Ordering Recommendation

Confirm presence of Rickettsia typhi. Panel test (IgG and IgM) is preferred. Requires comparison of acute- to convalescent-phase serology.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Serum Separator Tube (SST).

Specimen Preparation

Separate from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP standard transport tube. (Min: 0.4 mL) Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens.

Storage/Transport Temperature


Unacceptable Conditions

Contaminated, hemolyzed, or severely lipemic specimens.


Mark specimens plainly as "acute" or "convalescent."


After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)


Semi-Quantitative Indirect Fluorescent Antibody (IFA)




1-3 days

Reference Interval

Test Number
Reference Interval
  Typhus Fever Antibody, IgG Less than 1:64

Interpretive Data

Antibody reactivity to Rickettsia typhi antigen should be considered group-reactive for the Typhus Fever group, which includes Rickettsia prowazekii.

Seroconversion between acute and convalescent sera is considered strong evidence of recent infection. The best evidence for infection is a significant change (fourfold difference in titer) on two appropriately timed specimens, where both tests are done in the same laboratory at the same time. Acute-phase specimens are collected during the first week of illness and convalescent-phase samples are generally obtained 2-4 weeks after resolution of illness. Ideally these samples should be tested simultaneously at the same facility. If the sample submitted was collected during the acute phase of illness, submit a marked convalescent sample within 25 days for paired testing.

Unit Of Measure
Typhus Fever Antibody, IgG Less than 1:64
1:256 or greater
Negative - No significant level of IgG antibody detected.
Equivocal - Questionable presence of IgG antibody detected.  Repeat testing in 10-14 days may be helpful.
Positive - Presence of IgG antibody detected, suggestive of current or past infection.

Compliance Category



Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0050381 Typhus Fever Antibody, IgG 5324-9
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Murine Typhus Antibodies, IgG
  • R typhi IgG antibody
  • Typhus Fever Group IgG Antibody
Rickettsia typhi (Typhus Fever) Antibody, IgG by IFA