Psittacosis / Ornithosis (Chlamydophila psittaci) 2010 Case Definition

NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

CSTE Position Statement(s)

09-ID-13

Clinical Description

Psittacosis is an illness characterized by fever, chills, headache, myalgia, and a dry cough with pneumonia often evident on chest x-ray. Severe pneumonia requiring intensive-care support, endocarditis, hepatitis, and neurologic complications occasionally occur.

Laboratory Criteria For Diagnosis

Isolation of Chlamydophila psittaci from respiratory specimens (e.g., sputum, pleural fluid, or tissue), or blood, OR
Fourfold or greater increase in antibody (Immunoglobulin G [IgG]) against C. psittaci by complement fixation (CF) or microimmunofluorescence (MIF) between paired acute- and convalescent-phase serum specimens obtained at least 2-4 weeks apart , OR
Supportive serology (e.g. C. psittaci antibody titer [Immunoglobulin M (IgM)] of greater than or equal to 32 in at least one serum specimen obtained after onset of symptoms), OR
Detection of C. psittaci DNA in a respiratory specimen (e.g. sputum, pleural fluid or tissue) via amplification of a specific target by polymerase chain reaction (PCR) assay.

Case Classification

Probable

An illness characterized by fever, chills, headache, cough and myalgia that has either:

Supportive serology (e.g. C. psittaci antibody titer [Immunoglobulin M, IgM] of greater than or equal to 32 in at least one serum specimen obtained after onset of symptoms), OR
Detection of C. psittaci DNA in a respiratory specimen (e.g. sputum, pleural fluid or tissue) via amplification of a specific target by polymerase chain reaction (PCR) assay.

Confirmed

An illness characterized by fever, chills, headache, cough and myalgia, and laboratory confirmed by either:

Isolation of C. psittaci from respiratory specimens (e.g., sputum, pleural fluid, or tissue), or blood, OR
Fourfold or greater increase in antibody (Immunoglobulin G [IgG]) against C. psittaci by complement fixation (CF) or microimmunofluorescence (MIF) between paired acute- and convalescent-phase serum specimens obtained at least 2-4 weeks apart.

Comments

Although MIF has shown greater specificity to C. psittaci than CF, positive serologic findings by both techniques may occur as a result of infection with other Chlamydia species and should be interpreted with caution. To increase the reliability of test results, acute- and convalescent-phase serum specimens should be analyzed at the same time in the same laboratory. A real-time polymerase chain reaction (rtPCR) has been developed and validated in avian specimens but has not yet been validated for use in humans.¹

References

Mitchell, S.L., Wolff, B.J., Thacker, W.L., Ciembor, P.G., Gregory, C.R., Everett, K.D., Ritchie, B.W., & Winchell, J.M. (2009). Genotyping of Chlamydophila psittaci by real-time PCR and high-resolution melt analysis. J Clin Microbiol, 47(1),175-181.

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Last Reviewed: April 16, 2021

Source: Office of Public Health Data, Surveillance, and Technology