ARUP's Laboratory Test Directory

Rickettsia typhi (Typhus Fever) Antibody, IgM by IFA : 0050383

Mnemonic: TYPHU M

Methodology: Semi-Quantitative Indirect Fluorescent Antibody
Performed: Tue, Fri
Reported: 1-5 days
Specimen Required: Collect: 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: Refrigerated.

Unacceptable Conditions: Contaminated, hemolyzed, or severely lipemic, specimens.

Stability (collection to initiation of testing): After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)
Reference Interval:
< 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: This test is 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).  Seroconversions or an increase between acute and convalescent IgG and IgM titers of at least fourfold is considered strong evidence of recent infection.

While the presence of IgM antibodies suggests recent infection, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection.
CPT Code(s): 86757
Cross References: Typhus Fever Antibody (Rickettsia typhi (Typhus Fever) Antibody, IgM by IFA)