Q Fever

Epidemiology

  • Occurs worldwide
  • High incidence in farming communities of Europe, North America, and Australia
  • Infects a wide variety of domestic and wild animals, rodents, and insects
  • Outbreaks: in tanneries, dairies (even in some individuals within 2-3 miles of a dairy), wool-rendering plants, in lab personnel, and in household members exposed to an infected cat or dog during parturition

Etiology

  • Coxiella burnetti
  • Organism is highly resistant to drying
  • Maintains activity after months of dormancy in contaminated soil

Physiology

  • Transmission
    • Exposure to Urine/Feces/Placenta of Infected Animals: most commonly cows, sheep, and goats
    • Exposure to Unpasteurized Milk from Infected Animal: most commonly cows, sheep, and goats
  • Incubation Period: 2-4 wks

Diagnosis

  • Sputum GS/Cult+Sens:
  • CXR/Chest CT Pattern: 60% of cases have radiographic evidence of pleuropulmonary involvement
    • Segmental Infiltrates: mass-like consolidation can occur
    • Peribronchial, Alveolar, Atypical Pneumonia-Like Pattern:
  • Serology:
  • CBC:
    • WBC Count: normal
    • Thrombocytopenia
  • Elevated LFT s (suggestive of granulomatous hepatitis)
  • LP: CSF is normal

Clinical

  • Necrotizing Pneumonia (see Necrotizing Pneumonia, [[Necrotizing Pneumonia]])
  • Atypical Pneumonia Syndrome (see Pneumonia, [[Pneumonia]]): usually mild symptoms, developing within 2-4 wks after exposure
    • Dry Cough with Crackles: usually develops days after onset
      • Streaky hemoptysis may be seen in some cases
    • Fever/Shaking Chills:
    • Myalgias:
    • Headache:
    • Stiff Neck:
    • Relative Bradycardia:
    • Conjunctivitis:
    • Hepatosplenomegaly:
    • Anorexia:
  • Pharyngitis/Purulent Sputum/Hemoptysis/Profound Dyspnea/Chest Pain: all are unusual
  • Rash is typically absent (unlike other Rickettsial infections)

Treatment

  • Tetracylines: effective
  • Chloramphenicol: effective

Prognosis

  • Course is generally uncomplicated and benign

References

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