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 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.
For this disease/condition, Confirmed and Probable case statuses are included in the released case count.
Comment
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 realtime polymerase chain reaction (rtPCR) has been
developed and validated in avian specimens but has not yet been validated for
use in humans (1).