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A blood test that detects antibodies against Rickettsia typhi (murine typhus) and Rickettsia spotted fever group to help diagnose rickettsial infections.
{"The test uses a blood sample to detect IgM (recent infection) and IgG (past infection) antibodies","It helps diagnose murine typhus and spotted fever rickettsial diseases","Results are typically available within a few days to a week","Positive IgM usually indicates recent infection, while IgG suggests past exposure or immunity","Early testing is important as antibodies may take 7-14 days to appear"}
Key facts at a glance
- LOINC
- 41876-4
- Short code
- RICK-PANEL
- Synonyms
- R typhi and SF IgG+IgM Pnl Ser
- Category
- cardiac
- Sample
- serum
- Container
- Serum separator tube (SST) or red top plain tube
- Units
- N/A
- Ref low
- 4
- Ref high
- 5.9
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Enzyme-linked immunosorbent assay (ELISA) or Indirect Immunofluorescence Assay (IFA)
- CPT
- 86757 (Rickettsia antibody, each)
- SNOMED
- 122442004, 186747009
- Specimen volume
- 1.0-2.0 mL serum minimum
- Stability
- Room temperature: 24-48 hours; Refrigerated (2-8°C): 5-7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 48–168 hours
- Order
- routine
What is this test?
The Rickettsia Typhi and Rickettsia Spotted Fever Group IgG and IgM Panel is a blood test that looks for antibodies your immune system makes in response to Rickettsia bacteria. Rickettsia typhi causes murine typhus (also called endemic typhus), while the spotted fever group includes various bacteria that cause diseases like Rocky Mountain spotted fever. The test measures two types of antibodies: IgM (which appear first and indicate recent infection) and IgG (which develop later and indicate past infection or immunity).
Why might I need this test?
Your doctor may order this test if you have symptoms of a rickettsial infection, especially if you have been exposed to areas where these infections are common. Symptoms typically include fever, headache, rash (often starting on wrists and ankles), and muscle pain. Rickettsial infections are often transmitted through bites from infected fleas, ticks, or mites. Common risk factors include outdoor activities, travel to endemic areas, or contact with rodents.
How is the test performed?
A healthcare professional will draw a small blood sample from a vein in your arm. The blood is collected into a tube and sent to a laboratory for analysis. The test looks for specific antibodies (IgM and IgG) against Rickettsia typhi and spotted fever group bacteria in your blood serum. You do not need to fast before this test, and there are no special preparations required.
Understanding your results
Results are typically reported as positive or negative for IgG and IgM antibodies against each Rickettsia group. A positive IgM result usually indicates a recent infection (within the past few weeks). A positive IgG result may indicate a past infection or immunity from previous exposure. However, timing is important—antibodies may not appear until 7-14 days after symptoms begin, so early testing may be negative even if you are infected. Your doctor will interpret results in context with your symptoms, exposure history, and physical examination.
Are there any risks?
The risks associated with this blood test are minimal and include minor bruising at the needle site, lightheadedness, or rare infection. These side effects are usually temporary and resolve quickly. The test itself does not pose any significant health risks.
Reference range
IgG: < 1:64 titer or < 4.0 index considered negative; 1:64 to 1:128 titer or 4.0-5.9 index considered equivocal; >= 1:256 titer or >= 6.0 index considered positive. IgM: < 1:64 titer or < 4.0 index considered negative; 1:64 titer or 4.0-5.9 index considered equivocal; >= 1:128 titer or >= 6.0 index considered positive. A four-fold rise in titers between acute and convalescent samples (2-4 weeks apart) indicates recent infection.N/A
No fasting required. Inform laboratory of recent infections, immunosuppressive therapy, or prior rickettsial exposures as these may affect results. Acute phase sample should be collected within first week of symptoms, convalescent sample 2-4 weeks later.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
How long does it take to get results?
Do I need to fast before this test?
What happens if my test is negative?
Can this test tell me if I'm immune?
How are rickettsial infections treated?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 14, 2026. · Read our editorial policy