⚙

Pathophysiology

5

Oropharyngeal Fusobacterium infection

Acute pharyngotonsillar infection is the usual initiating focus. F. necrophorum, and less often odontogenic streptococci or other anaerobes, invade from the upper aerodigestive tract into adjacent deep neck spaces.

neutrophil CL:0000775

response to bacterium GO:0009617 ⚠ ABNORMAL inflammatory response GO:0006954 ⚠ ABNORMAL

oropharynx UBERON:0001729 palatine tonsil UBERON:0002373

Downstream

Internal jugular septic thrombophlebitis Deep neck spread from the oropharyngeal focus seeds the lateral pharyngeal and carotid-sheath region, where the hallmark internal-jugular septic thrombus forms.

Fusobacterial leukotoxin immune evasion The oropharyngeal F. necrophorum population elaborates leukotoxin and other virulence factors that mediate immune evasion.

Sore throat Acute pharyngotonsillar infection produces the antecedent sore throat.

Show evidence (2 references)

PMID:41517763 SUPPORT Human Clinical

"Lemierre syndrome (LS) is a rare but life-threatening complication of acute oropharyngeal infections."

Places the usual initiating lesion in an acute oropharyngeal infection.

PMID:42517948 SUPPORT Human Clinical

"Although the classic form is usually associated with oropharyngeal infection and Fusobacterium necrophorum, odontogenic and non-Fusobacterium cases have also been reported."

Supports the classic F. necrophorum/oropharyngeal source and acknowledges the odontogenic and non-Fusobacterium etiologic edge cases.

Fusobacterial leukotoxin immune evasion

F. necrophorum virulence is dominated by leukotoxin, with endotoxin and other secreted products also implicated. Bovine leukocyte experiments show that purified leukotoxin activates polymorphonuclear leukocytes at low concentrations, induces apoptotic/programmed death at higher concentrations, and produces necrotic death at very high concentrations; this mechanism is strong model support for immune evasion but the human internal-jugular thrombus-initiation step remains inferred.

neutrophil CL:0000775

apoptotic process GO:0006915 ⚠ ABNORMAL inflammatory response GO:0006954 ⚠ ABNORMAL

toxin activity GO:0090729

Downstream

Internal jugular septic thrombophlebitis Leukotoxin-mediated immune evasion is thought to permit the anaerobic invasion that seeds the internal-jugular septic thrombus. The human thrombus-initiation step is inferred from bovine leukotoxin experiments rather than directly demonstrated.

Show evidence (2 references)

PMID:8711893 SUPPORT Other

"Among these, leukotoxin and endotoxin are believed to be more important than other toxins in overcoming the host's defence mechanisms to establish the infection."

A veterinary review identifies leukotoxin and endotoxin as the major F. necrophorum virulence factors that overcome host defense.

PMID:12117974 SUPPORT In Vitro

"The ability of F. necrophorum leukotoxin to modulate the host immune system by its toxicity, including cellular activation of PMNs and apoptosis-mediated killing of phagocytes and immune effector cells, represents a potentially important mechanism of its pathogenesis."

Purified leukotoxin work in bovine leukocytes provides direct experimental support for leukotoxin-mediated phagocyte activation and killing.

Internal jugular septic thrombophlebitis

Infection reaching the deep neck spaces triggers a septic thrombus in the internal jugular vein. F. necrophorum hemagglutinin, hemolysin, proteases, adhesin, and endothelial injury are plausible contributors to coagulation, but direct human proof of platelet-driven thrombus initiation is limited.

endothelial cell CL:0000115 platelet CL:0000233

blood coagulation GO:0007596 ⚠ ABNORMAL inflammatory response GO:0006954 ⚠ ABNORMAL

internal jugular vein UBERON:0001586

Downstream

Pulmonary septic embolization Fragments and bacteria from the infected jugular thrombus embolize hematogenously, most often to the lungs.

Show evidence (2 references)

PMID:39840169 SUPPORT Human Clinical

"The diagnosis of Lemierre's syndrome is typically confirmed through the identification of thrombophlebitis of the internal jugular vein on radiographic imaging and the isolation of anaerobic bacteria in blood cultures."

Defines internal jugular thrombophlebitis as the diagnostic vascular lesion in Lemierre syndrome.

PMID:16701574 SUPPORT Other

"Several toxins or secreted products, such as leukotoxin, endotoxin, hemolysin, hemagglutinin, proteases, and adhesin, etc., have been implicated as virulence factors."

Supports the set of F. necrophorum virulence factors that may contribute to the human septic-thrombophlebitis step, which remains partly inferred.

Pulmonary septic embolization

Septic emboli seeded from the internal jugular thrombus disseminate to the lungs, producing the typical respiratory branch of Lemierre syndrome with septic pulmonary emboli, pleuritic pain, hemoptysis, and severe pleural or parenchymal complications in some patients.

neutrophil CL:0000775

response to bacterium GO:0009617 ⚠ ABNORMAL inflammatory response GO:0006954 ⚠ ABNORMAL

lung UBERON:0002048

Downstream

Septic pulmonary embolism Emboli lodging in the pulmonary vasculature produce septic pulmonary emboli, the dominant metastatic complication.

Hemoptysis Pulmonary septic emboli can produce hemoptysis.

Systemic bacteremia and sepsis Bacteremia and metastatic emboli progress to systemic sepsis and its complications.

Show evidence (2 references)

PMID:20570017 SUPPORT Human Clinical

"RESULTS: We had 6 patients with LS. 5 males. Median age: 25 years old. All with sore throat and pulmonary embolisms."

A six-patient clinical series illustrates the sore-throat and pulmonary embolism pairing that follows internal jugular septic thrombosis.

PMID:42127655 SUPPORT Human Clinical

"Computed tomography (CT) imaging was utilized in 89.5% of cases, and was most useful for detecting thrombosis of the internal jugular vein and septic emboli."

In pediatric Lemierre syndrome, CT commonly identifies the co-occurring vascular thrombosis and septic emboli.

Systemic bacteremia and sepsis

Ongoing bacteremia from the infected internal-jugular thrombus and metastatic septic emboli drives systemic sepsis, thrombocytopenia, and, in a subset, septic shock and intensive-care-level illness.

neutrophil CL:0000775

inflammatory response GO:0006954 ⚠ ABNORMAL

Downstream

Sepsis Systemic infection manifests as sepsis in most patients.

Thrombocytopenia Systemic invasive infection produces thrombocytopenia on admission.

Septic shock A subset of septic patients progress to septic shock.

Fever Systemic infection produces the near-universal fever.

Show evidence (1 reference)

PMID:31843654 SUPPORT Human Clinical

"Among patients with LS 72/96 (75%) had thrombocytopenia on admission, 86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104 (43%) needed intensive care."

Quantifies the major systemic complications among 104 Swedish Lemierre syndrome patients.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

7

Blood 2

Septic pulmonary embolism HP:0033639

Show evidence (1 reference)

PMID:40224244 SUPPORT Human Clinical

"Lemierre syndrome is a rare and life-threatening condition that typically arises secondary to an oropharyngeal infection, progressing to thrombosis of the internal jugular vein and dissemination of septic emboli, most commonly to the lungs."

States that septic emboli disseminate most commonly to the lungs after the internal jugular thrombus.

Thrombocytopenia FREQUENT HP:0001873

Show evidence (1 reference)

PMID:31843654 SUPPORT Human Clinical

"Among patients with LS 72/96 (75%) had thrombocytopenia on admission, 86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104 (43%) needed intensive care."

Reports thrombocytopenia on admission in 75% of evaluable Swedish Lemierre syndrome cases.

Cardiovascular 1

Septic shock OCCASIONAL HP:0031273

Severity: SEVERE

Show evidence (1 reference)

PMID:31843654 SUPPORT Human Clinical

"Among patients with LS 72/96 (75%) had thrombocytopenia on admission, 86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104 (43%) needed intensive care."

Reports septic shock in 18% of 104 Swedish Lemierre syndrome cases.

Immune 1

Sepsis VERY_FREQUENT HP:0100806

Show evidence (1 reference)

PMID:31843654 SUPPORT Human Clinical

"Among patients with LS 72/96 (75%) had thrombocytopenia on admission, 86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104 (43%) needed intensive care."

Reports sepsis in 83% of 104 Swedish Lemierre syndrome cases.

Metabolism 1

Fever VERY_FREQUENT HP:0001945

Show evidence (1 reference)

PMID:42127655 SUPPORT Human Clinical

"Fever was the most common presenting symptom in 92% of patients, and F. necrophorum was the predominantly identified organism in 78.3% of patients."

Reports fever in 92% of 143 pediatric Lemierre syndrome cases.

Respiratory 1

Hemoptysis HP:0002105

Show evidence (1 reference)

PMID:20570017 SUPPORT Human Clinical

"One of the 6 developed acute renal failure, another one hemoptysis, and another a hydropneumothorax which was drained."

Reports hemoptysis as a pulmonary complication in a Lemierre syndrome case series.

Constitutional 1

Sore throat Pharyngalgia HP:0033050

Show evidence (1 reference)

PMID:20570017 SUPPORT Human Clinical

"RESULTS: We had 6 patients with LS. 5 males. Median age: 25 years old. All with sore throat and pulmonary embolisms."

Documents sore throat at presentation in a Lemierre syndrome case series.

