Southern Tick-Associated Rash Illness

Infectious MONDO:0025294 Tick-Borne Disease Dermatologic Disease

Southern tick-associated rash illness (STARI) is an acute lone-star-tick-associated erythema-migrans-like syndrome reported mainly in the southeastern, south-central, and broader eastern United States. Its presentation overlaps early Lyme disease, but microbiologic studies have not confirmed Borrelia burgdorferi, Borrelia lonestari, or another defined bacterial pathogen as the cause, and no validated laboratory diagnostic test exists. In the classic Missouri cohorts, patients were less symptomatic, more often had smaller circular lesions with central clearing, and recovered more rapidly after empiric antibiotic treatment than New York patients with early Lyme disease.

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2
Mappings
2
Definitions
3
Pathophys.
6
Phenotypes
1
Differentials
1
Deep Research
🔗

Mappings

MONDO
MONDO:0025294 tick-borne infectious disease
skos:closeMatch MONDO
Closest available MONDO parent term while MONDO new term request #9873 for southern tick-associated rash illness remains open.
NCIT
NCIT:C128427 Southern Tick-Associated Rash Illness
skos:exactMatch NCIT
Direct NCIT disease concept for STARI / Masters disease.
NCIT
NCIT:C128427 Southern Tick-Associated Rash Illness
skos:exactMatch NCIT
Direct NCIT disease concept for STARI / Masters disease.
📘

Definitions

2
Clinical syndrome definition for STARI
STARI is an illness associated with an erythema-migrans-like skin lesion after lone star tick exposure in the southern United States and is not caused by Borrelia burgdorferi.
CASE_DEFINITION Disease-level clinical framing of the STARI syndrome
Show evidence (1 reference)
PMID:16142659 SUPPORT Human Clinical
"An illness associated with an EM-like skin lesion, but which is not caused by B. burgdorferi, occurs in many southern states in the United States"
This provides a compact disease-level definition anchoring STARI as a southern US erythema-migrans-like syndrome distinct from Lyme disease.
Diagnostic limitation and Lyme distinction
STARI remains a clinical diagnosis because no laboratory assay can confirm it or reliably distinguish it from early Lyme disease.
DIAGNOSTIC_CRITERIA Practical diagnostic framing in regions where STARI and Lyme overlap
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"Clinically, the skin lesions of STARI and early Lyme disease are indistinguishable, and no laboratory tool or method exists for the diagnosis of STARI or differentiation of STARI from Lyme disease."
Supports the current clinical-reasoning framework: STARI is recognized as a syndrome, but there is no validated confirmatory laboratory test.
⚙

Pathophysiology

3
Lone star tick bite-associated syndrome of unknown etiology
Repeated microbiologic studies have failed to confirm a consistent bacterial cause for STARI. Both early Missouri skin-biopsy work and contemporary 16S sequencing continue to support an unresolved etiology.
Show evidence (2 references)
PMID:15668867 SUPPORT Human Clinical
"Neither B. lonestari nor B. burgdorferi is likely to be the cause of EM-like skin lesions in patients from the Cape Girardeau area of Missouri. The etiology of this condition remains unknown."
Foundational microbiologic study ruling out both B. burgdorferi and B. lonestari in classic Missouri STARI cases.
PMID:40517644 SUPPORT Human Clinical
"Using 16S sequencing, no known bacterial pathogen was detected. Although an etiologic agent remains unknown, these results do provide updated information on rash color, shape, duration, and treatment outcomes."
Contemporary cohort data continue to support that no known bacterial pathogen explains STARI.
Non-Lyme biologic context of Amblyomma americanum bites
Lone star ticks are not competent vectors for Borrelia burgdorferi, and their saliva directly reduces Borrelia viability. This supports modeling STARI as a lone-star-tick-associated syndrome that is biologically distinct from classic Lyme transmission.
Show evidence (2 references)
PMID:15752182 SUPPORT In Vitro
"A possible mechanism that could prevent acquisition of B. burgdorferi spirochetes from infected hosts is the toxic effect of A. americanum saliva on B. burgdorferi."
Provides a mechanistic reason that bites from A. americanum do not simply replicate Ixodes-mediated Lyme transmission biology.
PMID:15752182 SUPPORT In Vitro
"After 48 h, fewer than 13% of saliva-exposed B. burgdorferi were alive."
Directly demonstrates borreliacidal activity of lone star tick saliva against the Lyme spirochete.
Distinct host metabolic response from early Lyme disease
Patient-serum metabolomics identifies a biochemical state in STARI that differs substantially from early Lyme disease, including altered endocannabinoid-like lipid mediator pathways.
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"These findings revealed metabolic dissimilarity between early Lyme disease and STARI, and provide a powerful and new approach to inform patient management by objectively distinguishing early Lyme disease from an illness with nearly identical symptoms."
Supports STARI as a distinct host-response state rather than just a geographic variant of early Lyme disease.
●

