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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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.
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.
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.
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
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.
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)
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.
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.
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:
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)
Ordered causal chain (initiating infection → clinical manifestation):
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).
| 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.
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).
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.
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).
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).
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).
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:
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.
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).
| 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.
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.
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.
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 |
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 venereumHP:0200037 (1 mention) - the report calls it "Genital ulceration"; HP calls it Skin vesicleHP:0002607 (1 mention) - the report calls it "rectal"; HP calls it Bowel incontinenceGO:0030260 (1 mention) - the report calls it "entry into host cell"; GO calls it GO_0030260These 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:0044409The 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 pathogenesisGO:0030574 (1 mention) - the report calls it "collagen catabolic process / MMP activity"; GO calls it collagen catabolic processCHEBI:15551 (1 mention) - the report calls it "prostaglandin-related mediators, illustrative"; CHEBI calls it prostaglandin E2