💊

Medical Actions

3

Prolonged anaerobe-active antibiotic therapy

Action: Antibiotic Therapy NCIT:C15620

Agent: metronidazole CHEBI:6909

Empiric and targeted treatment uses prolonged broad-spectrum antibacterial therapy that covers anaerobes, commonly a beta-lactam/beta-lactamase inhibitor or a third-generation cephalosporin combined with metronidazole; carbapenems are an alternative broad-spectrum regimen.

Mechanism Target:

Oropharyngeal Fusobacterium infection — Anaerobe-active antibiotics kill or suppress the causative oropharyngeal F. necrophorum population and other susceptible bacterial pathogens.

Pulmonary septic embolization — Systemic therapy treats bacteria disseminated in septic emboli after they seed the lungs.

Show evidence (2 references)

PMID:40224244 SUPPORT Human Clinical

"Immediate treatment involves broad-spectrum antibiotic therapy, often utilizing a third-generation cephalosporin or a beta-lactam in combination with metronidazole."

Describes the common broad-spectrum plus metronidazole antibiotic strategy for Lemierre syndrome.

PMID:20570017 SUPPORT Human Clinical

"All the patients were managed with antibiotics against anaerobes, carbapenems in 3 cases."

Supports anaerobe-active antibiotic coverage and includes carbapenems as a used broad-spectrum option.

Source control drainage and salvage internal jugular surgery

Action: Incision and Drainage NCIT:C38067

Drainage of abscesses supplies local source control. Internal jugular vein ligation or excision is a rare salvage option for persistent septicemia or progressive embolization despite antimicrobial therapy and source control.

Mechanism Target:

Oropharyngeal Fusobacterium infection — Drainage reduces the local bacterial burden in drainable tonsillar, odontogenic, or deep-neck abscesses.

Internal jugular septic thrombophlebitis — Internal jugular surgery is a rare salvage maneuver that removes the uncontrolled infected thrombus when medical therapy and source control fail.

Show evidence (2 references)

PMID:39257960 SUPPORT Human Clinical

"Surgical treatment includes abscess drainage, while IJV ligation and excision are reserved for nonresponders to medical treatment."

Describes abscess drainage as surgical source control and internal jugular surgery as a non-routine option after medical nonresponse.

PMID:42517948 SUPPORT Human Clinical

"IJV excision remains controversial and should not be considered routine treatment for Lemierre's syndrome."

Clarifies that internal jugular excision is a salvage treatment rather than routine management.

Selected adjunctive anticoagulation

Action: Anticoagulation Therapy NCIT:C63341

Anticoagulation is considered only as an adjunct for selected thrombus patterns or high-risk cases because its indications in Lemierre syndrome remain controversial.

Mechanism Target:

Internal jugular septic thrombophlebitis — Adjunctive anticoagulation targets thrombus propagation and is considered for selected extensive or high-risk thrombosis.

Show evidence (1 reference)

PMID:32909436 SUPPORT Human Clinical

"Anticoagulation in LS is a clinical controversy because the thromboembolic events have rarely led to significant complications; thrombi typically resolve independently, and concerns for bleeding risks are well founded; however, this review indicates both the efficacy and safety of anticoagulation."

Supports modeling anticoagulation as a selected, debated adjunct rather than universal treatment.

🔬

Diagnosis

2

Contrast imaging and anaerobic blood culture

Diagnosis is confirmed by demonstrating internal jugular vein thrombophlebitis on cross-sectional imaging together with isolation of anaerobic bacteria from blood cultures.

computed tomography NCIT:C17204

Show evidence (1 reference)

PMID:39840169 SUPPORT Human Clinical

"The diagnosis of Lemierre's syndrome is typically confirmed through the identification of thrombophlebitis of the internal jugular vein on radiographic imaging and the isolation of anaerobic bacteria in blood cultures."

Defines imaging of internal jugular thrombophlebitis plus anaerobic blood culture as the confirmatory diagnostic combination.

Targeted next-generation sequencing

Targeted next-generation sequencing with metagenomic capture can rapidly detect F. necrophorum and support early diagnosis.

targeted next-generation sequencing NCIT:C101293

Show evidence (1 reference)

PMID:41517763 SUPPORT PRIMARY RESULT Human Clinical

"FN was rapidly detected and LS was diagnosed using targeted next-generation sequencing (tNGS) combined with metagenomics capture (MetaCAP)."

A case report shows targeted NGS with metagenomic capture rapidly identifying F. necrophorum for early Lemierre diagnosis.

📈

Progression

1

Outcome

Despite its severity, contemporary 30-day mortality in Lemierre syndrome is low with treatment.

Show evidence (1 reference)

PMID:31843654 SUPPORT Human Clinical

"30-day mortality in LS was 2/104 (2%)."

Reports a low 30-day mortality (2/104, 2%) in the Swedish Lemierre cohort.

📊

Prevalence

1

Sweden 2010-2017 (invasive Fusobacterium necrophorum infection)

Annual Incidence 0.5 per 100,000 (0.29–0.5) per year 1–9 per 1,000,000 per year

Nationwide Swedish incidence of invasive F. necrophorum infection rose from 2.9 to 5.0 cases per million per year (0.29-0.5 per 100,000); Lemierre syndrome was 35% (104/300) of these invasive cases.

Show evidence (1 reference)

PMID:31843654 SUPPORT Human Clinical

"The incidence increased from 2.9 to 5.0 cases/million/year from 2010-13 to 2014-17"

Reports the nationwide incidence of invasive F. necrophorum infection, of which Lemierre syndrome is a subset.

🦠

Infectious Agent

1

Fusobacterium necrophorum

Fusobacterium necrophorum is the dominant anaerobic bacterial cause of Lemierre syndrome; a 143-case pediatric systematic review identified it in 78.3% of reported patients.

Fusobacterium necrophorum NCBITaxon:859

Show evidence (1 reference)

PMID:42127655 SUPPORT Human Clinical

"Fever was the most common presenting symptom in 92% of patients, and F. necrophorum was the predominantly identified organism in 78.3% of patients."

A pediatric systematic review identifies F. necrophorum as the predominant organism among 143 Lemierre syndrome cases.

