Flowchart illustrating the idealised laboratory diagnosis of acute Q fever infection

 

Return to the NSW Control Guideline for public health units for Q fever.

Diagnosis

Acute, clinically compatible illness

  • PCR test:
    • Detected
      • Notification and public health follow-up
      • Confirmed case
    • Not detected
      • Send for initial (acute) serology
  • ​Initial (acute) serology:
    • Ab1 detected
      • ​Notification and public health follow-up
      • Possible case
      • Obtain follow-up (convalescent) sera 2-3 weeks after initial specimens
    • Ab1 not detected
      • Obtain follow-up (convalescent) sera 2-3 weeks after initial specimens​​​​
  • ​Paired sera testing (after obtaining convalescent sera 2-3 weeks after initial specimens​​​)
    • Ab1 detected​ (seroconversion) or 4-fold rise in titre
      • ​Confirmed case (updated from possible)
    • Ab1 not detected or <4-fold rise in titre2

References

  1. Serological patterns and the detection of Q fever-specific antibody (Ab) is dependent on the time from onset of illness, assay completed (i.e. IFA, CFT, EIA) and past exposure to the organism. Refer to section 7 and Appendix 5​ of the NSW Control Guidelines for detail. 
  2. Significant antibody titres may take 3-4 weeks from illness onset to appear in some cases. In cases not definitively confirmed by other means, a third sample is recommended, which should be collected 3-4 weeks after fever onset. 
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Page Updated: Tuesday 2 July 2019
Contact page owner: Communicable Diseases