eMedicine Specialties > Infectious Diseases > Lower Respiratory Tract Infections

Psittacosis

Author: Klaus-Dieter Lessnau, MD, FCCP, Clinical Associate Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory; Director of Research in Pulmonary Medicine, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital
Coauthor(s): Farhad Arjomand, MD, Pulmonary Fellow, Department of Internal Medicine, Division of Pulmonary and Critical Care, Brooklyn Hospital Center, Cornell University School of Medicine
Contributor Information and Disclosures

Updated: Jun 27, 2008

Introduction

Background

Psittacosis is an infection caused by the obligatory intracellular bacterium Chlamydia psittaci. The term psittacosis is derived from the Greek word for parrot, psittakos, and was first used by Morange in 1892.

This bacterium can infect parrots, parakeets, canaries, and other avian species (eg, turkeys, pigeons, ducks). Another term for this infection is ornithosis, which describes the infection caused by nonpsittacine birds.

The largest epidemic occurred in 1930 and affected 750-800 individuals. This epidemic led to the isolation of C psittaci in several laboratories in Europe and the United States.

Psittacosis is an occupational disease of zoo and pet-shop employees, poultry farmers, and ranchers. Human-to-human transmission is rare, but possible. These cases may cause more severe disease than avian-acquired psittacosis.

Psittacosis is probably underdiagnosed.

Pathophysiology

The primary route for infection is through the respiratory system. Infection develops after organisms from aerosolized dried avian excreta or respiratory secretions from sick birds are inhaled. C psittaci attaches to the respiratory epithelial cells. After the initial inoculation, the organism spreads via the blood stream to the reticuloendothelial system. Subsequently, secondary bacteremia causes lung infection.

Humans may acquire disease by handling sick birds. Mouth-to-beak resuscitation has also been implicated in transmission. Transient exposure to infected birds may cause symptomatic infection, even in visitors to pet shops.

Frequency

United States

Reports show up to 200 cases of psittacosis annually. From 1988-97, the US Centers for Disease Control and Prevention (CDC) received 766 reports of psittacosis, which is probably an underestimate of the actual number of cases because psittacosis is difficult to diagnose, is covered by macrolide antimicrobials (which may be used empirically for therapy of community-acquired pneumonia), and often goes reported.

From 1988-2003, 935 human cases of psittacosis were reported to the CDC.1

International

Psittacosis is found worldwide. The incidence seems to be increasing in developed countries, which is correlated to the import of exotic birds.

Mortality/Morbidity

The mortality rate prior to the advent of antimicrobial treatment was approximately 15-20%. The mortality rate is less than 1% with appropriate antibiotic therapy.

Race

No race predilection is observed.

Sex

No sex predilection is observed.

Age

Psittacosis occurs in all age groups, including children. The infection is more common among individuals in the middle decades of life.

Breed

Certain strains of C psittaci infect sheep, goats, and cows and may cause chronic infection and abortion.

  • Wild birds such as falcons have caused disease through nasal or fecal secretions.
  • Mowing lawns without a grass catcher has been found to be a risk factor.
  • Most diseases resulted from exposure to infected pet birds, usually cockatiels, parakeets, parrots, and macaws.

Clinical

History

The incubation period is generally 5-14 days. The longest observed incubation time was 54 days. The predominant presentation is respiratory tract infection with constitutional symptoms. Clinical findings are variable.

  • Constitutional
    • Fever (50-90%)
    • Chills
    • Malaise
  • Respiratory
    • Cough (50-90%), usually not productive
    • Pleuritic chest pain (rare)
    • Dyspnea
    • Sore throat and mild pharyngitis (common)
    • Epistaxis (common)
  • Gastrointestinal
    • Nausea and vomiting (uncommon)
    • Abdominal pain (uncommon)
    • Diarrhea (rare)
    • Jaundice (rare)
  • Neurological
    • Severe headache (common)
    • Photophobia (common)
    • Agitation and lethargy
  • Dermatological - Includes facial rash (Horder spots)

Physical

Disease may range from mild insidious presentations to severe pneumonia that requires mechanical ventilation.