{ }

Source YAML

click to show

name: Lemierre Syndrome
creation_date: "2026-09-25T18:58:41Z"
category: Infectious Disease
description: >-
  Lemierre syndrome is an acquired, life-threatening complication of head and
  neck infection in which Fusobacterium necrophorum or another oropharyngeal
  bacterial pathogen invades from the tonsillopharyngeal or odontogenic source
  to cause internal jugular vein septic thrombophlebitis, bacteremia, and
  metastatic septic emboli, most often in the lungs. It primarily affects
  adolescents and young adults and presents with fever, sore throat, septic
  pulmonary emboli, thrombocytopenia, sepsis, and sometimes septic shock.
disease_term:
  term:
    id: MONDO:0015306
    label: Lemierre syndrome
  preferred_term: Lemierre Syndrome
parents:
- bacterial infectious disease with sepsis
- commensal bacterial infectious disease
synonyms:
- Necrobacillosis
- Lemierre postanginal sepsis
- Postanginal sepsis
- Septic phlebitis of the internal jugular vein
infectious_agent:
- name: Fusobacterium necrophorum
  description: >-
    Fusobacterium necrophorum is the dominant anaerobic bacterial cause of
    Lemierre syndrome; a 143-case pediatric systematic review identified it in
    78.3% of reported patients.
  infectious_agent_term:
    preferred_term: Fusobacterium necrophorum
    term:
      id: NCBITaxon:859
      label: Fusobacterium necrophorum
  evidence:
  - reference: PMID:42127655
    reference_title: "Pediatric Lemierre's syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fever was the most common presenting symptom in 92% of patients, and F.
      necrophorum was the predominantly identified organism in 78.3% of patients.
    explanation: >-
      A pediatric systematic review identifies F. necrophorum as the predominant
      organism among 143 Lemierre syndrome cases.
pathophysiology:
- name: Oropharyngeal Fusobacterium infection
  description: >-
    Acute pharyngotonsillar infection is the usual initiating focus. F.
    necrophorum, and less often odontogenic streptococci or other anaerobes,
    invade from the upper aerodigestive tract into adjacent deep neck spaces.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: response to bacterium
    modifier: ABNORMAL
    term:
      id: GO:0009617
      label: response to bacterium
  - preferred_term: inflammatory response
    modifier: ABNORMAL
    term:
      id: GO:0006954
      label: inflammatory response
  locations:
  - preferred_term: oropharynx
    term:
      id: UBERON:0001729
      label: oropharynx
  - preferred_term: palatine tonsil
    term:
      id: UBERON:0002373
      label: palatine tonsil
  evidence:
  - reference: PMID:41517763
    reference_title: >-
      Early diagnosis of Lemierre syndrome using targeted next-generation
      sequencing combined with metagenomics capture: A case report and literature
      review.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Lemierre syndrome (LS) is a rare but life-threatening complication of acute
      oropharyngeal infections.
    explanation: >-
      Places the usual initiating lesion in an acute oropharyngeal infection.
  - reference: PMID:42517948
    reference_title: >-
      Excision of the internal jugular vein in uncontrolled Lemierre's syndrome:
      a case report and literature review.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Although the classic form is usually associated with oropharyngeal
      infection and Fusobacterium necrophorum, odontogenic and non-Fusobacterium
      cases have also been reported.
    explanation: >-
      Supports the classic F. necrophorum/oropharyngeal source and acknowledges
      the odontogenic and non-Fusobacterium etiologic edge cases.
  downstream:
  - target: Internal jugular septic thrombophlebitis
    description: >-
      Deep neck spread from the oropharyngeal focus seeds the lateral pharyngeal
      and carotid-sheath region, where the hallmark internal-jugular septic
      thrombus forms.
    evidence:
    - reference: PMID:39840169
      reference_title: Early Radiographic Warning Signs of Impending Lemierre's Syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        It is characterized by the extension of infection into the lateral
        pharyngeal spaces, leading to subsequent septic thrombophlebitis of the
        internal jugular vein(s).
      explanation: >-
        Describes the anatomic progression from head and neck infection to
        internal jugular septic thrombophlebitis.
  - target: Fusobacterial leukotoxin immune evasion
    description: >-
      The oropharyngeal F. necrophorum population elaborates leukotoxin and other
      virulence factors that mediate immune evasion.
  - target: Sore throat
    description: >-
      Acute pharyngotonsillar infection produces the antecedent sore throat.
- name: Fusobacterial leukotoxin immune evasion
  description: >-
    F. necrophorum virulence is dominated by leukotoxin, with endotoxin and
    other secreted products also implicated. Bovine leukocyte experiments show
    that purified leukotoxin activates polymorphonuclear leukocytes at low
    concentrations, induces apoptotic/programmed death at higher concentrations,
    and produces necrotic death at very high concentrations; this mechanism is
    strong model support for immune evasion but the human internal-jugular
    thrombus-initiation step remains inferred.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: apoptotic process
    modifier: ABNORMAL
    term:
      id: GO:0006915
      label: apoptotic process
  - preferred_term: inflammatory response
    modifier: ABNORMAL
    term:
      id: GO:0006954
      label: inflammatory response
  molecular_functions:
  - preferred_term: toxin activity
    term:
      id: GO:0090729
      label: toxin activity
  chemical_entities:
  - preferred_term: lipopolysaccharide
    term:
      id: CHEBI:16412
      label: lipopolysaccharide
  evidence:
  - reference: PMID:8711893
    reference_title: >-
      Fusobacterium necrophorum infections: virulence factors, pathogenic
      mechanism and control measures.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Among these, leukotoxin and endotoxin are believed to be more important
      than other toxins in overcoming the host's defence mechanisms to establish
      the infection.
    explanation: >-
      A veterinary review identifies leukotoxin and endotoxin as the major
      F. necrophorum virulence factors that overcome host defense.
  - reference: PMID:12117974
    reference_title: >-
      Fusobacterium necrophorum leukotoxin induces activation and apoptosis of
      bovine leukocytes.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The ability of F. necrophorum leukotoxin to modulate the host immune system
      by its toxicity, including cellular activation of PMNs and
      apoptosis-mediated killing of phagocytes and immune effector cells,
      represents a potentially important mechanism of its pathogenesis.
    explanation: >-
      Purified leukotoxin work in bovine leukocytes provides direct experimental
      support for leukotoxin-mediated phagocyte activation and killing.
  downstream:
  - target: Internal jugular septic thrombophlebitis
    description: >-
      Leukotoxin-mediated immune evasion is thought to permit the anaerobic
      invasion that seeds the internal-jugular septic thrombus. The human
      thrombus-initiation step is inferred from bovine leukotoxin experiments
      rather than directly demonstrated.
- name: Internal jugular septic thrombophlebitis
  description: >-
    Infection reaching the deep neck spaces triggers a septic thrombus in the
    internal jugular vein. F. necrophorum hemagglutinin, hemolysin, proteases,
    adhesin, and endothelial injury are plausible contributors to coagulation,
    but direct human proof of platelet-driven thrombus initiation is limited.
  cell_types:
  - preferred_term: endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  - preferred_term: platelet
    term:
      id: CL:0000233
      label: platelet
  biological_processes:
  - preferred_term: blood coagulation
    modifier: ABNORMAL
    term:
      id: GO:0007596
      label: blood coagulation
  - preferred_term: inflammatory response
    modifier: ABNORMAL
    term:
      id: GO:0006954
      label: inflammatory response
  locations:
  - preferred_term: internal jugular vein
    term:
      id: UBERON:0001586
      label: internal jugular vein
  evidence:
  - reference: PMID:39840169
    reference_title: Early Radiographic Warning Signs of Impending Lemierre's Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of Lemierre's syndrome is typically confirmed through the
      identification of thrombophlebitis of the internal jugular vein on
      radiographic imaging and the isolation of anaerobic bacteria in blood
      cultures.
    explanation: >-
      Defines internal jugular thrombophlebitis as the diagnostic vascular
      lesion in Lemierre syndrome.
  - reference: PMID:16701574
    reference_title: "Fusobacterium necrophorum infections in animals: pathogenesis and pathogenic mechanisms."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Several toxins or secreted products, such as leukotoxin, endotoxin,
      hemolysin, hemagglutinin, proteases, and adhesin, etc., have been
      implicated as virulence factors.
    explanation: >-
      Supports the set of F. necrophorum virulence factors that may contribute
      to the human septic-thrombophlebitis step, which remains partly inferred.
  downstream:
  - target: Pulmonary septic embolization
    description: >-
      Fragments and bacteria from the infected jugular thrombus embolize
      hematogenously, most often to the lungs.
    evidence:
    - reference: PMID:40224244
      reference_title: >-
        Lemierre's syndrome secondary to fusobacterium necrophorum in an
        immunocompetent patient: A rare case.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Lemierre syndrome is a rare and life-threatening condition that typically
        arises secondary to an oropharyngeal infection, progressing to thrombosis
        of the internal jugular vein and dissemination of septic emboli, most
        commonly to the lungs.
      explanation: >-
        Connects the oropharyngeal infection, internal-jugular thrombosis, and
        dominant lung septic-embolus destination.
- name: Pulmonary septic embolization
  description: >-
    Septic emboli seeded from the internal jugular thrombus disseminate to the
    lungs, producing the typical respiratory branch of Lemierre syndrome with
    septic pulmonary emboli, pleuritic pain, hemoptysis, and severe pleural or
    parenchymal complications in some patients.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: response to bacterium
    modifier: ABNORMAL
    term:
      id: GO:0009617
      label: response to bacterium
  - preferred_term: inflammatory response
    modifier: ABNORMAL
    term:
      id: GO:0006954
      label: inflammatory response
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:20570017
    reference_title: "[Lemierre syndrome: several clinical features of \"a forgotten disease\"]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      RESULTS: We had 6 patients with LS. 5 males. Median age: 25 years old. All
      with sore throat and pulmonary embolisms.
    explanation: >-
      A six-patient clinical series illustrates the sore-throat and pulmonary
      embolism pairing that follows internal jugular septic thrombosis.
  - reference: PMID:42127655
    reference_title: "Pediatric Lemierre's syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Computed tomography (CT) imaging was utilized in 89.5% of cases, and was
      most useful for detecting thrombosis of the internal jugular vein and
      septic emboli.
    explanation: >-
      In pediatric Lemierre syndrome, CT commonly identifies the co-occurring
      vascular thrombosis and septic emboli.
  downstream:
  - target: Septic pulmonary embolism
    description: >-
      Emboli lodging in the pulmonary vasculature produce septic pulmonary emboli,
      the dominant metastatic complication.
  - target: Hemoptysis
    description: >-
      Pulmonary septic emboli can produce hemoptysis.
  - target: Systemic bacteremia and sepsis
    description: >-
      Bacteremia and metastatic emboli progress to systemic sepsis and its
      complications.
- name: Systemic bacteremia and sepsis
  description: >-
    Ongoing bacteremia from the infected internal-jugular thrombus and metastatic
    septic emboli drives systemic sepsis, thrombocytopenia, and, in a subset,
    septic shock and intensive-care-level illness.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: inflammatory response
    modifier: ABNORMAL
    term:
      id: GO:0006954
      label: inflammatory response
  evidence:
  - reference: PMID:31843654
    reference_title: >-
      Invasive infections with Fusobacterium necrophorum including Lemierre's
      syndrome: an 8-year Swedish nationwide retrospective study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among patients with LS 72/96 (75%) had thrombocytopenia on admission,
      86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104
      (43%) needed intensive care.
    explanation: >-
      Quantifies the major systemic complications among 104 Swedish Lemierre
      syndrome patients.
  downstream:
  - target: Sepsis
    description: Systemic infection manifests as sepsis in most patients.
  - target: Thrombocytopenia
    description: Systemic invasive infection produces thrombocytopenia on admission.
  - target: Septic shock
    description: A subset of septic patients progress to septic shock.
  - target: Fever
    description: Systemic infection produces the near-universal fever.
phenotypes:
- category: Constitutional