Phenotypes

6
Cardiovascular 1
Erythema migrans-like rash Erythema migrans (HP:0031180)
Show evidence (1 reference)
PMID:16142659 SUPPORT Human Clinical
"EM-like lesions in Missouri cases were smaller in size than those in New York cases (8.3+/-2.2 cm and 16.4+/-11.5 cm, respectively; P<.001), more circular in shape (P=.004), and more likely to have central clearing (76.2% and 21.6%, respectively; P<.001)."
Supports the hallmark rash morphology of STARI in the classic Missouri cohort.
Metabolism 1
Fever Fever (HP:0001945)
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"STARI, is associated with a bite from the lone star tick (Amblyomma americanum), and in addition to the development of an EM-like skin lesion, individuals with STARI can present with mild systemic symptoms (including muscle and joint pains, fatigue, fever, chills, and headache) that are similar..."
The cohort summary explicitly includes fever among mild systemic symptoms reported in STARI.
Nervous System 1
Headache Headache (HP:0002315)
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"STARI, is associated with a bite from the lone star tick (Amblyomma americanum), and in addition to the development of an EM-like skin lesion, individuals with STARI can present with mild systemic symptoms (including muscle and joint pains, fatigue, fever, chills, and headache) that are similar..."
The cohort summary explicitly includes headache among common mild systemic symptoms.
Constitutional 3
Fatigue Fatigue (HP:0012378)
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"STARI, is associated with a bite from the lone star tick (Amblyomma americanum), and in addition to the development of an EM-like skin lesion, individuals with STARI can present with mild systemic symptoms (including muscle and joint pains, fatigue, fever, chills, and headache) that are similar..."
The metabolomics cohort summary explicitly includes fatigue among common mild systemic symptoms.
Myalgia Myalgia (HP:0003326)
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"STARI, is associated with a bite from the lone star tick (Amblyomma americanum), and in addition to the development of an EM-like skin lesion, individuals with STARI can present with mild systemic symptoms (including muscle and joint pains, fatigue, fever, chills, and headache) that are similar..."
The cohort summary explicitly includes muscle pains among common mild systemic symptoms.
Arthralgia Arthralgia (HP:0002829)
Show evidence (1 reference)
PMID:28814545 SUPPORT Human Clinical
"STARI, is associated with a bite from the lone star tick (Amblyomma americanum), and in addition to the development of an EM-like skin lesion, individuals with STARI can present with mild systemic symptoms (including muscle and joint pains, fatigue, fever, chills, and headache) that are similar..."
The cohort summary explicitly includes joint pains among common mild systemic symptoms.
🔀

Differential Diagnoses

1

Conditions with similar clinical presentations that must be differentiated from Southern Tick-Associated Rash Illness:

