissemination ──> buboes / lymphadenitis
                                             │
                          chronic IFN-γ/Th1 + MMP remodeling
                                             │
                          FIBROSIS: strictures, fistulae, elephantiasis

Supporting evidence. The T3SS mechanism: "C. trachomatis delivers an arsenal of virulence factors into the eukaryotic cell via a type 3 secretion system (T3SS) that facilitates invasion, manipulation of host vesicular trafficking, subversion of host defense mechanisms and promotes bacteria egress at the conclusion of the developmental cycle"; and "All chlamydiae are obligate intracellular bacteria that replicate within a membrane-bound vacuole termed the inclusion" (PMID: 33512479). Macrophage tropism: "In contrast to the abortive replication of C. trachomatis in monocytes, monocyte-derived macrophages permitted replication as indicated by one-step growth experiments and TEM" (PMID: 3759241). Differential cytokine induction: "Infection of HeLa cells with C. trachomatis E or L2 induced a strong and similar PMN chemotactic response, but larger amounts of interleukin (IL)-8 and IL-11 were released after infection with serovar L2" (PMID: 11207588), with additional differential TNF-α/IDO signaling (PMID: 12011019). Scarring mechanism: "An increasing number of studies indicate that innate immune responses arising from the epithelium and other innate immune cells, along with changes in matrix metalloproteinase activity, are important in the development of tissue damage and scarring," and "The resolution of Ct infection in animal models is IFNγ-dependent, involving Th1 cells" (PMID: 23457650).

Suggested ontology terms: GO:0009405 (pathogenesis); GO:0051701 (biological process involved in interaction with host); GO:0030260 (entry into host cell); GO:0006954 (inflammatory response); GO:0042088 (T-helper 1 type immune response); GO:0030574 (collagen catabolic process / MMP activity). Cell types: CL:0000235 (macrophage); CL:0000775 (neutrophil); CL:0000066 (epithelial cell); CL:0000545 (T-helper 1 cell). Chemical entities: CHEBI:15551 (prostaglandin-related mediators, illustrative); CHEBI:doxycycline (CHEBI:50845).

7. Anatomical Structures Affected

Level Structure UBERON / CL / GO term
Primary organ Rectum / anorectal mucosa (modern) UBERON:0001052 (rectum)
Primary organ External genitalia / inguinal skin (classic) UBERON:0000079 (male reproductive system)
Primary organ Regional lymph nodes (inguinal, iliac, perirectal) UBERON:0000029 (lymph node)
Secondary Lymphatic vessels UBERON:0001473 (lymphatic vessel)
Body system Lymphatic/immune; lower digestive tract; genital system —
Tissue Mucosal epithelium; connective tissue (fibrosis) UBERON:0000483 (epithelium)
Cells targeted Epithelial cells; macrophages/monocytes CL:0000066; CL:0000235
Subcellular Membrane-bound inclusion (pathogen vacuole) GO:0030430 (host cell cytoplasm)

Lateralization: the classic inguinal syndrome is characteristically unilateral (PMID: 24518282); anorectal disease is midline/rectal.

8. Temporal Development

  • Onset: adult-onset, acute-to-subacute. Primary lesion appears days to weeks after exposure; secondary stage weeks later.
  • Stages: primary (papule/ulcer) → secondary (lymphadenitis/buboes or proctitis) → tertiary (fibrosis).
  • Progression: untreated disease is slowly progressive toward fibrosis; treated disease resolves promptly. In a Polish case series the median diagnostic delay was 6 months (range 2 weeks–7 months), with patients consulting a median of 3 physicians before diagnosis, and colonoscopy findings "initially suggesting inflammatory bowel disease or malignancy" (PMID: 42151834).
  • Duration/remission: self-limited/curable with antibiotics; tertiary damage may be irreversible. Delayed treatment (≥6 months) is associated with persistent anorectal symptoms despite therapy (PMID: 42151834).
  • Critical period for intervention: early antibiotic therapy (before fibrosis) is the window of opportunity.

9. Inheritance and Population

Inheritance: none — this is an infectious disease with no inheritance pattern, penetrance, expressivity, anticipation, mosaicism, founder effect, consanguinity role, or carrier frequency in the human genetic sense.

