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Diagnosis, Treatment, and Prevention

Diagnostic Methods

Diagnosis of psittacosis can be difficult. Laboratories use several methods to detect Chlamydia psittaci infection. Some tests are only available in specialized laboratories.  See the table below for advantages and disadvantages of different methods for diagnosing psittacosis. Laboratories typically run tests on sputum specimens or swabs of the nasopharynx and oropharynx or serum, depending on the method used. In severe cases, other specimen types may be used. When additional or specialized testing is necessary, local or state public health laboratories may be able to either provide diagnostic support or forward specimens to CDC. See CDC’s Test Directory for additional information.

Advantages and disadvantages of select C. psittaci diagnostic methods

Advantages and disadvantages of select C. psittaci diagnostic methods
Method Advantages Disadvantages
Culture
  • Provides clinical isolates for genotyping, antimicrobial susceptibility testing, and next generation sequencing
  • Time-consuming
  • Technically difficult; requires specialized expertise
  • Must be cultivated within a tissue culture, mice, or chick embryo
  • Few laboratories perform
Serologic test (e.g., complement fixation, microimmunofluorescent antibody test)
  • Tests are available in many clinical laboratories
  • Cross-reactivity with other Chlamydia species may occur
  • Requires acute and convalescent samples, and delays confirmation
Real-time polymerase chain reaction (PCR)1
  • Rapid detection
  • Sensitive and specific
  • Results can be obtained in time to guide treatment decisions
  • Useful for strain typing
  • Requires specialized reagents and equipment

Treatment

Chlamydia psittaci are sensitive to both macrolides and tetracyclines. However, tetracyclines are the drugs of choice, unless contraindicated as they are in children, due to reported macrolide failures.

Prevention

Patient isolation and prophylaxis of contacts are usually not indicated, as person-to-person transmission of C. psittaci is rare.

Most states require clinicians to report cases of psittacosis in humans to the appropriate health authorities. Timely diagnosis and reporting may aid in identifying the source of the infection and controlling the spread of disease.

Educate patients about the importance of handling birds and cleaning bird cages safely. Refer birds suspected as the source of human infection to veterinarians for evaluation and treatment.

References

Resources

1 The National Notifiable Diseases Surveillance System case definition currently considers an illness with characteristic symptoms and detection of C. psittaci nucleic acid in patient specimen via real-time polymerase chain reaction (PCR) to be a probable, but not confirmed, case.

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