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psittacosis (ornithosis, parrot fever)
Etiology: Chlamydia psittaci
Epidemiology:
- bird exposure
- inhalation of urine or droppings from birds
- 1% of community-acquired pneumonia
Clinical manifestations:
1) incubation period 1-6 weeks
2) myalgias
3) fever
4) headache
5) pharyngitis
6) lethargy
7) confusion
8) delirium
9) splenomegaly (1-10%)
10) gastrointestinal symptoms (diarrhea)
11) community-acquired pneumonia: pulmonary symptoms are late & mild
Laboratory:
1) neutropenia (25%)
2) increased serum creatine kinase
3) serum sodium: hyponatremia
3) Chlamydophila psittaci antigen
4) Chlamydophila psittaci DNA
5) Chlamydophila psittaci serology
- four-fold rise in complement fixation titer over > 2 weeks
6) culture for Chlamydophila psittaci
- organism is fastidious, thus difficult to culture [2]
7) Chlamydophila psittaci in placenta by electron microscopy
Radiology:
- chest X-ray
a) patchy unilateral or bilateral lower lobe pneumonia
b) 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
Related
Chlamydophila psittaci (Chlamydia psittaci)
General
bacterial zoonosis
hypersensitivity pneumonitis; extrinsic allergic alveolitis; pigeon breeder's lung; bird fancier's lung; farmer's lung; allergic pneumonitis
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 798
- Medical Knowledge Self Assessment Program (MKSAP) 19.
American College of Physicians, Philadelphia 2021
- Medical Knowledge Self Assessment Program (MKSAP) 20
American College of Physicians, Philadelphia 2025
- Yin Q, Li Y, Pan H, et al.
Atypical pneumonia caused by Chlamydia psittaci during the COVID-19 pandemic.
Int J Infect Dis. 2022;122:622-627.
PMID: 35842216