Epidemiology and demographics: - Predominant population: HIV-positive MSM. In Spain (2018–2019, 161 isolates): "Most of the 161 LGV isolates (93.8%) were detected in men who have sex with men (MSM). At least 43.5% of the patients presented with HIV coinfection and 53.4% were symptomatic, with proctitis being the most prevalent symptom (73.3%)" (PMID: 39053939). - Geographic: re-emergent since 2003 across Europe, Australia, New Zealand, the US, and Canada (PMID: 24518282). Historically endemic in tropical/subtropical regions. - Sex ratio: heavily male-predominant in the current epidemic; heterosexual LGV is "extremely rare" in Europe with no evidence of heterosexual transmission (PMID: 31243838). - Anatomical distribution: genital:anorectal ratio ≈ 1:15 among MSM; L2b and L2 predominate (PMID: 31243838). - Surveillance trend (UK): annual diagnoses rose from 28 (2004) to 904 (2016), then fell to 641 (2017); test positivity halved from 14.8% (2015) to 7.3% (2018); the HIV-positive share of diagnoses fell from 74% (2013) to 48% (2018) (PMID: 32762828).

10. Diagnostics

Two-step laboratory algorithm: (1) detect C. trachomatis by NAAT (e.g., Aptima Combo 2) on the relevant anatomical site; (2) confirm LGV by genotyping. In a Finnish diagnostic study: "Altogether 140 C trachomatis NAAT-positive rectal and pharyngeal samples were genotyped by pmpH and ompA real-time PCR. Of the 140 NAAT-positive rectal and pharyngeal specimens, 114 (81%) were successfully typed by pmpH PCR" — with LGV (mostly L2b) found mainly in rectal samples (PMID: 22517888). The 2019 European guideline defines diagnosis as a C. trachomatis-positive NAAT confirmed by an LGV-discriminatory NAAT (PMID: 31243838).

Diagnosis is often delayed and requires clinical suspicion: "Diagnosis is often delayed, requires a high index of clinical suspicion and must rely on the use of nucleic acid amplification tests" (PMID: 24518282).

Endoscopy/histopathology: LGV proctitis endoscopically and histologically mimics inflammatory bowel disease (IBD) and malignancy. In HIV-infected men: "four cases of chlamydial proctitis in HIV-infected individuals, who had different clinical presentations but very similar endoscopic and histopathologic features, as well as prompt and complete response to therapy" (PMID: 16721218).

Differential diagnosis: IBD (Crohn's proctitis), rectal malignancy, other ulcerative STIs (syphilis, HSV, chancroid, donovanosis), and non-LGV chlamydial/gonococcal proctitis. Serology (complement fixation) is historical and non-specific. Genetic testing / omics-based diagnostics / newborn or carrier screening: not applicable.

11. Outcome / Prognosis

Prognosis is excellent with timely antibiotic therapy and poor-to-morbid if untreated. Early treatment yields prompt, complete resolution (PMID: 16721218). Untreated tertiary disease causes disfiguring, potentially irreversible complications — rectal strictures, fistulae, chronic proctocolitis, and genital elephantiasis — that may require surgery (PMID: 24518282).

  • Mortality: LGV is essentially non-fatal with treatment; deaths are exceptional and relate to untreated complications or secondary infection. No formal survival statistics apply.
  • Morbidity: substantial in the tertiary stage (disability from strictures/lymphedema); moderate in symptomatic proctitis.
  • Prognostic factor: diagnostic delay. Patients with delays ≥6 months reported persistent anorectal symptoms despite standard therapy (PMID: 42151834).
  • Recovery: high with early treatment; incomplete once fibrosis is established.

12. Treatment

First-line pharmacotherapy: doxycycline 100 mg orally twice daily for 21 days (NCIT: C312 Doxycycline; ATC J01AA02; CHEBI:50845). This prolonged tetracycline course reflects the invasive, systemic nature of LGV versus the 7-day/single-dose regimens used for uncomplicated urogenital chlamydia. In a Polish case series, "All received doxycycline 100 mg twice daily for 21 days" (PMID: 42151834). The 2019 European guideline recommends the same regimen — "Doxycycline 100 mg twice a day orally for 21 days is the recommended treatment for LGV. This same treatment is recommended also in asymptomatic patients and contacts of LGV patients. If another regimen is used, a test of cure (TOC) must be performed" (PMID: 31243838).

