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Rickettsial Antibody Battery, IgG

Updated

10/5/2009

Other Names
Rocky Mountain Spotted Fever, RMSF, Q Fever, Murine typhus, Ricketsia rickettsii, Rickettsia typhi
How to Order
Check the Rickettsial Battery box on the Virology/Immunology Request (Form 42)
Availability
All Clients
Methodology
Indirect Immunofluorescence Assay (IFA)
Performed
Weekly
Time to Reporting
2 to 7 working days after receipt of specimen.
CPT Code
86757


Specimen Collection Details

Collection
One 7 ml red top tube or serum separator tube (SST). Heat inactivated non-citrated plasma is also an acceptable specimen type.
Optimal Volume
Blood:7 mL; Serum or non-citrated Plasma 1-2 mL
Minimum Volume
Blood:3 mL; Serum or non-citrated Plasma 0.5 mL
Handling
After blood clots, keep specimen refrigerated until transport. DO NOT FREEZE. If possible remove the serum from the clot as soon as possible. Sample must be tested within 7 days of collection.
Transport
Refrigerated at 2-8° C.
Rejection Criteria
Hyperlipemic, grossly hemolyzed, or contaminated specimens; specimens received without proper patient identifiers on specimen tube and/or request form; and specimens received with requests without submitter information will be rejected.
Comments
The most convincing serologic evidence of recent rickettsial infection is a four-fold rise in antibody titer between the serum obtained during the acute phase of the illness and the serum obtained during the convalescent phase. Single titers of 1:64 are considered borderline, and in such instances it is best to obtain a second specimen for testing. If this is not possible, then one should interpret the
results cautiously and with several factors in mind, including the timing of specimen collection and the clinical and epidemiological histories of the patient.
  For Q fever, single serum titers of 1:256 are considered minimum positive titers. If a single serum was obtained during the early acute phase of the illness (< 10 days), negative results are not exceptional and a convalescent serum drawn at least 3 weeks after onset should be tested to rule out Q fever.
  A non-reactive (titer < 1:32) in a single serum test cannot be used to rule out infection. In order to rule out infection, a second specimen should be collected two to three weeks after the first specimen and tested in parallel with the first specimen in order to rule out infection. As noted in the previous section, a negative result would not be unexpected in the early acute phase of the disease. Properly timed collection of specimens is very important in this test.
  This test procedure only detects IgG antibodies to the specific rickettsial agents. It is therefore possible that a test specimen could yield a “false” negative result during the early acute phase of infection if that specimen only contained IgM antibodies to a given agent. This is another reason that a second specimen, drawn two to three weeks after the first, must be tested in order to rule out rickettsial infection.
  Reference Range Rocky Mountain Spotted Fever specimen #1
Rocky Mountain Spotted Fever specimen #2
Murine Typhus specimen #1
Murine Typhus specimen #2
Q Fever Phase 1 specimen #1
Q Fever Phase 1 specimen #2
Q Fever Phase 2 specimen #1
Q Fever Phase 2 specimen #2
Single Titers - RMSF and Murine Typhus
Single Titers - Q Fever < 1:32 titer
< 1:32 titer
< 1:32 titer
< 1:32 titer
< 1:32 titer
< 1:32 titer
< 1:32 titer
< 1:32 titer
1:32 not significant
1:64 borderline
1:128 evidence of prior infection
1:256 evidence of prior infection