  name: Fever
  frequency: VERY_FREQUENT
  description: >-
    Fever is the most common presenting feature of pediatric Lemierre syndrome,
    reported in 92% of cases in a systematic review.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: PMID:42127655
    reference_title: "Pediatric Lemierre's syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fever was the most common presenting symptom in 92% of patients, and F.
      necrophorum was the predominantly identified organism in 78.3% of patients.
    explanation: >-
      Reports fever in 92% of 143 pediatric Lemierre syndrome cases.
- category: Head And Neck
  name: Sore throat
  description: >-
    Pharyngalgia or sore throat marks the antecedent oropharyngeal phase of
    classic Lemierre syndrome.
  phenotype_term:
    preferred_term: Pharyngalgia
    term:
      id: HP:0033050
      label: Pharyngalgia
  evidence:
  - reference: PMID:20570017
    reference_title: "[Lemierre syndrome: several clinical features of \"a forgotten disease\"]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      RESULTS: We had 6 patients with LS. 5 males. Median age: 25 years old. All
      with sore throat and pulmonary embolisms.
    explanation: >-
      Documents sore throat at presentation in a Lemierre syndrome case series.
- category: Respiratory
  name: Septic pulmonary embolism
  description: >-
    Septic pulmonary emboli are the dominant metastatic complication after
    internal jugular vein septic thrombophlebitis.
  phenotype_term:
    preferred_term: Septic pulmonary embolism
    term:
      id: HP:0033639
      label: Septic pulmonary embolism
  evidence:
  - reference: PMID:40224244
    reference_title: >-
      Lemierre's syndrome secondary to fusobacterium necrophorum in an
      immunocompetent patient: A rare case.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Lemierre syndrome is a rare and life-threatening condition that typically
      arises secondary to an oropharyngeal infection, progressing to thrombosis
      of the internal jugular vein and dissemination of septic emboli, most
      commonly to the lungs.
    explanation: >-
      States that septic emboli disseminate most commonly to the lungs after the
      internal jugular thrombus.
- category: Respiratory
  name: Hemoptysis
  description: >-
    Pulmonary septic emboli can produce hemoptysis as part of the lower
    respiratory presentation.
  phenotype_term:
    preferred_term: Hemoptysis
    term:
      id: HP:0002105
      label: Hemoptysis
  evidence:
  - reference: PMID:20570017
    reference_title: "[Lemierre syndrome: several clinical features of \"a forgotten disease\"]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      One of the 6 developed acute renal failure, another one hemoptysis, and
      another a hydropneumothorax which was drained.
    explanation: >-
      Reports hemoptysis as a pulmonary complication in a Lemierre syndrome
      case series.
- category: Hematologic
  name: Thrombocytopenia
  frequency: FREQUENT
  description: >-
    Thrombocytopenia is a frequent acute laboratory abnormality during invasive
    F. necrophorum Lemierre syndrome.
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: PMID:31843654
    reference_title: >-
      Invasive infections with Fusobacterium necrophorum including Lemierre's
      syndrome: an 8-year Swedish nationwide retrospective study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among patients with LS 72/96 (75%) had thrombocytopenia on admission,
      86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104
      (43%) needed intensive care.
    explanation: >-
      Reports thrombocytopenia on admission in 75% of evaluable Swedish Lemierre
      syndrome cases.
- category: Infectious
  name: Sepsis
  frequency: VERY_FREQUENT
  description: >-
    Internal jugular septic thrombophlebitis and metastatic embolization
    commonly progress to sepsis.
  phenotype_term:
    preferred_term: Sepsis
    term:
      id: HP:0100806
      label: Sepsis
  evidence:
  - reference: PMID:31843654
    reference_title: >-
      Invasive infections with Fusobacterium necrophorum including Lemierre's
      syndrome: an 8-year Swedish nationwide retrospective study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among patients with LS 72/96 (75%) had thrombocytopenia on admission,
      86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104
      (43%) needed intensive care.
    explanation: >-
      Reports sepsis in 83% of 104 Swedish Lemierre syndrome cases.
- category: Cardiovascular
  name: Septic shock
  frequency: OCCASIONAL
  description: >-
    A subset of patients progress from sepsis to septic shock and
    intensive-care-level illness.
  phenotype_term:
    preferred_term: Shock
    term:
      id: HP:0031273
      label: Shock
    severity: SEVERE
  evidence:
  - reference: PMID:31843654
    reference_title: >-
      Invasive infections with Fusobacterium necrophorum including Lemierre's
      syndrome: an 8-year Swedish nationwide retrospective study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among patients with LS 72/96 (75%) had thrombocytopenia on admission,
      86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104
      (43%) needed intensive care.
    explanation: >-
      Reports septic shock in 18% of 104 Swedish Lemierre syndrome cases.
treatments:
- name: Prolonged anaerobe-active antibiotic therapy
  description: >-
    Empiric and targeted treatment uses prolonged broad-spectrum antibacterial
    therapy that covers anaerobes, commonly a beta-lactam/beta-lactamase
    inhibitor or a third-generation cephalosporin combined with metronidazole;
    carbapenems are an alternative broad-spectrum regimen.
  treatment_term:
    preferred_term: Antibiotic Therapy
    term:
      id: NCIT:C15620
      label: Antibiotic Therapy
    therapeutic_agent:
    - preferred_term: metronidazole
      term:
        id: CHEBI:6909
        label: metronidazole
  target_mechanisms:
  - target: Oropharyngeal Fusobacterium infection
    description: >-
      Anaerobe-active antibiotics kill or suppress the causative oropharyngeal
      F. necrophorum population and other susceptible bacterial pathogens.
  - target: Pulmonary septic embolization
    description: >-
      Systemic therapy treats bacteria disseminated in septic emboli after they
      seed the lungs.
  evidence:
  - reference: PMID:40224244
    reference_title: >-
      Lemierre's syndrome secondary to fusobacterium necrophorum in an
      immunocompetent patient: A rare case.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Immediate treatment involves broad-spectrum antibiotic therapy, often
      utilizing a third-generation cephalosporin or a beta-lactam in combination
      with metronidazole.
    explanation: >-
      Describes the common broad-spectrum plus metronidazole antibiotic
      strategy for Lemierre syndrome.
  - reference: PMID:20570017
    reference_title: "[Lemierre syndrome: several clinical features of \"a forgotten disease\"]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All the patients were managed with antibiotics against anaerobes,
      carbapenems in 3 cases.
    explanation: >-
      Supports anaerobe-active antibiotic coverage and includes carbapenems as
      a used broad-spectrum option.
- name: Source control drainage and salvage internal jugular surgery
  description: >-
    Drainage of abscesses supplies local source control. Internal jugular vein
    ligation or excision is a rare salvage option for persistent septicemia or
    progressive embolization despite antimicrobial therapy and source control.
  treatment_term:
    preferred_term: Incision and Drainage
    term:
      id: NCIT:C38067
      label: Incision and Drainage
  target_mechanisms:
  - target: Oropharyngeal Fusobacterium infection
    description: >-
      Drainage reduces the local bacterial burden in drainable tonsillar,
      odontogenic, or deep-neck abscesses.
  - target: Internal jugular septic thrombophlebitis
    description: >-
      Internal jugular surgery is a rare salvage maneuver that removes the
      uncontrolled infected thrombus when medical therapy and source control
      fail.
  evidence:
  - reference: PMID:39257960
    reference_title: "Lemierre Syndrome with Extensive Thrombosis: A Unique Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Surgical treatment includes abscess drainage, while IJV ligation and
      excision are reserved for nonresponders to medical treatment.
    explanation: >-
      Describes abscess drainage as surgical source control and internal
      jugular surgery as a non-routine option after medical nonresponse.
  - reference: PMID:42517948
    reference_title: >-
      Excision of the internal jugular vein in uncontrolled Lemierre's syndrome:
      a case report and literature review.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      IJV excision remains controversial and should not be considered routine
      treatment for Lemierre's syndrome.
    explanation: >-
      Clarifies that internal jugular excision is a salvage treatment rather
      than routine management.
- name: Selected adjunctive anticoagulation
  description: >-
    Anticoagulation is considered only as an adjunct for selected thrombus
    patterns or high-risk cases because its indications in Lemierre syndrome
    remain controversial.
  treatment_term:
    preferred_term: Anticoagulation Therapy
    term:
      id: NCIT:C63341
      label: Anticoagulation Therapy
  target_mechanisms:
  - target: Internal jugular septic thrombophlebitis
    description: >-
      Adjunctive anticoagulation targets thrombus propagation and is considered
      for selected extensive or high-risk thrombosis.
  evidence:
  - reference: PMID:32909436
    reference_title: >-
      Anticoagulation Strategies in the Management of Lemierre Syndrome: A
      Systematic Review of the Literature.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Anticoagulation in LS is a clinical controversy because the thromboembolic
      events have rarely led to significant complications; thrombi typically
      resolve independently, and concerns for bleeding risks are well founded;
      however, this review indicates both the efficacy and safety of
      anticoagulation.
    explanation: >-
      Supports modeling anticoagulation as a selected, debated adjunct rather
      than universal treatment.
diagnosis:
- name: Contrast imaging and anaerobic blood culture
  description: >-
    Diagnosis is confirmed by demonstrating internal jugular vein
    thrombophlebitis on cross-sectional imaging together with isolation of
    anaerobic bacteria from blood cultures.
  diagnosis_term:
    preferred_term: computed tomography
    term:
      id: NCIT:C17204
      label: Computed Tomography
  evidence:
  - reference: PMID:39840169
    reference_title: Early Radiographic Warning Signs of Impending Lemierre's Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of Lemierre's syndrome is typically confirmed through the
      identification of thrombophlebitis of the internal jugular vein on
      radiographic imaging and the isolation of anaerobic bacteria in blood
      cultures.
    explanation: >-
      Defines imaging of internal jugular thrombophlebitis plus anaerobic blood
      culture as the confirmatory diagnostic combination.
- name: Targeted next-generation sequencing
  description: >-
    Targeted next-generation sequencing with metagenomic capture can rapidly
    detect F. necrophorum and support early diagnosis.
  diagnosis_term:
    preferred_term: targeted next-generation sequencing
    term:
      id: NCIT:C101293
      label: Next Generation Sequencing
  evidence:
  - reference: PMID:41517763
    reference_title: >-
      Early diagnosis of Lemierre syndrome using targeted next-generation
      sequencing combined with metagenomics capture: A case report and literature
      review.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      FN was rapidly detected and LS was diagnosed using targeted
      next-generation sequencing (tNGS) combined with metagenomics capture
      (MetaCAP).
    explanation: >-
      A case report shows targeted NGS with metagenomic capture rapidly
      identifying F. necrophorum for early Lemierre diagnosis.
prevalence:
- population: Sweden 2010-2017 (invasive Fusobacterium necrophorum infection)
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BAND_1_9_PER_1000000
  rate_per_100000: 0.5
  rate_low: 0.29
  rate_high: 0.5
  rate_denominator: POPULATION_PER_YEAR
  notes: >-
    Nationwide Swedish incidence of invasive F. necrophorum infection rose from
    2.9 to 5.0 cases per million per year (0.29-0.5 per 100,000); Lemierre
    syndrome was 35% (104/300) of these invasive cases.
  evidence:
  - reference: PMID:31843654
    reference_title: >-
      Invasive infections with Fusobacterium necrophorum including Lemierre's
      syndrome: an 8-year Swedish nationwide retrospective study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The incidence increased from 2.9 to 5.0 cases/million/year from 2010-13 to
      2014-17
    explanation: >-
      Reports the nationwide incidence of invasive F. necrophorum infection, of
      which Lemierre syndrome is a subset.
progression:
- phase: Outcome
  notes: >-
    Despite its severity, contemporary 30-day mortality in Lemierre syndrome is
    low with treatment.
  evidence:
  - reference: PMID:31843654
    reference_title: >-
      Invasive infections with Fusobacterium necrophorum including Lemierre's
      syndrome: an 8-year Swedish nationwide retrospective study.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "30-day mortality in LS was 2/104 (2%)."
    explanation: >-
      Reports a low 30-day mortality (2/104, 2%) in the Swedish Lemierre cohort.

