Psittacosis differential diagnosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aditya Govindavarjhulla, M.B.B.S. [2]; Omodamola Aje B.Sc, M.D. [3]

Overview

Psittacosis must be differentiated from other diseases that cause atypical pneumonia and febrile illness without localizing signs and extrapulmonary manifestations such as gastroenteritis, hepatitis, meningitis, or encephalitis. The three main diseases to differentiate psittacosis from are Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella infection, as they tend to have similar clinical manifestations that can only be differentiated by taking appropriate histories and laboratory investigations. There are other conditions to watch out for which may also present similarly to psittacosis.

Differentiating Psittacosis from other Diseases

The following diseases must be differentiated from psittacosis based on the presentation of cough, fever, myalgia, and shortness of breath.[1][2]

Disease Clinical Manifestations Lab findings Imaging findings Main treatment
Cough Sputum Dyspnea Sore throat Headache Confusion Diarrhea Hyponatremia Leukopenia Abnormal Liver function tests
Psittacosis ++ + +++ + Minimal +
  • No changes seen
Doxycycline
C.pneumoniae pneumonia + + + +++ ++ +
  • Minimal changes observed
Doxycycline, azithromycin
M. pneumoniae pneumonia ++ ++ ++ + Doxycycline
L. pneumophila infection + +++ +++ + ++ + ++ + ++
  • Often multifocal
Doxycycline
Influenza ++ ++ ++ ++ ++ ± ± Zanamivir, oseltamivir
Endocarditis ++ ++ + ± ±
  • Hazy opacities at lung bases bilaterally
Vancomycin
Coxiella burnetii infection ++ + ± +/- Minimal ± ± Doxycycline
Leptospirosis ++ + ++ + + ++ +++
  • Multiple ill-defined nodules in both lungs
Doxycycline, azithromycin, amoxicillin
Brucellosis ++ + ++ + ± ± ± Doxycycline, rifampin

Key;

+: Occurs in some cases

++: Occurs in many cases

+++: Occurs frequently

References

  1. Yung AP, Grayson ML (1988). "Psittacosis--a review of 135 cases". Med J Aust. 148 (5): 228–33. PMID 3343952.
  2. Raoult D, Marrie T (1995). "Q fever". Clin Infect Dis. 20 (3): 489–95, quiz 496. PMID 7756465.