Lyme disease MONDO:0019632
Overlapping Features Ixodes-transmitted Borrelia burgdorferi infection that also presents with erythema migrans but has a defined bacterial etiology, available laboratory testing, and greater potential for disseminated multisystem disease.
Distinguishing Features
  • Lyme disease has a defined bacterial etiology, whereas STARI remains of unknown cause and has no validated laboratory diagnostic test.
  • Missouri STARI patients were less symptomatic, more often had single smaller circular lesions with central clearing, and recovered more rapidly after antibiotic treatment than New York early Lyme disease patients.
Show evidence (2 references)
PMID:28814545 SUPPORT Human Clinical
"This, however, can be confused with other illnesses including southern tick-associated rash illness (STARI), an illness that lacks a defined etiological agent or laboratory diagnostic test, and is coprevalent with Lyme disease in portions of the eastern United States."
This directly frames STARI as a Lyme mimic while emphasizing the lack of a defined etiologic agent or test.
PMID:16142659 SUPPORT Human Clinical
"After antibiotic treatment, Missouri case patients recovered more rapidly than did New York case patients (P=.037)."
Supports the more favorable short-term course of classic Missouri STARI compared with comparator New York early Lyme disease cases.
{ }

Source YAML

click to show 
name: Southern Tick-Associated Rash Illness
creation_date: "2026-04-16T19:00:00Z"
updated_date: "2026-04-16T19:00:00Z"
category: Infectious
description: >-
  Southern tick-associated rash illness (STARI) is an acute lone-star-tick-associated
  erythema-migrans-like syndrome reported mainly in the southeastern, south-central,
  and broader eastern United States. Its presentation overlaps early Lyme disease,
  but microbiologic studies have not confirmed Borrelia burgdorferi, Borrelia
  lonestari, or another defined bacterial pathogen as the cause, and no validated
  laboratory diagnostic test exists. In the classic Missouri cohorts, patients were
  less symptomatic, more often had smaller circular lesions with central clearing,
  and recovered more rapidly after empiric antibiotic treatment than New York
  patients with early Lyme disease.
disease_term:
  preferred_term: southern tick-associated rash illness
  term:
    id: MONDO:0025294
    label: tick-borne infectious disease
synonyms:
  - STARI
  - Masters disease
mappings:
  mondo_mappings:
    - term:
        id: MONDO:0025294
        label: tick-borne infectious disease
      mapping_predicate: skos:closeMatch
      mapping_source: MONDO
      mapping_justification: >-
        Closest available MONDO parent term while MONDO new term request #9873
        for southern tick-associated rash illness remains open.
      tracked_issues:
        - url: https://github.com/monarch-initiative/mondo/issues/9873
          title: Request for new term Southern tick-associated rash illness
          tracked_issue_role: ontology_term_request
          tracked_issue_status: OPEN
          notes: >-
            Upstream MONDO request for an exact STARI term with exact synonyms
            STARI and Masters disease.
  ncit_mappings:
    - term:
        id: NCIT:C128427
        label: Southern Tick-Associated Rash Illness
      mapping_predicate: skos:exactMatch
      mapping_source: NCIT
      mapping_justification: Direct NCIT disease concept for STARI / Masters disease.
parents:
  - Tick-Borne Disease
  - Dermatologic Disease
definitions:
  - name: Clinical syndrome definition for STARI
    definition_type: CASE_DEFINITION
    description: >-
      STARI is an illness associated with an erythema-migrans-like skin lesion
      after lone star tick exposure in the southern United States and is not
      caused by Borrelia burgdorferi.
    scope: Disease-level clinical framing of the STARI syndrome
    evidence:
      - reference: PMID:16142659
        reference_title: >-
          Prospective clinical evaluation of patients from Missouri and New York
          with erythema migrans-like skin lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "An illness associated with an EM-like skin lesion, but which is not caused by B. burgdorferi, occurs in many southern states in the United States"
        explanation: >-
          This provides a compact disease-level definition anchoring STARI as a
          southern US erythema-migrans-like syndrome distinct from Lyme disease.
  - name: Diagnostic limitation and Lyme distinction
    definition_type: DIAGNOSTIC_CRITERIA
    description: >-
      STARI remains a clinical diagnosis because no laboratory assay can confirm
      it or reliably distinguish it from early Lyme disease.
    scope: Practical diagnostic framing in regions where STARI and Lyme overlap
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Clinically, the skin lesions of STARI and early Lyme disease are
          indistinguishable, and no laboratory tool or method exists for the
          diagnosis of STARI or differentiation of STARI from Lyme disease.
        explanation: >-
          Supports the current clinical-reasoning framework: STARI is recognized
          as a syndrome, but there is no validated confirmatory laboratory test.
transmission:
  - name: Lone star tick bite-associated transmission
    description: >-
      STARI is associated with bites of the lone star tick, Amblyomma
      americanum.
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI, is associated with a bite from the lone star tick (Amblyomma
          americanum), and in addition to the development of an EM-like skin