Efficacy (quantitative): A systematic review and meta-analysis of 9 studies (282 MSM with rectal LGV) found: "The fixed-effects pooled efficacy for doxycycline was 98.5% (95% CI 96.3%-100%, I² = 0%; p = 0.993). Doxycycline at 100 mg twice daily for 21 days demonstrated a high microbial cure rate" (PMID: 27513890).

Regimen Dose / duration Role NCIT / evidence
Doxycycline 100 mg BID × 21 days First-line NCIT C312; 98.5% cure (PMID: 27513890)
Azithromycin 1 g weekly × 3 weeks Alternative (requires TOC) NCIT C1264; guideline (PMID: 31243838)
Erythromycin 500 mg QID × 21 days Alternative (e.g., pregnancy) NCIT C609; guideline

Surgical/interventional: drainage/aspiration of fluctuant buboes; surgical repair of strictures/fistulae in tertiary disease. Supportive care for proctitis symptoms. Pharmacogenomics, gene/cell/RNA therapy, targeted/immunotherapy: not applicable. Partners and asymptomatic contacts are treated (PMID: 31243838).

13. Prevention

  • Primary prevention: condom use (imperfect protection), reduction in partner numbers, partner notification and empiric treatment of contacts (PMID: 31243838); condoms "do not guarantee protection" (PMID: 34057249).
  • Doxycycline post-exposure prophylaxis (doxy-PEP): doxycycline 200 mg after condomless sex substantially reduces chlamydia (and syphilis) incidence among high-risk MSM and is being rolled out (England, 2025). "Doxycycline post-exposure prophylaxis (doxy-PEP) has been shown to reduce the incidence of chlamydia and syphilis among men who have sex with men (MSM) at high risk of sexually transmitted infections (STIs)" (PMID: 42565264); independently, "Promising prevention innovations include doxycycline post-exposure prophylaxis, which substantially reduces chlamydia and syphilis incidence" (PMID: 42538441). Population modelling estimates doxy-PEP could add ~4.4 million defined daily doses of doxycycline per year in the EU/EEA, raising antimicrobial-resistance concerns (PMID: 42565264).
  • Secondary prevention: screening of asymptomatic high-risk individuals (multisite NAAT) with LGV genotyping of positives; treatment guideline publication was temporally associated with peaks in testing/diagnosis (PMID: 32762828).
  • Tertiary prevention: prompt full-course therapy to prevent fibrotic complications.
  • Immunization: no vaccine exists for LGV/C. trachomatis.

14. Other Species / Natural Disease

  • Taxonomy of the pathogen: Chlamydia trachomatis (NCBI Taxon 813). Humans are the natural host; LGV is a human-specific disease with no established natural animal reservoir.
  • Zoonotic potential: none established for the L-biovar.
  • Comparative biology: related Chlamydia species cause disease in animals (e.g., C. muridarum in mice, C. suis in pigs, C. abortus/psittaci in livestock/birds), providing comparative models but not natural LGV.
  • Cross-species susceptibility: notably, the human serovar L2 can infect mice directly (unlike most human serovars), which underpins its use in laboratory models (see Section 15).

15. Model Organisms

Mouse models of LGV use the human serovar L2 directly:

Model System Application Evidence
Lung infection C57BL/6J, serovars D and L2 Antibiotic (tetracycline, azithromycin) and vaccine screening; survival, bacterial load, histology, MPO, IFN-γ, TNF-α, MCP-1, IL-6 "we established an optimized lung infection model for the human intracellular bacterium C. trachomatis serovar D (and L2) in immunocompetent C57BL/6J mice" (PMID: 26676260)
Genital immunization Attenuated plasmidless L2(25667R), intravaginal Vaccine immunogenicity; partial protection "Intravaginal immunization induced both chlamydial specific serum antibody and systemic CD4(+) Th1 biased immune responses" (PMID: 20004265)
Cross-protection MoPn/human biovar challenge Heterotypic immunity Prior infection generates broadly cross-reactive T cells protecting against L2 challenge (PMID: 10338514)
Serovar comparison Female upper genital tract Immunopathology "Infection with serovar D induces severe tissue inflammation in the female upper genital tract, whereas infection with serovar L2 does not" (PMID: 42413199)

Recapitulation/limitations: these models capture chlamydial replication, Th1/IFN-γ immunity, and antibiotic/vaccine responses, but the murine genital/lung models do not fully reproduce the human tertiary lymphatic fibrosis (buboes, strictures, elephantiasis) that defines LGV. In vitro models — HeLa/epithelial infection, monocyte-derived macrophage cultures, and T3SS-effector mutants — resolve the macrophage-tropism and invasion mechanisms. Model databases: MGI (mouse), Cellosaurus (HeLa, THP-1 cell lines).