📚

References & Deep Research

Deep Research

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Evaluations and curation notes (1)

Create: Lemierre Syndrome · 2026-09-25T19:20:40Z · View source

Created a new Lemierre syndrome entry from OpenScientist deep research. Curated F. necrophorum infectious-agent identity, the oropharyngeal infection to internal-jugular septic thrombophlebitis to pulmonary septic embolization chain, acute sepsis phenotypes, and antibiotic/source-control/selected-anticoagulation treatment records. Ran OpenScientist preflight and manually confirmed the MONDO identity after the gene-based preflight skipped because this infectious disease has no human causal gene.

OpenScientist ▸

Lemierre Syndrome: A Comprehensive Disease Characteristics Report

openscientist-autonomous 22 citations 2026-09-25T12:14:15.271832

Lemierre Syndrome: A Comprehensive Disease Characteristics Report

Disease: Lemierre Syndrome (LS) MONDO ID: MONDO:0015306 Category: Infectious Disease Report type: Disease knowledge-base entry (multi-iteration autonomous literature synthesis) Evidence base: 27 PubMed sources; predominantly human clinical case series, systematic reviews, and national registry studies, supplemented by veterinary/in-vitro mechanistic studies. No patient-level data files provided.

Summary

Lemierre syndrome is a rare, life-threatening, acquired infectious disease defined by septic thrombophlebitis of the internal jugular vein (IJV) that develops as a complication of an oropharyngeal (usually pharyngotonsillar) infection, with subsequent metastatic septic emboli that spread most often to the lungs. It is caused predominantly by the Gram-negative obligate anaerobe Fusobacterium necrophorum, which is identified in roughly 78% of cases in systematic reviews. The classic causal triad is: (1) oropharyngeal infection → (2) IJV septic thrombophlebitis → (3) metastatic septic emboli. The syndrome characteristically strikes previously healthy adolescents and young adults (median age ~15–20 years) with a male predominance.

Critically, Lemierre syndrome is NOT a genetic disease. No causal human gene, Mendelian inheritance pattern, penetrance/expressivity behavior, heritable variant, or founder effect exists for this condition. It is an acquired complication of bacterial infection. Consequently, the many sections of the research template dealing with causal genes, pathogenic variants, ACMG variant classification, gnomAD allele frequencies, genetic testing (WGS/WES/panels/karyotyping), carrier screening, genetic counseling, and inheritance are Not Applicable, and this report explicitly documents them as such rather than fabricating content. The etiologically relevant "genome" here is that of the pathogen: the F. necrophorum leukotoxin operon and associated virulence factors.

Prognosis is favorable with prompt treatment but the illness remains serious. Modern mortality is approximately 5% (versus up to 80% in the pre-antibiotic era, when death commonly occurred within 7–15 days), but complication rates are high—sepsis in ~83%, thrombocytopenia in ~75%, ICU admission in ~43%, and septic shock in ~18% of hospitalized patients. Management centers on prolonged anaerobe-active antibiotic therapy (a beta-lactam/beta-lactamase inhibitor or third-generation cephalosporin combined with metronidazole, or a carbapenem) plus source control; adjunctive anticoagulation remains controversial and of unproven benefit. With appropriate therapy the disease is self-limited/curable (no chronic or relapsing course), and thrombus resolves or recanalizes in ~78% of cases on follow-up imaging. A key evidence gap is that the platelet-aggregation/thrombus-initiation step of human pathophysiology is inferred from in-vitro and ruminant data rather than directly demonstrated in humans.

Key Findings

Finding 1 — Definition and dominant pathogen

Lemierre syndrome is septic thrombophlebitis of the internal jugular vein caused predominantly by Fusobacterium necrophorum following an oropharyngeal infection. A systematic review of 143 pediatric cases found F. necrophorum in 78.3% of patients, with fever as the most common presenting symptom (92%); CT imaging was used in 89.5% of cases and was most useful for detecting IJV thrombosis and septic emboli (PMID: 42127655): "F. necrophorum was the predominantly identified organism in 78.3% of patients." The defining pathology is captured directly in the literature: "It is characterized by septic thrombophlebitis of the internal jugular vein and subsequent metastatic abscess formation. The most common causative pathogen of LS is Fusobacterium necrophorum" (PMID: 41517763). The classic clinical sequence—oropharyngeal infection → IJV septic thrombophlebitis → metastatic septic emboli (most often to the lung)—organizes the entire disease concept.

Ontology anchors: MONDO:0015306 (Lemierre syndrome); UBERON:0001584 (internal jugular vein); NCBI:txid859 (Fusobacterium necrophorum); HP:0001945 (Fever).

Finding 2 — Epidemiology: rare, rising, young, male-predominant

Lemierre syndrome is rare but with rising incidence, currently estimated at roughly 1–10 cases per million per year (a commonly cited central estimate is ~3.6 per million). A Swedish nationwide study (2010–2017, n = 300 invasive F. necrophorum infections) documented that the incidence of invasive F. necrophorum infection increased from 2.9 to 5.0 cases/million/year (p = 0.001), that 104/300 (35%) of these patients developed Lemierre syndrome, and that the median age of LS patients was 20 years (PMID: 31843654): "The incidence increased from 2.9 to 5.0 cases/million/year from 2010-13 to 2014-17 (p 0.001)." A population-level incidence estimate of "3.6 cases per million population" is reported in PMID: 42576194. The disease has been termed "the forgotten disease" because it became rare after the introduction of antibiotics but has been re-emerging since the 2000s. It preferentially affects previously healthy adolescents and young adults with a male predominance.

Ontology anchors: age of onset — adolescent/young adult (HP:0011462, Young adult onset).

Finding 3 — Severe systemic illness; ~5% modern mortality

Lemierre syndrome causes severe systemic illness with high complication rates. In the Swedish cohort of 104 LS patients, 75% (72/96) had thrombocytopenia on admission, 83% (86/104) had sepsis, 18% (19/104) developed septic shock, and 43% (45/104) required intensive care (PMID: 31843654): "72/96 (75%) had thrombocytopenia on admission, 86/104 (83%) had sepsis, 19/104 (18%) developed septic shock and 45/104 (43%) needed intensive [care]." Modern mortality is approximately 5%, rising with diagnostic delay, whereas in the pre-antibiotic era the disease "was often characterized by a fatal course within 7-15 days with a mortality rate that could reach up to 80% of cases" (PMID: 40265142). Long-term complications were reported in 4.2% of pediatric cases (PMID: 42127655).

Complication	Frequency (Swedish LS cohort, n=104)
Sepsis	83% (86/104)
Thrombocytopenia on admission	75% (72/96)
ICU admission	43% (45/104)
Septic shock	18% (19/104)

Ontology anchors: HP:0100806 (Sepsis); HP:0001873 (Thrombocytopenia); HP:0031273 (Septic shock).