          lesion, individuals with STARI can present with mild systemic
          symptoms (including muscle and joint pains, fatigue, fever, chills,
          and headache) that are similar to those occurring in patients with
          Lyme disease.
        explanation: >-
          This directly ties STARI to lone star tick bites and also summarizes
          the typical rash-plus-mild-systemic-symptom presentation.
epidemiology:
  - name: Geographic overlap with lone star tick range
    description: >-
      STARI occurs where lone star ticks are established and overlaps Lyme
      disease in parts of the eastern United States, creating diagnostic
      ambiguity.
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI cases occur over the geographic region where the lone star tick
          is present. This includes a region that currently expands from
          central Texas and Oklahoma upward into the Midwestern states and
          eastward, including the southern states and along the Atlantic coast
          into Maine.
        explanation: >-
          Supports the broad eastern and southern US range of STARI tied to the
          distribution of A. americanum.
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Importantly, a strict geographic segregation of Lyme disease and
          STARI does not exist, as there are regions where STARI and Lyme
          disease are co-prevalent.
        explanation: >-
          Confirms the clinically important geographic overlap between STARI and
          Lyme disease.
  - name: Historical southeastern and east-coast case distribution
    description: >-
      Historical reports clustered in southeastern Missouri and several
      southeastern states, with subsequent extension along the East Coast as
      the lone star tick range expanded.
    evidence:
      - reference: PMID:30129909
        reference_title: >-
          Report of Non-Lyme, Erythema Migrans Rashes from New Jersey with a
          Review of Possible Role of Tick Salivary Toxins.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Cases of Lyme-like EM rashes referred to as STARI (Southern Tick-Associated Rash Illness) following bites of the lone star tick, Amblyomma americanum, in the United States have been reported predominantly in Southeastern Missouri and a few in South Carolina, North Carolina, Georgia, and one case each in Mississippi and Long Island, New York."
        explanation: >-
          Summarizes the earlier southeastern concentration of reported STARI cases.
      - reference: PMID:30129909
        reference_title: >-
          Report of Non-Lyme, Erythema Migrans Rashes from New Jersey with a
          Review of Possible Role of Tick Salivary Toxins.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Distribution of A. americanum, whose bites are associated with STARI, now extends along the East Coast of the United States, including New Jersey, up to the Canadian border."
        explanation: >-
          Supports east-coast expansion of the associated vector range.
progression:
  - phase: Early localized rash-predominant illness
    notes: >-
      Compared with New York early Lyme disease cases, Missouri STARI cases
      were more often single-lesion, less symptomatic, and morphologically more
      circular with central clearing.
    evidence:
      - reference: PMID:16142659
        reference_title: >-
          Prospective clinical evaluation of patients from Missouri and New York
          with erythema migrans-like skin lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Missouri case patients were less likely to be symptomatic than were
          New York case patients (19.0% and 76.2%, respectively; P<.001), and
          Missouri case patients were less likely to have multiple skin lesions
          (4.8% and 26.7%, respectively; P=.042).
        explanation: >-
          Supports STARI as a largely localized and less systemically
          symptomatic syndrome than comparator New York early Lyme disease.
      - reference: PMID:16142659
        reference_title: >-
          Prospective clinical evaluation of patients from Missouri and New York
          with erythema migrans-like skin lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          EM-like lesions in Missouri cases were smaller in size than those in
          New York cases (8.3+/-2.2 cm and 16.4+/-11.5 cm, respectively;
          P<.001), more circular in shape (P=.004), and more likely to have
          central clearing (76.2% and 21.6%, respectively; P<.001).
        explanation: >-
          Documents the characteristic STARI lesion morphology in the Missouri
          cohort.
  - phase: Recovery after empiric treatment
    notes: >-
      In the classic Missouri/New York comparison, Missouri STARI patients
      improved more rapidly after empiric antibiotic therapy than New York
      patients with early Lyme disease.
    evidence:
      - reference: PMID:16142659
        reference_title: >-
          Prospective clinical evaluation of patients from Missouri and New York
          with erythema migrans-like skin lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          After antibiotic treatment, Missouri case patients recovered more
          rapidly than did New York case patients (P=.037).
        explanation: >-
          Supports the commonly cited clinical impression that STARI has a more
          favorable short-term course than early Lyme disease.
pathophysiology:
  - name: Lone star tick bite-associated syndrome of unknown etiology
    description: >-