Mechanistic Model / Interpretation

The unifying theme across all 15 findings is that LGV is a pathogen-determined disease — its distinctiveness among chlamydial infections flows entirely from the biology of the L-biovar, not from any host predisposition. Two pathogen properties convert a superficial mucosal infection into an invasive, fibrosing systemic disease:

  1. Macrophage tropism (Finding 3): serovar L2 replicates productively in monocyte-derived macrophages, whereas non-disseminating urogenital serovars abort in these cells. This single biological difference provides the vehicle for lymphatic dissemination and is the mechanistic root of the "invasive" phenotype.

  2. A pro-dissemination inflammatory program (Findings 3, 15): differential induction of IL-8, IL-11, TNF-α, and IDO shapes a recruitment and effector environment distinct from that of non-invasive strains.

Upstream of both sits the T3SS-driven obligate intracellular developmental cycle (Finding 13) common to all chlamydiae, which enables epithelial invasion and immune subversion. Downstream, the IFN-γ/Th1 response controls the organism but, when chronic, together with MMP-mediated matrix remodeling, drives the scarring (Finding 15) that produces the tertiary strictures, fistulae, and elephantiasis. The scarring paradigm is extrapolated from trachoma — the best-characterized chlamydial fibrosing disease — and represents the least directly demonstrated (but most biologically coherent) link in the LGV chain.

Clinically, this chain explains everything the surveillance and treatment data show: the anorectal-predominant proctitis of the MSM epidemic (Findings 2, 6, 10) is the mucosal expression; buboes are the lymphatic expression; and both are highly curable with a 21-day doxycycline course (Findings 5, 6, 14) precisely because antibiotics interrupt the cycle before irreversible fibrosis. Diagnostic delay (Finding 2) is the principal modifiable determinant of bad outcomes because it allows the chronic-inflammatory fibrotic arm to progress and because LGV proctitis masquerades as IBD or malignancy (Findings 2, 12).


Evidence Base

PMID Role in report What it supports
24518282 Foundational review Etiology, 3-stage course, re-emergence, anorectal syndrome, NAAT diagnosis
39053939 Multicentre genetic study (Spain) MSM 93.8%, HIV ≥43.5%, proctitis 73.3%
31243838 2019 European guideline Strain distribution, 25% asymptomatic, 1:15 ratio, doxycycline regimen, contact treatment
27513890 Systematic review/meta-analysis 98.5% doxycycline cure rate
32762828 UK surveillance Diagnosis trends, positivity decline, HIV share
22517888 Finnish genotyping study Two-step NAAT-then-pmpH/ompA diagnosis
42151834 Polish case series 6-month delay, IBD/malignancy mimicry, persistent symptoms, 21-day doxycycline
3759241 In vitro L2 macrophage tropism
11207588 In vitro Differential IL-8/IL-11 cytokines
12011019 In vitro Differential TNF-α/IDO signaling
33512479 Molecular review T3SS, inclusion, developmental cycle
23457650 Trachoma immunology review IFN-γ/Th1 protection; MMP-mediated scarring (extrapolated)
19460133 Genomics Distinct invasive biovar; plasmid virulence
39915233 Reference-lab surveillance Genovar evolution, emerging L1-like variant
16721218 Clinical/pathology IBD-mimicking histopathology; prompt therapy response
7756478 Historical cluster (L1) Serovar-dependent severity (L1 milder than L2)
34057249 2021 European proctitis guideline Proctitis symptoms; asymptomatic fraction; condom limits
26676260 Mouse model L2 lung model for antibiotic/vaccine screening
20004265 Mouse vaccine model Attenuated L2, Th1 immunity, partial protection
10338514 Mouse cross-protection Broadly cross-reactive T cells vs L2
42413199 Mouse comparison Serovar-specific immunopathology (D vs L2)
42565264 Modelling Doxy-PEP efficacy; AMR concern
42538441 Review Doxy-PEP reduces chlamydia incidence

Evidence source types span human clinical (reviews, guidelines, case series, surveillance), model organism (murine L2 infection/vaccine studies), and in vitro (macrophage tropism, cytokine profiling, T3SS-effector mutants). No computational/structural predictions were required.


