II. Pathophysiology

  1. Aerobic, intracellular, Gram Negative Rod
    1. Virulent organism
    2. More severe disease than other Atypical Pneumonia
  2. Transmission
    1. Optimal conditions for growth
      1. Temperature: 89 to 113 F water
      2. Stagnant water
    2. Waterborne Illness
      1. Freshwater or moist soil near ponds
      2. Air conditioning
      3. Condensers
      4. Cooling towers
      5. Respiratory therapy equipment
      6. Showers or water faucets
      7. Whirlpools
      8. Aeorsolized mist (hot tubs, decorative fountains)
  3. Incubation
    1. Two to ten days

III. Risk Factors

  1. Tobacco Smoking
  2. Chronic Renal Failure
  3. Malignancy
  4. Immunosuppression
  5. Diabetes Mellitus
  6. Chronic Liver Disease
  7. Exposure to recent plumbing work
  8. Overnight stay outside the home

IV. Presentations

  1. Legionellosis (severe illness, Pneumonia)
    1. Legionella pneumonia
  2. Pontiac Fever (mild, Influenza-like illness)

V. Symptoms

  1. Prodrome for 12-48 hours
    1. Malaise
    2. Myalgia
    3. Headache
  2. Symptoms for 2-3 days
    1. Fever to 40.5 C persists for 8-10 days
    2. Gastrointestinal symptoms in 20-40% of cases
      1. Nausea or Vomiting
      2. Diarrhea
  3. Later Symptoms: Cough
    1. Minimal to no Sputum production
    2. Slightly blood tinged Sputum

VI. Signs

  1. Severe respiratory distress
  2. Confusion
  3. Disorientation

VII. Complications

VIII. Radiology: Chest XRay

  1. Small Pleural Effusions
  2. Unilateral parenchymal infiltrates
    1. Round, fluffy opacities
    2. Spread contiguously to other lobes
    3. Progresses to dense consolidation
    4. Progresses to bilateral infiltrates

IX. Labs

  1. Complete Blood Count
    1. Leukocytosis
    2. Leukopenia
  2. Erythrocyte Sedimentation Rate
    1. Elevated markedly
  3. Liver Function Tests increased
  4. Sputum Exam
    1. Fluorescent Antibody studies of Sputum
    2. Legionella can not be seen on Gram Stain

X. Diagnosis

  1. Legionella urine Antigen testing
    1. High sensitivity and Specificity for serogroup 1
      1. Serogroup 1 (LP1) causes most U.S. cases (80%)
    2. Sputum Culture required to identify other serogroups
      1. Urine Antigen and Sputum Culture all cases
    3. References
      1. Benin (2002) Clin Infect Dis 35:1039-46 [PubMed]
  2. Concurrent Sputum and Blood Culture in all suspected cases (before antibiotics)
    1. Sputum Culture on special medium
  3. Legionella Serologies
    1. Legionella fourfold titer rise to >= 1:128 or
    2. Legionella titer >= 1:256

XI. Management (Antibiotic course for 21 days)

XII. Course

  1. Response to antibiotics may not be seen for 4-5 days
  2. Up to 10-15% mortality in some studies

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Related Studies

Ontology: Legionellosis (C0023240)

Definition (MSH) Infections with bacteria of the genus LEGIONELLA.
Definition (CSP) gram negative bacterial infection by any species of Legionella including Legionnaire's disease, which is characterized by high fever, malaise, muscle aches, respiratory disorders and headache.
Concepts Disease or Syndrome (T047)
MSH D007876
SnomedCT 26726000
LNC LA10483-8
English Legionelloses, Legionella infections, Legionellosis [Disease/Finding], legionella infection, legionellosis, Legionella infection NOS, Legionella infection, Legionella infection (disorder), Legionella infection, NOS, Legionellosis, NOS, Legionellosis
Italian Infezione da legionella, Infezioni da legionella, Infezione da Legionella NAS, Legionellosi
Dutch Legionella-infectie NAO, Legionella-infecties, Legionella-infectie, Legionellose
French Infection à Légionella SAI, Infections à Legionella, Infection à Légionella, Légionellose, Infection à Legionella, Infection à légionelles
German Legionella NNB, Legionella-Infektionen, Legionelleninfektion, Legionellose
Portuguese Infecção por legionela NE, Infecção por legionela, Infecções a legionela, Legionelose
Spanish Legionella NEOM, infección por Legionella, legionelosis (trastorno), legionelosis, Legionella, Infecciones por legionella, Legionelosis
Japanese レジオネラ感染NOS, レジオネラ感染, レジオネラカンセンNOS, レジオネラカンセン
Swedish Legionella-infektioner
Czech legionelóza, Legionelová infekce, Legionelové infekce, Legionelová infekce NOS
Finnish Legionelloosi
Croatian Not Translated[Legionellosis]
Polish Legioneloza, Legionelloza
Hungarian Legionella fertőzés k.m.n., Legionella fertőzés, Legionella fertőzések
Norwegian Legionellainfeksjoner, Legionellose

