Ordering Recommendation

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

Mnemonic
TYPHU M
Methodology

Semi-Quantitative Indirect Fluorescent Antibody

Performed

Sun-Sat

Reported

1-3 days

New York DOH Approval Status
This test is New York DOH 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: 0.3 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)

Reference Interval
Less than 1:64 Negative - No significant level of IgM antibody detected.
1:64 or greater 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.

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.

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