Rickettsia typhi is the etiologic agent of both epidemic and endemic typhus.
Tests generally appear in the order most useful for common clinical situations
| Test name: Rickettsia typhi (Typhus Fever) Antibodies, IgG & IgM by IFA |
| ARUP #: 0050384 |
| Methodology: Semi-Quantitative Indirect Fluorescent Antibody |
| Use: Confirm presence of Rickettsia typhi |
| Limitations: Initial testing may not be helpful; base treatment on clinical and other laboratory assessment While the presence of IgM antibodies suggests current or recent infection, low levels of IgM antibodies may occasionally persist for >12 months post-infection Any antibody reactivity to Rickettsia typhi antigen should also be considered group reactive for the typhus fever group (R. prowazekii) |
| Follow-up: If test results are equivocal, repeat testing in 10-14 days |
| Test name: Febrile Antibodies Panel |
| ARUP #: 2001789 |
| Methodology: Semi-Quantitative Direct Agglutination/Semi-Quantitative Indirect Fluorescent Assay/Qualitative ImmunoDOT |
| Use: Use to confirm presence of disease; not recommended for initial testing Panel includes IgM R. typhi antibody by ELISA testing, as well as testing for antibodies to Brucella, R. rickettsii, Salmonella O and H antigens |
| Limitations: Base treatment decision on clinical and other laboratory assessments Cross reactivity with Brucella and Salmonella |
| Test name: CBC with Platelet Count & Automated Differential |
| ARUP #: 0040003 |
| Methodology: Automated Cell Count with Flow Cell Differential |
| Use: Non-specific testing for R. typhi Shows thrombocytopenia in 40% of cases |
| Test name: Urea Nitrogen, Serum or Plasma |
| ARUP #: 0020023 |
| Methodology: Quantitative Spectrophotometry |
| Use: Non-specific testing for R. typhi Elevated in ~30% of cases |
| Test name: Hepatic Function Panel |
| ARUP #: 0020416 |
| Methodology: Refer to individual components. |
| Use: Non-specific testing for R. typhi Bilirubin elevated in ~20% of cases |
| Test name: Creatinine, Serum or Plasma |
| ARUP #: 0020025 |
| Methodology: Quantitative Enzymatic |
| Use: Non-specific testing for R. typhi |
| Test name: Rickettsia typhi (Typhus Fever) Antibody, IgG by IFA |
| ARUP #: 0050381 |
| Methodology: Semi-Quantitative Indirect Fluorescent Antibody |
| Comments: |
| Test name: Rickettsia typhi (Typhus Fever) Antibody, IgM by IFA |
| ARUP #: 0050383 |
| Methodology: Semi-Quantitative Indirect Fluorescent Antibody |
| Comments: |
| Test name: Weil-Felix Test |
| ARUP #: 0093143 |
| Methodology: Direct Agglutination |
| Comments: Non-specific test that is no longer useful |