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Psittacosis/Ornithosis

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Reporting Obligations

Confirmed and suspected cases shall be reported to the local Health Unit.

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Epidemiology

Aetiologic Agent

Psittacosis/Ornithosis is caused by Chlamydophila psittaci (formerly Chlamydia psittaci), an obligate intracellular bacterial pathogen.

Clinical Presentation

Onset of psittacosis is usually abrupt with fever, headache, photophobia, myalgia, upper or lower respiratory tract symptoms, and non-productive cough. Respiratory symptoms are often mild when compared with pneumonia demonstrable on thoracic radiographs. Complications can occur occasionally and include encephalitis, myocarditis and thrombophlebitis. Mild forms of the illness may be mistaken for common respiratory infection and may go unnoticed or undiagnosed.

Modes of Transmission

Infection is generally acquired by inhaling dust from dried feces or dried ocular and nasal secretions from infected birds. Handling of plumage or dust from feathers of infected birds are also modes of exposure. Direct contact with birds is not required; rare person-to-person spread has occurred.

Incubation Period

From 1–4 weeks.

Period of Communicability

Birds may shed the agent intermittently and sometimes continuously for weeks or months. Rarely communicable person-to-person.

Risk Factors/Susceptibility

Susceptibility is general; persons in contact with infected birds are at highest risk and older adults may be more severely affected; there is no evidence that persons with antibodies are protected, post infective immunity is incomplete or transitory.

Diagnosis and Laboratory Testing

Laboratory Confirmation

Any of the following will constitute a confirmed case of psittacosis/ornithosis:

  • Isolation of infectious agent from clinical specimen (This should be done in a Containment level 3 facility, being a risk level 3 agent in Canada.)
  • A significant (i.e., fourfold or greater) rise in antibody response towards Chlamydia psittaci with specimen collection ≥ 2–3 weeks apart.
  • Positive for nucleic amplification testing (NAAT) for C.psittaci specific targets.
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Treatment and Case Management

Treatment with antibiotics is under the direction of the attending health care provider. Isolation of case is not required. Instruct the patient on using proper hand hygiene and proper cough etiquette.

Patient Information

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Additional Resources

Heymann, D.L. Control of Communicable Disease Manual (19th Ed.), Washington, American Public Health Association, 2008.

References

Ministry of Health and Long-Term Care, Infectious Diseases Protocol, 2019.