psittacosis (ornithosis, parrot fever)

Etiology

Chlamydia psittaci

Epidemiology

• bird exposure
• inhalation of urine or droppings from birds
• 1% of community-acquired pneumonia

Clinical manifestations

• incubation period 1-6 weeks
• myalgias
• fever
• headache
• pharyngitis
• lethargy
• confusion
• delirium
• splenomegaly (1-10%)
• community-acquired pneumonia: pulmonary symptoms are late & mild

Laboratory

• neutropenia (25%)
• increased serum creatine kinase
• Chlamydophila psittaci antigen
• Chlamydophila psittaci DNA
• Chlamydophila psittaci serology
  • four-fold rise in complement fixation titer over > 2 weeks
• culture for Chlamydophila psittaci
  • organism is fastidious, thus difficult to culture
• Chlamydophila psittaci in placenta by electron microscopy

Radiology

• chest X-ray
  • patchy unilateral or bilateral lower lobe pneumonia
  • occasional pleural effusions are small

Differential diagnosis

• pigeon breeder's or bird fancier's lung (hypersensitivity pneumonitis)
• Chlamydophila pneumoniae
• Mycoplasma pneumoniae

Management

• treat as hypersensitivity pneumonitis unless symptoms of bacterial pneumonia
  • remove offending agent (parrot)
  • clinical observation

More general terms

• bacterial zoonosis
• hypersensitivity pneumonitis

Additional terms

• Chlamydophila psittaci (Chlamydia psittaci)

Patient information

psittacosis patient information