  • Respiratory
    • Nonspecific auscultatory findings that often underestimate clinical and radiographic findings may develop.
    • Patients may develop fatal pulmonary embolism and pulmonary infarction.
    • Pleural effusion is rare.
  • Cardiac
    • Relative bradycardia is common.
    • Physicians may observe pericarditis, culture-negative endocarditis, and myocarditis.
  • Gastrointestinal
    • Splenomegaly occurs in 10-70% of patients, depending on the study.
    • When present, this sign suggests psittacosis in patients with pneumonia.
  • Neurological
    • Patients may develop meningitis, encephalitis, seizures, and Guillain-Barré syndrome, but these are rare.
    • Cerebrospinal fluid (CSF) findings are usually normal.
  • Dermatological
  • Hematological
  • Renal symptoms include acute glomerulonephritis and tubulointerstitial nephritis.
  • Musculoskeletal symptoms include reactive arthritis that is usually polyarticular. Rarely, rhabdomyolysis has been observed.2
  • Stages of disease progression

1.      Flulike syndromes without radiographic abnormalities

2.      Mild-to-moderate pneumonia

3.      Severe pneumonia

4.      Acute respiratory failure, sepsis, and septic shock

Causes

Psittacosis is an infectious disease caused by the obligatory intracellular bacterium C psittaci.

  • C psittaci is associated with psittacine birds and poultry.
  • Psittacosis is an occupational disease of poultry farmers, pet-shop workers, and veterinarians.
  • Relapses may occur.
  • Because psittacosis is a bacterial disease, major protective immunity is unlikely to develop after a single episode of disease. The exact risk of recurrence upon reexposure is unknown. It is reasonable to advise avoidance of infected birds.

More on Psittacosis

Overview: Psittacosis
Differential Diagnoses & Workup: Psittacosis
Treatment & Medication: Psittacosis
Follow-up: Psittacosis
References
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References

  1. Smith KA, Bradley KK, Stobierski MG, et al. Compendium of measures to control Chlamydophila psittaci (formerly Chlamydia psittaci) infection among humans (psittacosis) and pet birds, 2005. J Am Vet Med Assoc. Feb 15 2005;226(4):532-9. [Medline].

  2. Matsushima H, Takayanagi N, Ubukata M, et al. [A case of fulminant psittacosis with rhabdomyolysis]. Nihon Kokyuki Gakkai Zasshi. Jul 2002;40(7):612-6. [Medline].

  3. Committee of the National Association of State Public Health Veterinarians. Compendium of measures to control Chlamydia psittaci infection among humans (psittacosis) and pet birds (avian chlamydiosis), 2000. Centers for Disease Control and Prevention. Morbidity Mortality Weekly Reports. 2000;49:3-17. [Medline].

  4. Coutts II, Mackenzie S, White RJ. Clinical and radiographic features of psittacosis infection. Thorax. Jul 1985;40(7):530-2. [Medline].

  5. Crosse BA. Psittacosis: a clinical review. J Infect. Nov 1990;21(3):251-9. [Medline].

  6. Cunha BA. Atypical pneumonias. Clinical diagnosis and empirical treatment. Postgrad Med. Oct 1991;90(5):89-90, 95-8, 101. [Medline].

  7. Cunha BA. Atypical pneumonias. In: Conn RB, Borer WZ, Snyder JW, eds. Current Diagnosis. WB Saunders Co; 1996.

  8. Cunha BA. The atypical pneumonias: clinical diagnosis and importance. Clin Microbiol Infect. May 2006;12 Suppl 3:12-24. [Medline].

  9. Cunha BA. The chlamydial pneumonias. Drugs Today (Barc). Dec 1998;34(12):1005-12. [Medline].

  10. Cunha BA, Ortega AM. Atypical pneumonia. Extrapulmonary clues guide the way to diagnosis. Postgrad Med. Jan 1996;99(1):123-8, 131-2. [Medline].

  11. De Schrijver K. A psittacosis outbreak in Belgian customs officers. Euro Surveillance. 1995;Sep:3. [Medline].

  12. Elliott JH. Psittacosis. A flu like syndrome. Aust Fam Physician. Aug 2001;30(8):739-41. [Medline].

  13. Entrican G, Brown J, Graham S. Cytokines and the protective host immune response to Chlamydia psittaci. Comp Immunol Microbiol Infect Dis. Jan 1998;21(1):15-26. [Medline].

  14. Gherman RB, Leventis LL, Miller RC. Chlamydial psittacosis during pregnancy: a case report. Obstet Gynecol. Oct 1995;86(4 Pt 2):648-50. [Medline].

  15. Gregory DW, Schaffner W. Psittacosis. Semin Respir Infect. Mar 1997;12(1):7-11. [Medline].

  16. Heddema ER, Kraan MC, Buys-Bergen HE, et al. A woman with a lobar infiltrate due to psittacosis detected by polymerase chain reaction. Scand J Infect Dis. 2003;35(6-7):422-4. [Medline].

  17. Hughes P, Chidley K, Cowie J. Neurological complications in psittacosis: a case report and literature review. Respir Med. Oct 1995;89(9):637-8. [Medline].