Ontology: Legionnaires' Disease (C0023241)

Definition (MEDLINEPLUS)

Legionnaires' disease is a type of pneumonia caused by bacteria. You usually get it by breathing in mist from water that contains the bacteria. The mist may come from hot tubs, showers, or air-conditioning units for large buildings. The bacteria don't spread from person to person.

Symptoms of Legionnaires' disease include high fever, chills, a cough, and sometimes muscle aches and headaches. Other types of pneumonia have similar symptoms. You will probably need a chest x-ray to diagnose the pneumonia. Lab tests can detect the specific bacteria that cause Legionnaires' disease.

Most people exposed to the bacteria do not become sick. You are more likely to get sick if you

  • Are older than 50
  • Smoke
  • Have a chronic lung disease
  • Have a weak immune system

Legionnaires' disease is serious and can be life-threatening. However, most people recover with antibiotic treatment.

Centers for Disease Control and Prevention

Definition (MSH) An acute, sometimes fatal, pneumonia-like bacterial infection characterized by high fever, malaise, muscle aches, respiratory disorders and headache. It is named for an outbreak at the 1976 Philadelphia convention of the American Legion.
Concepts Disease or Syndrome (T047)
MSH D007877
ICD9 482.84
ICD10 A48.1
SnomedCT 312403005, 154315008, 74881002, 266186009, 195889001, 269574000
English Disease, Legionnaire, Disease, Legionnaires', Infection, Legionella pneumophila, Infections, Legionella pneumophila, Legionella pneumophila Infection, Legionella pneumophila Infections, Legionnaire Disease, Legionnaires Disease, pneumophila Infection, Legionella, pneumophila Infections, Legionella, Legionnaire's Disease, Legionnaires' disease, LEGIONELLA PNEUMOPHILA INFECT, INFECT LEGIONELLA PNEUMOPHILA, LEGIONNAIRES DIS, LEGIONNAIRE DIS, Legionnaire's disease (diagnosis), Pneumonia legionella, Legionellal pneumonia, Legionnaire disease, Legionnaires' Disease [Disease/Finding], disease legionnaire's, legionella pneumonia, Disease;Legionnaires, disease legionnaires's, diseases legionnaire's, diseases legionnaires, legionnaire disease, pneumonia legionella, legionnaires disease, legionnaires' disease, Pneumonia due to Legionnaires' disease, Legionella, (Legionella) or (Legionnaire's disease) (disorder), (Legionella) or (Legionnaire's disease), Legionella pneumophila infection, Legionnaire's disease, Infection by Legionella pneumophilia, Legionella pneumonia, Infection by Legionella pneumophilia (disorder), Legionella pneumonia (disorder), Legionnaire's disease (disorder), Legionella pneumophila; infection, pneumonia (manifestation), Legionella pneumophila; infection, disease (or disorder); legionnaire's, infection; Legionella pneumophila, pneumonia (manifestation), infection; Legionella pneumophila, legionnaire's disease, legionnaire's; disease, Legionella pneumonia, NOS, Legionnaire's disease [Ambiguous], Legionnaires' Disease, Legionnaires disease
Italian Polmonite da Legionella, Infezione da legionella pneumophila, Malattia del legionario, Infezioni da Legionella pneumophila, Malattia dei legionari
