Bacteria

Psittacosis

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Psittacosis, Chlamydophila psittaci, Chlamydia psittaci, Parrot Fever

  • See Also
  1. Atypical Pneumonia
  • Pathophysiology
  1. Organism
    1. Chlamydophila psittaci (Chlamydia psittaci)
    2. Bacteria found in wild and domestic birds (5-8% of otherwise healthy birds carry this infection)
  2. Transmission
    1. Inhalation of aerosolized infective particles
    2. Exposure to feces, urine, nasal secretions, feathers, and dust of infected birds
    3. Some pet owners kiss their birds, therefore transmitting the Bacteria
    4. Livestock, cats and dogs may act as intermediaries for human infection
    5. Human to human transmission is rare
  • Risk Factors
  • Transmission
  1. Pet owners of birds (e.g. Parrots, cockatiels, parakeets, macaws)
  2. Poultry farmers (turkeys are among the highest risk)
  3. Poultry processing plants
  4. Visit to aviary
  5. Veterinarians
  1. Subclinical, asymptomatic infection (common)
  2. Flu-like illness
  3. Mono-like illness (fever, Pharyngitis, Hepatosplenomegaly)
  4. Typhoid-like illness (fever, Bradycardia, Splenomegaly)
  5. Atypical Pneumonia (fever, non-productive cough, Headache)
    1. Most common presentation (and the one described on this page)
  1. Onset 1 to 3 weeks after exposure
  2. Constitutional
    1. Fever (>50% of cases) and Chills
    2. Myalgias
  3. Head and Neck
    1. Pharyngeal erythema
  4. Respiratory
    1. Non-productive cough (>50% of cases)
    2. Pulmonary rales
  5. Miscellaneous
    1. Headache (>30% of cases)
    2. Hepatomegaly
    3. Horder's Spots
      1. Similar to Typhoid Fever related Rose Spots
      2. Pink, blaching maculopapular rash
  • Complications (rare)
  1. Acute Respiratory Distress Syndrome (ARDS)
  2. Pericarditis
  3. Endocarditis
  4. Hepatitis
  5. Reactive Arthritis
  • Labs
  1. Complete Blood Count
    1. Slight Leukocytosis with Left Shift
  2. Liver Function Tests
    1. Increased Alkaline Phosphatase
  3. Blood and Sputum Cultures are not recommended due to risk of transmission
  • Diagnosis
  1. C. Psittaci titers
  • Differential Diagnosis
  1. See Atypical Pneumonia
  2. See Typhoid Fever
  1. Lobar Pneumonia is most common
  2. Atypical patterns also occur
  • Management
  1. Primary Management: Tetracyclines
    1. Doxycycline 100 mg orally twice daily for 7 to 10 days (preferred) OR
    2. Alternatives
      1. Tetracycline 500 mg orally four times daily for 7 to 10 days
      2. Minocycline 100 mg IV or orally daily for 7 to 10 days
  2. Primary Management: Macrolides (esp. pregnancy or age <8 years)
    1. Azithromycin 10 mg/kg (up to 500 mg) on Day 1, then 5 mg/kg (up to 250 mg) orally daily on Days 2-5
    2. Alternatives
      1. Clarithromycin 500 mg orally twice daily for 7 to 10 days
      2. Erythromycin
  3. Other alternative agents
    1. Fluoroquinolones
  • Prognosis
  1. Mortality
    1. Untreated case mortality approaches 20% (was 50% in the London 1930 epidemic)
    2. Treated case mortality <1%
  • References
  1. Schlossberg in Mandell (2005) Infectious Disease, Chapter 178
  2. Dembek (2023) Pathogens 12(9):1165 +PMID: 37764973 [PubMed]
  3. Schlossberg (1993) Arch Intern Med 153:2594-6 [PubMed]
  4. Yung (1988) Med J Aust 148:228-33 [PubMed]