      Repeated microbiologic studies have failed to confirm a consistent
      bacterial cause for STARI. Both early Missouri skin-biopsy work and
      contemporary 16S sequencing continue to support an unresolved etiology.
    evidence:
      - reference: PMID:15668867
        reference_title: >-
          Microbiologic evaluation of patients from Missouri with erythema
          migrans.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Neither B. lonestari nor B. burgdorferi is likely to be the cause of
          EM-like skin lesions in patients from the Cape Girardeau area of
          Missouri. The etiology of this condition remains unknown.
        explanation: >-
          Foundational microbiologic study ruling out both B. burgdorferi and
          B. lonestari in classic Missouri STARI cases.
      - reference: PMID:40517644
        reference_title: >-
          Epidemiologic and clinical characteristics and outcomes of patients
          diagnosed with Southern Tick Associated Rash Illness (STARI) -
          2018-2019.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Using 16S sequencing, no known bacterial pathogen was detected.
          Although an etiologic agent remains unknown, these results do provide
          updated information on rash color, shape, duration, and treatment
          outcomes.
        explanation: >-
          Contemporary cohort data continue to support that no known bacterial
          pathogen explains STARI.
  - name: Non-Lyme biologic context of Amblyomma americanum bites
    description: >-
      Lone star ticks are not competent vectors for Borrelia burgdorferi, and
      their saliva directly reduces Borrelia viability. This supports modeling
      STARI as a lone-star-tick-associated syndrome that is biologically
      distinct from classic Lyme transmission.
    evidence:
      - reference: PMID:15752182
        reference_title: >-
          Borreliacidal activity of saliva of the tick Amblyomma americanum.
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: >-
          A possible mechanism that could prevent acquisition of B. burgdorferi
          spirochetes from infected hosts is the toxic effect of A.
          americanum saliva on B. burgdorferi.
        explanation: >-
          Provides a mechanistic reason that bites from A. americanum do not
          simply replicate Ixodes-mediated Lyme transmission biology.
      - reference: PMID:15752182
        reference_title: >-
          Borreliacidal activity of saliva of the tick Amblyomma americanum.
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: >-
          After 48 h, fewer than 13% of saliva-exposed B. burgdorferi were
          alive.
        explanation: >-
          Directly demonstrates borreliacidal activity of lone star tick saliva
          against the Lyme spirochete.
  - name: Distinct host metabolic response from early Lyme disease
    description: >-
      Patient-serum metabolomics identifies a biochemical state in STARI that
      differs substantially from early Lyme disease, including altered
      endocannabinoid-like lipid mediator pathways.
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          These findings revealed metabolic dissimilarity between early Lyme
          disease and STARI, and provide a powerful and new approach to inform
          patient management by objectively distinguishing early Lyme disease
          from an illness with nearly identical symptoms.
        explanation: >-
          Supports STARI as a distinct host-response state rather than just a
          geographic variant of early Lyme disease.
phenotypes:
  - name: Erythema migrans-like rash
    category: Dermatologic
    description: >-
      Expanding annular bite-site lesion that is typically smaller, more
      circular, and more likely to show central clearing than comparator New
      York early Lyme lesions.
    phenotype_term:
      preferred_term: Erythema migrans-like rash
      term:
        id: HP:0031180
        label: Erythema migrans
    evidence:
      - reference: PMID:16142659
        reference_title: >-
          Prospective clinical evaluation of patients from Missouri and New York
          with erythema migrans-like skin lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          EM-like lesions in Missouri cases were smaller in size than those in
          New York cases (8.3+/-2.2 cm and 16.4+/-11.5 cm, respectively;
          P<.001), more circular in shape (P=.004), and more likely to have
          central clearing (76.2% and 21.6%, respectively; P<.001).
        explanation: >-
          Supports the hallmark rash morphology of STARI in the classic
          Missouri cohort.
  - name: Fatigue
    category: Constitutional
    description: Mild fatigue can accompany the rash.
    phenotype_term:
      preferred_term: Fatigue
      term:
        id: HP:0012378
        label: Fatigue
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI, is associated with a bite from the lone star tick (Amblyomma
          americanum), and in addition to the development of an EM-like skin
          lesion, individuals with STARI can present with mild systemic
          symptoms (including muscle and joint pains, fatigue, fever, chills,
          and headache) that are similar to those occurring in patients with
          Lyme disease.
        explanation: The metabolomics cohort summary explicitly includes fatigue among common mild systemic symptoms.
  - name: Fever
    category: Constitutional
    description: Mild fever may accompany the rash.
    phenotype_term:
      preferred_term: Fever
      term:
        id: HP:0001945