Finding 4 — Leukotoxin is the major virulence factor

F. necrophorum leukotoxin is the major virulence factor driving Lemierre pathophysiology, with endotoxin (LPS), hemolysin, hemagglutinin, proteases, and adhesins contributing. Reviews conclude that "leukotoxin and endotoxin are believed to be more important than other toxins in overcoming the host's defence mechanisms to establish the infection" (PMID: 8711893). Mechanistically, purified leukotoxin activates polymorphonuclear leukocytes (PMNs) and induces their apoptosis/necrosis: "The ability of F. necrophorum leukotoxin to modulate the host immune system by its toxicity, including cellular activation of PMNs and apoptosis-mediated killing of phagocytes and immune effector cells, represents a potentially important mechanism of its pathogenesis" (PMID: 12117974). Subspecies necrophorum (biotype A) is more virulent than subspecies funduliforme (biotype B) (PMID: 16701574).

Ontology anchors: GO:0006954 (inflammatory response); GO:0006915 (apoptotic process); GO:0090729 (toxin activity); CL:0000775 (neutrophil); CHEBI:16412 (lipopolysaccharide).

Finding 5 — Diagnosis: contrast-enhanced CT + anaerobic blood cultures + molecular methods

Diagnosis relies on contrast-enhanced CT of the neck and chest (demonstrating IJV thrombosis and septic emboli) plus anaerobic blood cultures, with molecular methods increasingly used. In the pediatric systematic review, "Computed tomography (CT) imaging was utilized in 89.5% of cases, and was most useful for detecting thrombosis of the internal jugular vein and septic emboli" (PMID: 42127655). The two-pronged confirmatory standard is stated directly: "The diagnosis of Lemierre's syndrome is typically confirmed through the identification of thrombophlebitis of the internal jugular vein on radiographic imaging and the isolation of anaerobic bacteria in blood cultures" (PMID: 39840169). Contrast-enhanced cervicothoracic CT is the workhorse (PMID: 40224244). Because anaerobic cultures may be slow or negative, molecular diagnostics—16S rDNA sequencing/targeted PCR (PMID: 31843654) and targeted next-generation sequencing combined with metagenomic capture—enable rapid F. necrophorum detection (PMID: 41517763). Common laboratory abnormalities include thrombocytopenia, elevated CRP, and leukocytosis.

Ontology anchors: diagnostic imaging — contrast-enhanced CT; LOINC-mappable labs (CRP, platelet count, WBC); anaerobic blood culture.

Finding 6 — Treatment: prolonged anaerobe-active antibiotics + source control; anticoagulation controversial

Treatment centers on prolonged anaerobe-active antibiotics with source control. First-line therapy is described as: "Immediate treatment involves broad-spectrum antibiotic therapy, often utilizing a third-generation cephalosporin or a beta-lactam in combination with metronidazole" (PMID: 40224244). Carbapenems are also reported as a good therapeutic choice (PMID: 20570017). Anticoagulation remains controversial: a systematic review found parenteral anticoagulation used initially in 12/14 patients and DOAC outcomes similar to warfarin, but concluded that "the thromboembolic events have rarely led to significant complications; thrombi typically resolve independently, and concerns for bleeding risks are well founded" (PMID: 32909436). Anticoagulation was used in 62.2% of pediatric cases and surgery in 6% (PMID: 42127655). Surgical options include abscess drainage, with IJV ligation/excision reserved for non-responders (PMID: 39257960).

Treatment element	Detail	NCIT-type mapping
Beta-lactam/BLI (e.g., ampicillin-sulbactam, piperacillin-tazobactam)	Empiric anaerobe coverage	Antibacterial agent
Third-gen cephalosporin + metronidazole	Common first-line combination	Metronidazole (NCIT antibacterial)
Carbapenem (e.g., meropenem)	Alternative broad-spectrum choice	Carbapenem antibiotic
Anticoagulation (LMWH/DOAC/warfarin)	Selected high-risk cases; controversial	Anticoagulant therapy
Abscess drainage / IJV ligation-excision	Source control; salvage for non-responders	Surgical procedure

Ontology anchors: CHEBI:6077 (metronidazole); NCIT antibacterial/anticoagulant/surgical-procedure branches.

Finding 7 — Anatomy and phenotypes

The primary source is oropharyngeal (tonsillitis/pharyngitis, peritonsillar abscess), with odontogenic and otogenic (otitis media/mastoiditis) sources also described (PMID: 42517948, PMID: 12109395). Septic thrombophlebitis localizes to the internal jugular vein, and septic emboli disseminate preferentially to the lungs (pulmonary emboli/cavitary consolidations); in one series "All [patients had] sore throat and pulmonary embolisms" (PMID: 20570017). Metastatic and contiguous spread can reach the intracranial venous sinuses, orbit, joints, and pleura (empyema), and can be complicated by DIC and ARDS. An otogenic pediatric series documented that "Internal jugular vein thrombosis occurred in 80%, sigmoid sinus thrombosis in 60%, and cavernous sinus thrombosis in 30%" (PMID: 42141231). Common phenotypes include fever (92%), sore throat, neck pain/swelling, chest pain, hemoptysis, and dyspnea.

Level	Structure	UBERON / ontology term
Primary source	Oropharynx / palatine tonsil	UBERON:0001729 (oropharynx); UBERON:0002373 (palatine tonsil)
Primary vascular lesion	Internal jugular vein	UBERON:0001584
Dominant embolic target	Lung	UBERON:0002048
Intracranial extension	Sigmoid/cavernous venous sinuses	UBERON:0006459 (sigmoid sinus); UBERON:0004024 (cavernous sinus)
Body systems	Cardiovascular, respiratory, digestive/upper aerodigestive	—

Phenotype ontology anchors: HP:0001945 (Fever); HP:0002098 (Respiratory distress/dyspnea); HP:0002105 (Hemoptysis); HP:0100749 (Chest pain).

Finding 8 — Not genetic; expanding etiologic spectrum ("Lemierre-like syndrome")

Lemierre syndrome is not a genetic disease—no causal human gene, inheritance pattern, or heritable variant is described; it is an acquired complication of bacterial infection. Beyond classic F. necrophorum, cases arise from viridans group streptococci (often odontogenic; PMID: 42517948) and other anaerobes/streptococci. "Lemierre-like syndrome" (LLS) from non-oropharyngeal sources is increasingly recognized: "In contrast to classic Lemierre syndrome, sources of infection are not related to oropharyngeal infections, as are frequent soft tissue infections. In recent years, Staphylococcus aureus has been identified as an emergent pathogen that causes this syndrome. The mortality rate of LLS caused by this pathogen is approximately 16%" (PMID: 38363930). An "incomplete Lemierre's syndrome" variant is also defined: "Incomplete Lemierre's syndrome is a bacterial oropharyngeal infection, complicated by septic emboli to end organs, but without thrombophlebitis of the internal jugular vein" (PMID: 42286749). Risk factors are environmental/infectious: preceding pharyngotonsillitis, young age, and restricted/inappropriate antibiotic use for sore throat (PMID: 12109395).

Finding 9 — Natural animal disease and models (necrobacillosis)

F. necrophorum causes major naturally occurring disease in animals (necrobacillosis), which informs pathogenesis and prevention. It is a normal alimentary-tract commensal and opportunistic pathogen; "Of these, bovine liver abscesses and foot rot are of significant concern to the cattle industry" (PMID: 16701574). Liver abscesses arise when ruminal organisms enter the portal circulation secondary to ruminal acidosis. A randomized, blinded feedlot field trial demonstrated that a F. necrophorum bacterin reduced liver abscesses (odds ratio 0.27, P = 0.05) and footrot (OR 0.18, P = 0.03) in forage-fed cattle: "The odds that a vaccinated animal in the ALF group would have an A or A+ liver abscess at slaughter were less than 1/3 the odds that an unvaccinated animal" (PMID: 16363327). Isolates have also been recovered from the respiratory tract of white-tailed deer (Odocoileus virginianus) (PMID: 24590666). Leukotoxin virulence is studied primarily in bovine leukocyte/PMN in-vitro models (PMID: 12117974).

Taxonomy anchors: Bos taurus (NCBI:txid9913, cattle); Odocoileus virginianus (NCBI:txid9874, white-tailed deer); Fusobacterium necrophorum (NCBI:txid859).

Finding 10 — Prevention is secondary; no human vaccine

Prevention of Lemierre syndrome is secondary—early recognition and appropriate anaerobe-active antibiotic treatment of F. necrophorum pharyngitis—because no human vaccine or established primary chemoprophylaxis exists. Cost-effectiveness modeling suggests that "examining throat swabs from 15- to 24-year-olds for F. necrophorum followed by antibiotic treatment will probably be less costly than most other life-saving medical interventions, with a median cost of US$8,795 per QALY saved" (PMID: 22886057); only a 20–25% reduction in LS/PTA incidence would be required for cost-effectiveness. The main preventable drivers are diagnostic delay and inadequate antibiotic coverage; restricted or inappropriate antibiotic use (macrolides, narrow cephalosporins, to which F. necrophorum may be resistant) for pharyngitis is linked to rising incidence (PMID: 12109395, PMID: 20570017). Early radiographic recognition of impending LS enables timely intervention (PMID: 39840169).

