Rickettsia typhi (Typhus Fever) Antibodies, IgG & IgM by IFA
Ordering Recommendation
Confirm presence of Rickettsia typhi. Requires comparison of acute- to convalescent-phase serology.
Semi-Quantitative Indirect Fluorescent Antibody
Tue, Fri
1-5 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Serum separator tube.  
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.1 mL) Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Mark specimens plainly as acute or convalescent.  
Storage/Transport Temperature
Unacceptable Conditions
Contaminated, hemolyzed, or severely lipemic specimens.  
After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)  
Reference Interval
Test Number Components Reference Interval
0050381Rickettsia typhi (Typhus Fever) Antibody, IgG by IFA < 1:64  Negative -​ No significant level of Rickettsia typhi IgG antibody detected.
1:64-​1:128  Equivocal -​ Questionable presence of Rickettsia typhi IgG antibody detected.  Repeat testing in 10-​14 days may be helpful.
≥ 1:256  Positive -​ Presence of IgG antibody to Rickettsia typhi detected, suggestive of current or past infection.
0050383Rickettsia typhi (Typhus Fever) Antibody, IgM by IFA < 1:64  Negative -​ No significant level of Rickettsia typhi IgM antibody detected.
≥1:64  Positive -​ Presence of IgM antibody to Rickettsia typhi detected, suggestive of recent infection.
Interpretive Data
These tests are for antibodies to Rickettsia typhi. Any antibody reactivity to Rickettsia typhi antigen should, however, also be considered group-reactive for the Typhus Fever group (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.

While the presence of IgM antibodies suggests current or recent infection, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection.  
CPT Code(s)
86757 x2
Component Test Code*Component Chart NameLOINC
0050381Typhus Fever Antibody, IgG5324-9
0050383Typhus Fever Antibody, IgM5325-6
* 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
  • R. typhi antibodies
  • Typhus Fever Group Antibody, IgG and IgM, Serum