        label: Fever
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI, is associated with a bite from the lone star tick (Amblyomma
          americanum), and in addition to the development of an EM-like skin
          lesion, individuals with STARI can present with mild systemic
          symptoms (including muscle and joint pains, fatigue, fever, chills,
          and headache) that are similar to those occurring in patients with
          Lyme disease.
        explanation: The cohort summary explicitly includes fever among mild systemic symptoms reported in STARI.
  - name: Headache
    category: Neurological
    description: Mild headache can accompany the rash illness.
    phenotype_term:
      preferred_term: Headache
      term:
        id: HP:0002315
        label: Headache
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI, is associated with a bite from the lone star tick (Amblyomma
          americanum), and in addition to the development of an EM-like skin
          lesion, individuals with STARI can present with mild systemic
          symptoms (including muscle and joint pains, fatigue, fever, chills,
          and headache) that are similar to those occurring in patients with
          Lyme disease.
        explanation: The cohort summary explicitly includes headache among common mild systemic symptoms.
  - name: Myalgia
    category: Musculoskeletal
    description: Mild muscle pain may occur with the rash illness.
    phenotype_term:
      preferred_term: Myalgia
      term:
        id: HP:0003326
        label: Myalgia
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI, is associated with a bite from the lone star tick (Amblyomma
          americanum), and in addition to the development of an EM-like skin
          lesion, individuals with STARI can present with mild systemic
          symptoms (including muscle and joint pains, fatigue, fever, chills,
          and headache) that are similar to those occurring in patients with
          Lyme disease.
        explanation: The cohort summary explicitly includes muscle pains among common mild systemic symptoms.
  - name: Arthralgia
    category: Musculoskeletal
    description: Mild joint pain may occur with the rash illness.
    phenotype_term:
      preferred_term: Arthralgia
      term:
        id: HP:0002829
        label: Arthralgia
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          STARI, is associated with a bite from the lone star tick (Amblyomma
          americanum), and in addition to the development of an EM-like skin
          lesion, individuals with STARI can present with mild systemic
          symptoms (including muscle and joint pains, fatigue, fever, chills,
          and headache) that are similar to those occurring in patients with
          Lyme disease.
        explanation: The cohort summary explicitly includes joint pains among common mild systemic symptoms.
differential_diagnoses:
  - name: Lyme disease
    disease_term:
      preferred_term: Lyme disease
      term:
        id: MONDO:0019632
        label: Lyme disease
    description: >-
      Ixodes-transmitted Borrelia burgdorferi infection that also presents with
      erythema migrans but has a defined bacterial etiology, available
      laboratory testing, and greater potential for disseminated multisystem
      disease.
    distinguishing_features:
      - Lyme disease has a defined bacterial etiology, whereas STARI remains of unknown cause and has no validated laboratory diagnostic test.
      - Missouri STARI patients were less symptomatic, more often had single smaller circular lesions with central clearing, and recovered more rapidly after antibiotic treatment than New York early Lyme disease patients.
    evidence:
      - reference: PMID:28814545
        reference_title: >-
          Metabolic differentiation of early Lyme disease from southern
          tick-associated rash illness (STARI).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          This, however, can be confused with other illnesses including
          southern tick-associated rash illness (STARI), an illness that lacks
          a defined etiological agent or laboratory diagnostic test, and is
          coprevalent with Lyme disease in portions of the eastern United
          States.
        explanation: >-
          This directly frames STARI as a Lyme mimic while emphasizing the lack
          of a defined etiologic agent or test.
      - reference: PMID:16142659
        reference_title: >-
          Prospective clinical evaluation of patients from Missouri and New York
          with erythema migrans-like skin lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          After antibiotic treatment, Missouri case patients recovered more
          rapidly than did New York case patients (P=.037).
        explanation: >-
          Supports the more favorable short-term course of classic Missouri
          STARI compared with comparator New York early Lyme disease cases.
notes: >-
  This entry intentionally does not assert an infectious_agent because repeated
  studies have not established B. burgdorferi, B. lonestari, or another known
  bacterial pathogen as the cause of STARI. NCIT provides an exact disease
  concept (NCIT:C128427), whereas MONDO currently requires close matching to
  MONDO:0025294 pending new term request #9873. Tick-saliva-mediated mechanisms
  have been proposed as one explanation for why lone star tick bites can cause
  EM-like illness without classic Lyme transmission, but this remains a
  hypothesis rather than a confirmed disease mechanism.
📚

