Rickettsia rickettsii IgG & IgM Abs
Test Mnemonic
ROCKY
CPT Codes
- 86757 - QTY (2)
Aliases
- Rocky Mountain Spotted Fever
- Tick-Borne Diseases
Includes
- R. rickettsii IgG Abs
- R. rickettsii IgM Abs
Performing Laboratory
ARUP
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL | Serum | SST (Gold) | Refrigerated | Separate serum from cells ASAP or within 2 hours of collection and transfer to standard aliquot tube. Parallel testing is preferred and convalescent specimens MUST be received within 30 days from receipt of the acute specimens. Label specimens plainly as 'acute' or 'convalescent.' |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.4 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | After separation from cells: 48 hours |
| Refrigerated | After separation from cells: 2 weeks |
| Frozen | After separation from cells: 1 year (Avoid repeated freeze/thaw cycles) |
Days Performed
Sun - Sat
Turnaround Time
2 - 4 days
Methodology
| Name | Description |
|---|---|
| Semi-Quantitative Indirect Fluorescent Antibody |
Reference Range
| R. rickettsii IgG Abs | |||||
|---|---|---|---|---|---|
| Sex | Age From | Age To | Type | Range | Range Unit |
| Normal | Low Positive: 1:64 - 1:128 | titer | Normal | Negative: <1:64 | titer | Normal | Positive: 1:256 and greater | titer |
| R. rickettsii IgM Abs | |||||
| Sex | Age From | Age To | Type | Range | Range Unit |
| Normal | Negative: <1:64 | titer | Normal | Positive: 1:64 and greater | titer |
Special Info
Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Contaminated, hemolyzed, or severely lipemic specimens are unacceptable. This test is New York DOH approved.
Clinical Info
This is the preferred test for acute or convalescent phase of disease. Acute and convalescent titers are often necessary. Antibody reactivity to Rickettsia rickettsii antigen should be considered Spotted Fever group reactive. Other organisms within the group include R. akari, R. conorrii, R. australis, and R. sibirica. Seroconversion, a fourfold or greater rise in antibody titer, between acute and convalescent sera is considered strong evidence of recent infection. 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 labeled convalescent sample within 25 days for paired testing. The CDC does not use IgM results for routine diagnostic testing of Rocky Mountain Spotted Fever, as the response may not be specific for the agent (resulting in false positives) and the IgM response may be persistent from past infection.