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
Collect

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

Refrigerated.

Unacceptable Conditions

Contaminated, hemolyzed, or severely lipemic, specimens.

Remarks

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

Stability

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

Methodology

Semi-Quantitative Indirect Fluorescent Antibody (IFA)

Performed

Sun-Sat

Reported

1-3 days

Reference Interval

Test Number
Components
Reference Interval
  Typhus Fever Antibody, IgM 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.


Component
Unit Of Measure
Interpretation
Typhus Fever Antibody, IgM Less than 1:64
1:64 or greater
Negative - No significant level of IgM antibody detected.
Positive - Presence of IgM antibody to detected, which may indicate a current or recent infection; however, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection.

Compliance Category

FDA

Note

Hotline History

N/A

CPT Codes

86757

Components

Component Test Code* Component Chart Name LOINC
0050383 Typhus Fever Antibody, IgM 5325-6
* 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.

Aliases

  • R typhi IgM antibody
  • Typhus Fever Group IgM Antibody
Rickettsia typhi (Typhus Fever) Antibody, IgM by IFA