Finding 11 — Temporal course: acute onset, rapid progression, self-limited with treatment

The temporal course is acute/subacute onset days after pharyngitis, rapid progression to sepsis, but self-limited with treatment (no chronic/relapsing course). The classic sequence is antecedent sore throat/pharyngitis, then within roughly one week the development of IJV thrombophlebitis and septic emboli. Imaging can capture striking speed: "Within four days, the infection rapidly progressed to complete occlusion of the internal jugular vein with pulmonary septic emboli" (PMID: 39840169). The pre-antibiotic natural history was often fatal within 7–15 days (PMID: 40265142). With appropriate therapy the illness is self-limited/curable—there is no lifelong or relapsing course—though recovery requires prolonged (weeks-long) antibiotics; thrombus resolves or recanalizes in ~78% of cases on follow-up imaging: "Thrombosis resolved or recanalized in 78% of cases on follow-up imaging" (PMID: 42141231). Onset is typically in previously healthy adolescents/young adults (median ~15–20 years); it is not congenital.

Finding 12 — Evidence gap: human thrombus-initiation step is inferred

The platelet-aggregation/thrombus-initiation step in human Lemierre pathophysiology is inferred, not directly demonstrated. Reviews list hemagglutinin and platelet-aggregating/hemolytic activity among F. necrophorum virulence factors implicated in thrombus formation, but candidly note that "The pathogenic mechanism of F. necrophorum is complex and not well defined" (PMID: 16701574, PMID: 8711893). Direct experimental demonstration of F. necrophorum-driven platelet aggregation causing IJV thrombosis in humans was not identified in this review; the strongest mechanistic data (leukotoxin-mediated leukocyte apoptosis) derive from ruminant/in-vitro systems (PMID: 12117974). No human transcriptomic/proteomic/metabolomic disease signatures are available.

Mechanistic Model / Interpretation

Ordered causal chain (initiating lesion → clinical manifestation)

Oropharyngeal colonization/infection by F. necrophorum (usually acute tonsillitis/pharyngitis or peritonsillar abscess; alternatively odontogenic or otogenic foci) leads to local mucosal invasion. (Well supported — PMID 42127655, 12109395.)
Local invasion results in direct/contiguous spread into the peritonsillar and parapharyngeal soft tissues and the adjacent carotid sheath. (Well supported anatomically — PMID 42517948.)
Bacterial leukotoxin and endotoxin (LPS) activate polymorphonuclear leukocytes and then kill phagocytes by apoptosis/necrosis, enabling immune evasion and unchecked local proliferation. (Mechanism demonstrated in vitro/ruminant models — PMID 12117974, 8711893.)
Endothelial injury plus procoagulant activity (hemagglutinin, platelet-aggregating and hemolytic factors) is inferred to lead to septic thrombophlebitis of the internal jugular vein. (INFERRED in humans — the platelet-aggregation/thrombus-initiation step is not directly demonstrated; PMID 16701574, 8711893, Finding 12.)
IJV septic thrombophlebitis results in bacteremia and shedding of infected thrombus fragments → metastatic septic emboli, most commonly to the lungs (cavitary consolidations, empyema), and less often to joints, intracranial venous sinuses, and orbit. (Well supported — PMID 20570017, 42141231.)
Systemic bacteremia and embolization lead to sepsis (~83%), thrombocytopenia (~75%), and, in severe cases, septic shock (~18%), DIC, and ARDS. (Well supported — PMID 31843654, 42517948.)
Branch: with prompt anaerobe-active antibiotics ± source control, the process is self-limited, thrombus recanalizes (~78%), and mortality is ~5%; without timely therapy, the historical course was fatal within 7–15 days (mortality up to 80%). (Well supported — PMID 40265142, 42141231, 39840169.)

 Oropharyngeal infection (F. necrophorum)
    │  leukotoxin + endotoxin → PMN killing / immune evasion
    ▼
 Contiguous spread to carotid sheath
    │  endothelial injury + (inferred) platelet aggregation
    ▼
 Internal jugular vein SEPTIC THROMBOPHLEBITIS ──► bacteremia
    │                                          │
    ▼                                          ▼
 Septic emboli → LUNGS (dominant)          Sepsis / thrombocytopenia
   also: joints, sinuses, orbit, pleura     → septic shock / DIC / ARDS
    │
    ▼
   ┌───────────────┬───────────────────────────┐
   │ Treated       │ Untreated (historical)     │
   │ ~5% mortality │ ~80% mortality, 7–15 days  │
   │ 78% recanalize│                            │
   └───────────────┴───────────────────────────┘

Upstream vs downstream: The pathogen's leukotoxin/endotoxin-mediated immune subversion is the upstream driver; IJV thrombosis is the pivotal intermediate lesion; septic emboli and multi-organ failure are downstream consequences. Cell types / processes: neutrophils (CL:0000775) and other phagocytes are killed by leukotoxin (GO:0006915 apoptotic process; GO:0006954 inflammatory response); vascular endothelium (CL:0000115) and platelets (CL:0000233) participate in thrombus formation (GO:0007596 blood coagulation). Because the human disease is an acquired infection, there are no host causal genes, pathways (Wnt/MAPK/mTOR/PI3K-AKT), epigenetic changes, or heritable protein dysfunctions to annotate; the relevant molecular apparatus is bacterial.

Not Applicable / Not Available Sections (explicit)

Because Lemierre syndrome is an acquired infectious disease with no genetic etiology, the following template items are Not Applicable and should be recorded as such in the knowledge base:

Template section	Status	Rationale
Causal genes / OMIM gene entries	Not Applicable	No human causal gene; not Mendelian
Pathogenic variants / ACMG classification / gnomAD allele frequency	Not Applicable	No heritable disease variants
Modifier genes, epigenetic changes, chromosomal abnormalities	Not Applicable	No genetic disease architecture
Inheritance pattern, penetrance, expressivity, anticipation, mosaicism, founder effects, consanguinity, carrier frequency	Not Applicable	Non-genetic
Genetic testing (WGS/WES/panels/single-gene/CMA/karyotype/FISH/mtDNA/repeat expansion)	Not Applicable	Diagnosis is microbiological + imaging
Genetic counseling / carrier & prenatal screening	Not Applicable	Non-heritable
Pharmacogenomics	Not Available	No PGx associations described for LS antibiotics in this context
Gene/cell/RNAi/CRISPR functional-genomics screens; human omics signatures	Not Available	No human transcriptomic/proteomic/metabolomic disease datasets identified

The scientifically meaningful "genetics" of this disease reside in the pathogen genome—the F. necrophorum leukotoxin operon (lktA) and the hemagglutinin-related protein gene, both confirmed by PCR and Southern hybridization in virulent isolates (PMID: 24590666).

Section-by-Section Digest

1. Disease information: MONDO:0015306; synonyms include necrobacillosis (human), postanginal sepsis, human necrobacillosis, "the forgotten disease." Information is derived from aggregated case series/systematic reviews and individual case reports (there is no large EHR-based cohort; the BATTLE registry, PMID: 33091703, is assembling disease-specific data).
2. Etiology: Infectious (predominantly F. necrophorum; expanding to streptococci and S. aureus). Risk factors: antecedent pharyngotonsillitis/peritonsillar abscess, young age, male sex, and inappropriate/restricted antibiotic use for sore throat. Smoking is an established risk factor for peritonsillar abscess (the main precursor). No genetic risk/protective factors; no established gene-environment interaction.
3. Phenotypes: Fever (92%), sore throat, neck pain/swelling, rigors, dyspnea, pleuritic chest pain, hemoptysis; laboratory: thrombocytopenia (~75%), elevated CRP, leukocytosis. Onset is acute in previously healthy young people; severity moderate-to-severe; course rapidly progressive then resolving with treatment.
4. Genetic/molecular: Not Applicable (see table above).
5. Environmental/infectious agents: Fusobacterium necrophorum subsp. necrophorum (biotype A, more virulent) and subsp. funduliforme; viridans streptococci; MRSA (Lemierre-like). No toxin/pollution etiology.
6. Mechanism: See causal chain above.
7. Anatomy: oropharynx/tonsils → internal jugular vein → lungs (dominant), with intracranial-sinus, pleural, joint, and orbital extension.
8. Temporal: acute/subacute onset days after pharyngitis; rapid progression; self-limited with treatment; no chronic/relapsing phase.
9. Inheritance/population: No inheritance. Incidence ~1–10/million/year (rising); median age ~15–20 years; male predominance; global distribution.
10. Diagnostics: contrast-enhanced neck/chest CT (IJV thrombosis + emboli) + anaerobic blood cultures; molecular (16S rDNA, targeted NGS/metagenomics); differential includes other deep-neck-space infections, viral pharyngitis, infectious mononucleosis, and non-septic venous thrombosis.
11. Prognosis: ~5% mortality (up to 80% historically); high acute morbidity; near-complete recovery with treatment; prognostic factors—diagnostic delay, septic shock, and extent of embolization.
12. Treatment: prolonged anaerobe-active antibiotics (beta-lactam/BLI or 3rd-gen cephalosporin + metronidazole, or carbapenem) + source control; anticoagulation controversial; IJV ligation/excision as salvage.
13. Prevention: secondary (early recognition + appropriate antibiotics); cost-effective throat-swab screening modeled but not implemented; no human vaccine.
14. Other species: major veterinary disease (bovine liver abscess, footrot; necrobacillosis in ruminants and wildlife); zoonotic transmission not a feature of human LS.
15. Model organisms: no dedicated rodent LS model; mechanistic work uses bovine PMN/leukocyte in-vitro systems and cattle field trials; a F. necrophorum bacterin vaccine is efficacious in cattle.

