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

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Etiology

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

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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

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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

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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)

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Treatment

• Tetracylines: effective
• Chloramphenicol: effective

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Prognosis

• Course is generally uncomplicated and benign

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References

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