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Beaumont Laboratory

Coxiella burnetti Antibodies, IgG

Q-Fever Antibody IgG, Phase I and II by IFA, ARUP #2012625, EPIC: LAB5993, SOFT: XCOX


Acute and convalescent specimens must be labeled as such; parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute samples. Please mark sample plainly as "acute" or "convalescent."

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: One plain Red-top tube. 

Physician Office/Drawsite Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 1.0 mL serum, refrigerated (2-8°C or 36-46°F). (Min: 0.1 mL)

Rejection Criteria

  • Hemolyzed specimens.
  • Severely lipemic specimens.
  • Specimens not collected and processed as indicated.


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 48 hours
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 1 year

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Sendout Laboratory with any questions.


Sent to ARUP Laboratories, Salt Lake City, UT.


Monday, Wednesday, Friday.
Results available in 2-6 days.

Reference Range

Phase I: Less than 1:16 - No antibody detected.
Phase II: Less than 1:16 - No antibody detected.

Test Methodology

Semi-Quantitative Indirect Fluorescent Antibody.


Single phase II IgG titers of 1:256 and greater are considered evidence of C. burnetii  infection at some time prior to the date of the serum specimen.  Phase I antibody titers of 1:16 and greater are consistent with chronic infection or convalescent phase of Q fever.  As in any serologic procedure, the demonstration of seroconversion or an increase in titer between acute and convalescent sera of at least fourfold is considered supportive evidence of current or recent C. burnetii infection.  This is true of phase I and or phase II.  A negative result at 1:16 argues against recent or active Q fever.

If either Phase I and/or Phase II result is indeterminate or positive, then titers will be added.

Clinical Utility

This assay aids in the diagnosis of Q-fever. Antibodies to Phase II predominate in acute disease and those to Phase I in chronic disease.

Clinical Disease

The clinical features of Q-fever include a fever (near 40°C) that  peaks in 2-4 days and then gradually declines for 1-2 weeks.  This initial fever may be accompanied by malaise, anorexia, myalgias, weakness, and intense headache.  Q-fever may also manifest as pneumonitis or bronchitis.  Endocarditis is an uncommon complication following a protracted latent phase.


Coxiella burnetii, the organism which causes Q-fever, is an obligate intracellular parasite (family Rickettsiaceae) with worldwide distribution.  It is unique within this group of organisms in that it undergoes a phase transition, similar to the smooth-rough lipopolysaccharide transitions seen in the enteric gram-negative bacteria.  Virulent isolates are of the phase I type, while serial passage in eggs or tissue culture is required for selection of the avirulent phase II transition. These phases are seologically distinguishable and quite useful in the seodiagnosis of both acute and chronic C. burnetii infections.

Incubation Period

Q-fever has an incubation period of approximately 2-3 weeks.


Dairy cattle , sheep, and cats are important reservoirs of C. burnetii. Recent evidence has also implicated rodents, as well as the cats that feed on them.  Infection in these animals in enzootic and nearly always inapparent. Transmission of Q-fever to humans is via inhalation of contaminated dust particles and aerosols, and via handling and ingestion of infected meat and milk.

CPT Code

86638x2, 86638 (per titer, if needed).

Test Codes

ARUP #2012625, EPIC: LAB5993, SOFT: XCOX

Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.