  18. Jaton K, Greub G. [Chlamydia: diagnostic and treatment]. Rev Med Suisse. Mar 30 2005;1(13):895-8, 901-3. [Medline].

  19. Johnson DH, Cunha BA. Atypical pneumonias. Clinical and extrapulmonary features of Chlamydia, Mycoplasma, and Legionella infections. Postgrad Med. May 15 1993;93(7):69-72, 75-6, 79-82. [Medline].

  20. Kirchner JT. Psittacosis. Is contact with birds causing your patient's pneumonia?. Postgrad Med. Aug 1997;102(2):181-2, 187-8, 193-4. [Medline].

  21. MacLaren G, Pellegrino V, Butt W, et al. Successful use of ECMO in adults with life-threatening infections. Anaesth Intensive Care. Oct 2004;32(5):707-10. [Medline].

  22. Matsui T, Nakashima K, Ohyama T, et al. An outbreak of psittacosis in a bird park in Japan. Epidemiol Infect. Apr 2008;136(4):492-5. [Medline].

  23. Nash TW, Murray HW. The atypical pneumonias. In: Fishman AP, ed. Pulmonary diseases and disorders. Vol 2. 2nd ed. New York, NY: McGraw-Hill; 1998:1619-24.

  24. Oldach DW, Gaydos CA, Mundy LM, et al. Rapid diagnosis of Chlamydia psittaci pneumonia. Clin Infect Dis. Sep 1993;17(3):338-43. [Medline].

  25. Raso Tde F, Godoy SN, Milanelo L, et al. An outbreak of chlamydiosis in captive blue-fronted Amazon parrots (Amazona aestiva) in Brazil. J Zoo Wildl Med. Mar 2004;35(1):94-6. [Medline].

  26. Schlossberg D. Chlamydia psittaci (psittacosis). In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 5th ed. Philadelphia, Pa: Churchill Livingstone; 2000:2004-6.

  27. Schlossberg D, Delgado J, Moore MM, et al. An epidemic of avian and human psittacosis. Arch Intern Med. Nov 22 1993;153(22):2594-6. [Medline].

  28. Stamm WE. Chlamydial infection: psittacosis. In: Braunwald E, et al, eds. Harrison's Principles of Internal Medicine. 14th ed. New York, NY: McGraw Hill; 1998:1055-64.

  29. Telfer BL, Moberley SA, Hort KP, et al. Probable psittacosis outbreak linked to wild birds. Emerg Infect Dis. Mar 2005;11(3):391-7. [Medline].

  30. The latest from the IVD industry December 2004. Chlamydia--pathogens that are still often underestimated. Clin Lab. 2005;51(3-4):225-9. [Medline].

  31. Tong CY, Sillis M. Detection of Chlamydia pneumoniae and Chlamydia psittaci in sputum samples by PCR. J Clin Pathol. Apr 1993;46(4):313-7. [Medline].

  32. Verweij PE, Meis JF, Eijk R, et al. Severe human psittacosis requiring artificial ventilation: case report and review. Clin Infect Dis. Feb 1995;20(2):440-2. [Medline].

  33. Wong KH, Skelton SK, Daugharty H. Utility of complement fixation and microimmunofluorescence assays for detecting serologic responses in patients with clinically diagnosed psittacosis. J Clin Microbiol. Oct 1994;32(10):2417-21. [Medline].

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Further Reading

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Keywords

psittacosis, ornithosis, parrot fever, Chlamydia psittaci, C psittaci, avian-acquired psittacosis

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Contributor Information and Disclosures

Author

Klaus-Dieter Lessnau, MD, FCCP, Clinical Associate Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory; Director of Research in Pulmonary Medicine, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital
Klaus-Dieter Lessnau, MD, FCCP is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Medical Association, American Society for Artificial Internal Organs, American Thoracic Society, Physicians for Social Responsibility, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Farhad Arjomand, MD, Pulmonary Fellow, Department of Internal Medicine, Division of Pulmonary and Critical Care, Brooklyn Hospital Center, Cornell University School of Medicine
Disclosure: Nothing to disclose.

Medical Editor

Kenneth C Earhart, MD, Deputy Head, Disease Surveillance Program, United States Naval Medical Research Unit #3
Kenneth C Earhart, MD is a member of the following medical societies: American College of Physicians, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, and Undersea and Hyperbaric Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Richard B Brown, MD, FACP, Chief, Division of Infectious Diseases, Baystate Medical Center; Professor, Department of Internal Medicine, Tufts University School of Medicine
Richard B Brown, MD, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Chest Physicians, American College of Physicians, American Medical Association, American Society for Microbiology, Infectious Diseases Society of America, and Massachusetts Medical Society
Disclosure: Nothing to disclose.

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

 
 
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