Evidence Base

PMID	Title (abbrev.)	Role in this report
42127655	Pediatric Lemierre's syndrome: A systematic review	Dominant pathogen (78.3%), CT utility (89.5%), fever (92%), complications 4.2%, anticoagulation 62.2%
41517763	Early diagnosis using targeted NGS + metagenomics	Definition; molecular diagnostics for culture-negative cases
31843654	Invasive F. necrophorum incl. LS: Swedish 8-year study	Rising incidence (2.9→5.0/M/yr); severity metrics; median age 20
42576194	Atypical LS in a child with nephrotic syndrome	Incidence estimate 3.6/million
40265142	A subtle presentation: Lemierre	Historical 80% / modern ~5% mortality; 7–15 day course
8711893	F. necrophorum virulence factors	Leukotoxin + endotoxin as principal virulence factors
12117974	Leukotoxin induces activation/apoptosis of bovine leukocytes	Mechanism of immune evasion (in-vitro/ruminant)
16701574	F. necrophorum infections in animals	Subspecies virulence; veterinary disease; "mechanism not well defined"
39840169	Early Radiographic Warning Signs	Confirmatory diagnostic standard; 4-day rapid progression
40224244	LS in an immunocompetent patient	First-line antibiotic regimen; contrast-enhanced CT
32909436	Anticoagulation strategies: systematic review	Anticoagulation controversy
42141231	Otogenic pediatric septic thrombophlebitis	Thrombosis distribution; 78% recanalization
20570017	"A forgotten disease"	Oropharyngeal source + pulmonary emboli; carbapenems
38363930	Lemierre-like syndrome after MRSA soft-tissue infection	Expanding etiologic spectrum; ~16% LLS mortality
42286749	Incomplete Lemierre's syndrome	Clinical variant definition
42517948	IJV excision in uncontrolled LS	Odontogenic/non-Fusobacterium cases; salvage surgery; DIC/ARDS
22886057	Cost-effectiveness of throat-swab screening	Secondary prevention economics ($8,795/QALY)
16363327	Vaccination against F. necrophorum in feedlot cattle	Bacterin efficacy (liver abscess OR 0.27; footrot OR 0.18)
24590666	Fusobacterium isolates from white-tailed deer	Leukotoxin operon confirmation; wildlife reservoir
12109395	Postanginal sepsis in South West Peninsula	Otogenic sources; antibiotic-use link to rising incidence
39257960	LS with extensive thrombosis	Surgical hierarchy; anticoagulation for extensive thrombosis
33091703	BATTLE registry rationale	Registry to address evidence gaps; broadened definition
28260599	Peritonsillar abscess microbiology & risk factors	Smoking as PTA risk factor; FN prevalence in the precursor lesion
42547547	Microbiological spectrum of peritonsillar abscesses	FN more common in adolescents; antibiotic susceptibility

Limitations and Knowledge Gaps

Mechanistic gap (human thrombogenesis): The step linking F. necrophorum virulence factors to actual IJV thrombus initiation in humans is inferred from in-vitro and ruminant data; direct human evidence of platelet aggregation/endothelial thrombus formation is lacking (Finding 12).
No human omics: No transcriptomic, proteomic, metabolomic, single-cell, or spatial datasets exist for human LS, limiting molecular annotation and biomarker discovery.
Evidence quality: The literature is dominated by case reports, retrospective series, and systematic reviews of heterogeneous cases; there are no randomized trials for the central management controversy (anticoagulation).
Definitional drift: "Lemierre-like" and "incomplete" variants broaden the disease boundary and complicate epidemiologic comparisons; incidence estimates vary (1–10/million/year).
Underdiagnosis/publication bias: As "the forgotten disease," LS may be under-recognized (biasing incidence downward) while severe/unusual cases are over-represented in the literature (biasing severity upward).
No dedicated small-animal model: Mechanistic study relies on cattle/bovine leukocyte systems, which may not fully recapitulate human neck-vein thrombophlebitis.

Proposed Follow-up Actions

Contribute to / mine the BATTLE registry (PMID: 33091703) for prospective, standardized data on presentation, management, and anticoagulation outcomes.
Design a pragmatic RCT of adjunctive anticoagulation in confirmed LS, stratified by extent of thrombosis and intracranial-sinus involvement, to resolve the central management controversy.
Human mechanistic studies: ex-vivo assays testing F. necrophorum leukotoxin, hemagglutinin, and outer-membrane factors against human platelets and jugular-vein endothelial cells to directly test the thrombus-initiation hypothesis (closing the Finding 12 gap).
Molecular diagnostics validation: prospective evaluation of targeted NGS/16S rDNA turnaround time and sensitivity versus anaerobic culture, to shorten diagnostic delay (the key modifiable prognostic factor).
Prospective evaluation of throat-swab screening in 15–24-year-olds for F. necrophorum pharyngitis to test the modeled cost-effectiveness (PMID: 22886057) as a secondary-prevention strategy.
Comparative-biology translation: leverage the efficacious bovine F. necrophorum bacterin (PMID: 16363327) and leukotoxin biology to explore antitoxin/antivirulence adjuncts, while recognizing the low human incidence limits vaccine feasibility.

Suggested Ontology Term Set (for knowledge-base ingestion)

Disease: MONDO:0015306 (Lemierre syndrome)
Pathogen / animal (NCBI Taxon): Fusobacterium necrophorum txid859; Bos taurus txid9913; Odocoileus virginianus txid9874
Anatomy (UBERON): internal jugular vein UBERON:0001584; oropharynx UBERON:0001729; palatine tonsil UBERON:0002373; lung UBERON:0002048; sigmoid sinus UBERON:0006459; cavernous sinus UBERON:0004024
Phenotypes (HP): Fever HP:0001945; Sepsis HP:0100806; Thrombocytopenia HP:0001873; Septic shock HP:0031273; Hemoptysis HP:0002105; Chest pain HP:0100749
Processes (GO): inflammatory response GO:0006954; apoptotic process GO:0006915; blood coagulation GO:0007596; toxin activity GO:0090729
Cells (CL): neutrophil CL:0000775; endothelial cell CL:0000115; platelet CL:0000233
Chemicals (CHEBI): lipopolysaccharide CHEBI:16412; metronidazole CHEBI:6077
Interventions (NCIT-type): antibacterial therapy; metronidazole; carbapenem; anticoagulant therapy; abscess drainage; internal jugular vein ligation

Evidence source types across this report: predominantly human clinical (case series, systematic reviews, registries); in-vitro/model-organism for virulence mechanism (bovine leukocytes, cattle field trials); computational/economic for prevention modeling. No germline-genetic or human-omics evidence exists for this disease.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.3.0rc1.

Outcome	Count
References checked	24
Resolved	24
Unresolved (possible confabulation)	0
Unverifiable	0
References weighed for topical relevance	24
On topic	20
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	24
Resolved	24
Unresolved (possible confabulation)	0
Obsolete	0
Unverifiable	0
Terms whose name was checked	16
Terms named correctly	12
Terms named as a different term	2
Terms whose name is worth a second look	2

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:

UBERON:0001584 (3 mentions) - the report calls it "internal jugular vein", "Internal jugular vein"; UBERON calls it left subclavian artery
CHEBI:6077 (2 mentions) - the report calls it "metronidazole"; CHEBI calls it Ivalin

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:

HP:0031273 (2 mentions) - the report calls it "Septic shock"; HP calls it Shock
HP:0002098 (1 mention) - the report calls it "Respiratory distress/dyspnea"; HP calls it Respiratory distress

Terms named inconsistently

The report gives these identifiers more than one name of its own:

UBERON:0001584 - called "internal jugular vein", "Internal jugular vein"

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References & Deep Research

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Lemierre Syndrome: A Comprehensive Disease Characteristics Report

Summary

Key Findings

Finding 1 — Definition and dominant pathogen

Finding 2 — Epidemiology: rare, rising, young, male-predominant

Finding 3 — Severe systemic illness; ~5% modern mortality

Finding 4 — Leukotoxin is the major virulence factor

Finding 5 — Diagnosis: contrast-enhanced CT + anaerobic blood cultures + molecular methods

Finding 6 — Treatment: prolonged anaerobe-active antibiotics + source control; anticoagulation controversial

Finding 7 — Anatomy and phenotypes

Finding 8 — Not genetic; expanding etiologic spectrum ("Lemierre-like syndrome")

Finding 9 — Natural animal disease and models (necrobacillosis)

Finding 10 — Prevention is secondary; no human vaccine

Finding 11 — Temporal course: acute onset, rapid progression, self-limited with treatment

Finding 12 — Evidence gap: human thrombus-initiation step is inferred

Mechanistic Model / Interpretation

Ordered causal chain (initiating lesion → clinical manifestation)

Not Applicable / Not Available Sections (explicit)

Section-by-Section Digest

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Actions

Suggested Ontology Term Set (for knowledge-base ingestion)

Artifacts

Reference Validation

Term Validation

Terms the report names something else

Terms whose name is worth a second look

Terms named inconsistently