References & Deep Research

Deep Research

1
Manual Pubmed Review ▸
Southern Tick-Associated Rash Illness (STARI): Manual Curation Summary
n/a 7 citations 2026-04-16T19:45:00Z

Southern Tick-Associated Rash Illness (STARI): Manual Curation Summary

Disease framing and lumping/splitting

STARI should be curated as its own lone-star-tick-associated erythema-migrans-like syndrome, not as a subtype of Lyme disease. The strongest comparative clinical study states that an EM-like illness not caused by Borrelia burgdorferi occurs in many southern US states and is known as STARI / Masters disease (PMID:16142659). The 2022 Lyme review likewise treats STARI as one of the principal mimics of early Lyme disease rather than as a geographic Lyme variant (PMID:36116832).

The local MONDO anchor is necessarily imperfect. MONDO issue #9873 requests an exact term for “Southern tick-associated rash illness” with exact synonyms STARI and Masters disease, under the parent MONDO:0025294 tick-borne infectious disease. Until that request is resolved, local curation should use a close match to MONDO:0025294 plus the tracked issue, while NCIT already provides an exact concept (NCIT:C128427 Southern Tick-Associated Rash Illness).

Microbiology and etiology

The core curation point is that the etiologic agent remains unknown.

The foundational 2005 Missouri microbiology study found that neither B. lonestari nor B. burgdorferi was likely to be the cause of the Missouri EM-like lesions; the abstract explicitly concludes that the etiology remains unknown (PMID:15668867). This remains current rather than historical: a 2025 CDC-associated series of 58 STARI patients reported that 16S sequencing detected no known bacterial pathogen and again stated that the etiologic agent remains unknown (PMID:40517644).