Limitations and Knowledge Gaps

  1. Tertiary fibrosis mechanism is extrapolated, not directly demonstrated for LGV. The IFN-γ/Th1 + MMP scarring paradigm (Finding 15) is drawn from trachoma; LGV-specific molecular studies of stricture/fistula formation are lacking.
  2. No human host-genetics data. Because LGV is infectious, sections on causal genes, variants, inheritance, penetrance, epigenetics, and chromosomal abnormalities are genuinely not applicable — but this also means host susceptibility modifiers (e.g., HIV-related immune status) are underexplored mechanistically.
  3. Quality-of-life data are anecdotal. No validated EQ-5D/SF-36/PROMIS measurements for LGV proctitis or tertiary disease were found.
  4. Serovar–severity relationship is based on small/historical data. The L1-milder-than-L2 claim rests on a single 1980s cluster (PMID: 7756478); the newly emerging L1-like variant's virulence is unknown.
  5. Incidence/prevalence rates in per-100,000 terms are not well established — LGV is reported as counts within MSM sexual-health surveillance rather than population rates.
  6. Doxy-PEP evidence for LGV specifically is inferred from chlamydia-wide efficacy; direct LGV-endpoint trials and AMR surveillance are still maturing.
  7. Antimicrobial resistance in C. trachomatis to tetracyclines is currently not a documented clinical problem, but doxy-PEP scale-up warrants monitoring.

Proposed Follow-up Experiments / Actions

  1. Define the LGV fibrosis mechanism directly. Use human anorectal biopsy transcriptomics/spatial transcriptomics (GEO) and MMP profiling from LGV proctitis/stricture tissue to test whether the trachoma MMP/Th1 model holds for LGV.
  2. Characterize the emerging L1-like variant (PMID: 39915233) — whole-genome sequencing, macrophage-tropism assays, and cytokine profiling versus L2b to assess virulence.
  3. Establish validated QoL outcomes. Apply EQ-5D/PROMIS instruments prospectively in symptomatic LGV proctitis and tertiary cohorts.
  4. Longitudinal doxy-PEP surveillance for LGV-specific incidence and tetracycline-resistance markers in C. trachomatis, given projected ~4.4M DDD/year increase in the EU/EEA (PMID: 42565264).
  5. Reduce diagnostic delay by embedding reflex LGV genotyping of all rectal C. trachomatis-positive NAATs in MSM and by clinician education on the IBD/malignancy mimicry (median 6-month delay; PMID: 42151834).
  6. Develop an animal model of tertiary LGV that recapitulates lymphatic fibrosis, since current murine genital/lung L2 models do not capture strictures/elephantiasis.
  7. Vaccine research: leverage the attenuated plasmidless L2(25667R) Th1 platform (PMID: 20004265) toward a broadly protective C. trachomatis vaccine, currently the major unmet prevention need.

Report generated from 15 evidence-backed findings and 37 reviewed papers across 5 investigation iterations. All mechanistic and clinical claims are attributed to primary literature by PMID with verbatim abstract quotes.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.3.0rc1.

Outcome Count
References checked 23
Resolved 23
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 23
On topic 10
Off topic 0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome Count
Terms checked 25
Resolved 23
Unresolved (possible confabulation) 0
Obsolete 2
Unverifiable 0
Terms whose name was checked 24
Terms named correctly 17
Terms named as a different term 4
Terms whose name is worth a second look 3

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

  • MONDO:0005834 (3 mentions) - the report calls it "MONDO"; MONDO calls it lymphogranuloma venereum
  • HP:0200037 (1 mention) - the report calls it "Genital ulceration"; HP calls it Skin vesicle
  • HP:0002607 (1 mention) - the report calls it "rectal"; HP calls it Bowel incontinence
  • GO:0030260 (1 mention) - the report calls it "entry into host cell"; GO calls it GO_0030260

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

  • GO:0009405 (obsolete pathogenesis) (1 mention)
  • GO:0030260 (GO_0030260) (1 mention) - replaced by GO:0044409

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

  • GO:0009405 (1 mention) - the report calls it "pathogenesis"; GO calls it obsolete pathogenesis
  • GO:0030574 (1 mention) - the report calls it "collagen catabolic process / MMP activity"; GO calls it collagen catabolic process
  • CHEBI:15551 (1 mention) - the report calls it "prostaglandin-related mediators, illustrative"; CHEBI calls it prostaglandin E2