Rickettsia Spotted Fever Group Antibody Blood Test
This blood test detects IgM antibodies against Rickettsia bacteria that cause spotted fever, helping diagnose recent or current infection.
{"Detects IgM antibodies indicating recent or current Rickettsia infection","Sample collected through a simple blood draw from a vein","Positive results suggest infection within the past 2-3 weeks","Symptoms include fever, headache, and characteristic rash","Early treatment with antibiotics is important for better outcomes"}
Key facts at a glance
- LOINC
- 7999-6
- Short code
- RICK-IgM
- Synonyms
- Rick SF IgM Ser-aCnc
- Category
- cardiac
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red top tube
- Units
- N/A
- Ref low
- 4
- Ref high
- 5.9
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Enzyme-linked immunosorbent assay (ELISA) or Indirect Immunofluorescence Assay (IFA)
- CPT
- 86757
- SNOMED
- 128188008
- Specimen volume
- 1.0-2.0 mL of serum
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 72 hours; Frozen (-20°C or below): 30 days
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 48–168 hours
- Order
- routine
This test checks a sample of your blood for antibodies that your immune system makes in response to bacteria in the Rickettsia spotted fever group, helping your doctor find out whether symptoms such as fever, rash, headache, or muscle aches are caused by this type of tick-borne infection.
The Rickettsia Spotted Fever Group IgM Antibody test is a blood test that looks for IgM antibodies in your blood. IgM antibodies are the first type of antibodies your immune system produces when fighting a new infection. This test helps doctors determine if you have a current or recent infection caused by Rickettsia bacteria belonging to the spotted fever group.
Rickettsia spotted fever refers to a group of bacterial infections spread to people through the bite of infected ticks. In the United States, the best known and most serious of these illnesses is Rocky Mountain spotted fever, which can cause high fever, headache, nausea, and a distinctive rash, and may become dangerous without prompt treatment.
Rickettsia spotted fever group includes several related diseases caused by bacteria transmitted to humans through bites from infected ticks, mites, or fleas. Examples include Rocky Mountain spotted fever, Mediterranean spotted fever, and Japanese spotted fever. These diseases can cause serious illness if not treated promptly.
A trained healthcare professional will draw a small sample of blood, usually from a vein in your arm, using a needle. The procedure takes only a few minutes and feels like a routine blood draw. The sample is then sent to a laboratory, where it is examined for antibodies, and your doctor will share the results with you once testing is complete.
A healthcare professional will draw a small sample of blood from a vein in your arm. The blood sample is then sent to a laboratory where technicians test it for the presence of IgM antibodies specific to Rickettsia spotted fever group bacteria. You may experience slight pain or bruising at the needle site, but serious complications are rare.
A positive result means your blood contains antibodies against Rickettsia bacteria, which suggests a current or past spotted fever infection. A negative result can occur early in the illness because antibodies take time to develop, so your doctor may order repeat testing. Results are always interpreted together with your symptoms, any recent tick exposure, and your overall health before a diagnosis is made and treatment is planned.
A positive IgM result typically indicates that you have a current or recent infection with Rickettsia bacteria. IgM antibodies usually appear within 1-2 weeks of infection and can remain in your blood for several weeks to months. A negative result may mean you do not have an infection, or the infection is too early to detect. Your doctor will interpret the results together with your symptoms and other test findings.
Reference range
Negative: <1:64 titer or <4.0 units; Equivocal: 1:64 titer or 4.0-5.9 units; Positive: >=1:128 titer or >=6.0 unitsN/A
No special preparation required. Inform physician of any recent infections, travel history, or exposure to tick-borne areas.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The Rickettsia Spotted Fever Group IgM Antibody test is primarily used to diagnose acute rickettsial infections. Early detection is crucial because these infections can progress rapidly and lead to severe complications, including damage to blood vessels, organ failure, and in some cases, cardiac involvement. The test helps differentiate current/recent infections from past exposures, which is important for guiding treatment decisions and implementing public health measures.
Frequently asked questions
Do I need to fast before this test?
How long does it take to get results?
What are the symptoms of spotted fever rickettsiosis?
Is this test always accurate?
How is rickettsial infection 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 17, 2026. · Read our editorial policy