Dutch legionairsziekte, Legionella pneumophila-infectie, Legionella pneumophila; infectie, pneumonie, Legionella pneumophila; infectie, aandoening; legionnair, infectie; Legionella pneumophila, pneumonie, infectie; Legionella pneumophila, legionnair; aandoening, Legionellose [veteranenziekte], Legionella-pneumonie, Legionairsziekte, Legionella-pneumophila-infectie, Veteranenziekte, Ziekte, legionairs-
French Pneumonie à Legionella, Infection à Legionella pneumophila, Pneumonie à Légionelles, Maladie des légionnaires, Infections à Legionella pneumophila, Maladie du légionnaire
German Legionella pneumophila Infektion, Legionaerskrankheit, Legionellose mit Pneumonie, Pneumonie durch Legionella, Legionella-pneumophila-Infektionen, Legionärskrankheit
Portuguese Doença do legionário, Infecção por Legionella pneumophila, Pneumonia por Legionella, Pneumonia a legionela, Doença dos Legionários, Infecções por Legionella pneumophila
Spanish Infección por Legionella pneumophila, Enfermedad de los legionarios, enfermedad de los legionarios (concepto no activo), infección por Legionella pneumophilia, enfermedad de los legionarios (trastorno), enfermedad de los legionarios, infección por Legionella pneumophila (trastorno), infección por Legionella pneumophila, neumonía de los legionarios (trastorno), neumonía de los legionarios, neumonía por Legionella, Neumonía por legionella, Enfermedad de los Legionarios, Infecciones por Legionella pneumophila
Japanese レジオネラ・ニューモフィラ感染, レジオネラ症, レジオネラ菌性肺炎, レジオネラショウ, レジオネラキンセイハイエン, レジオネラニューモフィラカンセン, 在郷軍人病, レジオネラ肺炎, レジオネラニューモフィーラ感染症, 肺炎-レジオネラ
Swedish Legionärssjuka
Czech legionářská nemoc, Legionářská nemoc, Infekce Legionella pneumophila, Legionelová pneumonie
Finnish Legioonalaistauti
Korean 리지오넬라병
Polish Choroba legionistów, Zakażenie Legionella pneumonophila
Hungarian Legionarius-betegség, Legionella pneumophila fertőzés, legionella pneumonia, Legionellosisos pneumonia
Norwegian Legionærsyken, Legionærsykdom, Pontiac-feber

Ontology: Pontiac fever (C0343528)

Concepts Disease or Syndrome (T047)
ICD10 A48.2
SnomedCT 240447002
English Nonpneumonic Legionnaires' disease [Pontiac fever], pontiac fever (diagnosis), Pontiac fever, Pontiac fever (disorder), Legionella pneumophila; infection, nonpneumonic, Pontiac; fever, disease (or disorder); legionnaire's, nonpneumonic, fever; Pontiac, infection; Legionella pneumophila, nonpneumonic
Italian Febbre di Pontiac
Japanese ポンティアック熱, ポンティアックネツ
German Legionellose ohne Pneumonie [Pontiac-Fieber], Pontiac-Fieber
Czech Pontiacká horečka
Korean 비폐렴성 리지오넬라병[폰티액 열]
Hungarian Pontiac-láz
Dutch Legionella pneumophila; infectie, niet-pneumonisch, Pontiac; koorts, aandoening; legionnair, niet-pneumonisch, infectie; Legionella pneumophila, niet-pneumonisch, koorts; Pontiac, Niet-pneumonische legionairsziekte [Pontiac-koorts], Pontiac-koorts
Spanish fiebre de Pontiac (trastorno), fiebre de Pontiac, Fibre de Pontiac
Portuguese Febre pontiac
French Fièvre de Pontiac

Ontology: Legionella pneumophila antigen (C0369588)

Concepts Immunologic Factor (T129)
SnomedCT 121073003
LNC LP38824-6, MTHU007227
English Legionella pneumophila Antigen, Legionella pneumophila Ag, Legionella Pneumophila Antigen, Legionella pneumophila antigen (substance), Legionella pneumophila antigen
Spanish antígeno de Legionella pneumophila (sustancia), antígeno de Legionella pneumophila