This means the dismech entry should not assert an infectious_agent despite the clinical syndrome’s strong tick association and its current placement under a broad MONDO infectious parent.

Mechanism-relevant observations

There is still no confirmed linear disease mechanism. The strongest curation-ready mechanistic observations are:

  1. Unknown cause despite microbiologic workup Multiple cohorts have failed to identify a causative bacterium (PMID:15668867, PMID:40517644).

  2. A. americanum bites are biologically distinct from Lyme transmission Lone star tick saliva is borreliacidal in vitro, with fewer than 13% of exposed B. burgdorferi surviving after 48 hours in one experiment (PMID:15752182). This does not explain STARI, but it strongly supports that A. americanum bites do not simply reproduce classic Lyme transmission biology.

  3. STARI is biochemically distinct from early Lyme disease Human-serum metabolomics differentiated early Lyme disease from STARI with high accuracy and concluded that the two illnesses are metabolically dissimilar (PMID:28814545). This is strong evidence that STARI is a distinct host-response state even though the upstream trigger remains unresolved.

  4. Tick salivary toxins remain a hypothesis, not an established mechanism A 2018 review/case report series proposed that tick salivary toxins may contribute to EM-like rashes and laboratory abnormalities, but this should be captured only as a note-level hypothesis rather than a core pathophysiology claim (PMID:30129909).

Geography and differential with Lyme disease

The geography follows the range of the lone star tick rather than the classic Lyme vectors. The metabolomics study states that STARI occurs where Amblyomma americanum is present, extending from central Texas/Oklahoma through the Midwest and eastward across the southern states and Atlantic coast into Maine, with overlap zones where Lyme disease and STARI are co-prevalent (PMID:28814545).

The 2018 New Jersey review is also useful for curation because it captures the historically reported concentration in southeastern Missouri and several southeastern states while noting east-coast expansion of the vector range (PMID:30129909).

The 2022 review provides the clearest high-level differential diagnosis framing: STARI is a condition causing a similar lesion after a tick bite but of unknown cause (PMID:36116832). This paper is also excellent support for the statement that no laboratory tool exists to diagnose STARI or differentiate it from Lyme disease.

Clinical phenotype and course

The 2005 prospective Missouri versus New York comparison remains the key paper for disease-level phenotype and prognosis claims (PMID:16142659):

  • Missouri patients were less likely to be symptomatic than New York early Lyme patients.
  • Missouri lesions were smaller, more circular, and more likely to have central clearing.
  • Missouri patients were less likely to have multiple lesions.
  • After antibiotic treatment, Missouri patients recovered more rapidly than New York patients.

The metabolomics paper complements this by summarizing the usual mild systemic symptoms: fatigue, fever, headache, and muscle/joint pains in addition to the EM-like lesion (PMID:28814545).

These findings justify modeling STARI as a primarily localized rash-predominant illness with mild constitutional symptoms and a more favorable short-term course than comparator early Lyme disease, while avoiding strong claims about long-term complications because the available abstract-level evidence is limited.

Practical curation takeaways

  • Use a close MONDO match to MONDO:0025294 with tracked issue #9873.
  • Add an exact NCIT mapping to NCIT:C128427.
  • Do not assert a specific infectious agent.
  • Keep the mechanistic story conservative:
  • unknown etiology
  • non-Lyme biologic context of lone star tick bites
  • metabolically distinct from early Lyme disease
  • Use Lyme disease as the primary differential diagnosis.
  • Prefer the 2005 Missouri/New York paper and the 2025 CDC-associated outcomes paper for concise disease-level evidence.

References

  • MONDO NTR issue: https://github.com/monarch-initiative/mondo/issues/9873
  • PMID:15668867
  • PMID:15752182
  • PMID:16142659
  • PMID:28814545
  • PMID:30129909
  • PMID:36116832
  • PMID:40517644