Colorado Tick Fever Virus IgG and IgM Antibodies Blood Test
This blood test detects IgG and IgM antibodies against Colorado tick fever virus in a sample of your blood. Your immune system produces these antibodies to fight the virus, and measuring them helps your healthcare provider determine whether you have a recent or past infection with Colorado tick fever so that appropriate care can be planned.
{"Colorado tick fever is a viral infection spread by tick bites","IgM antibodies indicate recent infection, IgG antibodies indicate past infection or immunity","Symptoms include fever, headache, muscle pain, and rash","The test requires a simple blood draw","Treatment focuses on symptom relief as the virus typically resolves on its own"}
Key facts at a glance
- LOINC
- 35684-0
- Short code
- CTFV IgG/IgM
- Synonyms
- CTFV IgG+IgM Pnl Ser
- Category
- cardiac
- Sample
- serum
- Container
- Serum separator tube (SST) or red top plain tube
- Units
- N/A
- Ref low
- 0.9
- Ref high
- 1.1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Enzyme-linked immunosorbent assay (ELISA) or Indirect Immunofluorescence Assay (IFA) for detection of IgG and IgM antibodies against Colorado tick fever virus
- CPT
- 86635
- SNOMED
- 371949004
- Specimen volume
- 1.0-2.0 mL of serum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–168 hours
- Order
- routine
What is this test?
The Colorado tick fever virus IgG and IgM panel is a blood test that detects antibodies your immune system produces in response to Colorado tick fever virus (CTFV). This test looks for two types of antibodies: IgM (which appears early in infection) and IgG (which develops later and remains long-term).
Why is this test performed?
Your healthcare provider may order this test if you have symptoms of Colorado tick fever, especially if you have been in areas where tick bites are common. The test helps confirm whether your symptoms are caused by this specific viral infection.
What is Colorado tick fever?
Colorado tick fever is a viral disease transmitted through the bite of an infected Rocky Mountain wood tick. It is most common in the western United States, particularly in mountainous areas. Symptoms typically appear 3-7 days after a tick bite and may include high fever, severe headache, muscle aches, fatigue, and sometimes a rash.
How is the test performed?
A healthcare professional will draw a small blood sample from a vein in your arm. The sample is then sent to a laboratory where technicians will analyze it for the presence of IgG and IgM antibodies against Colorado tick fever virus.
What do the results mean?
A positive IgM result typically indicates a recent infection, as IgM antibodies appear first during an immune response. A positive IgG result suggests a past infection or that your body has developed immunity. Your healthcare provider will interpret your results along with your symptoms and medical history.
Reference range
Negative: <1:16 titer or <0.9 index value; Equivocal: 1:16 to 1:32 or 0.9-1.1 index value; Positive: >1:32 titer or >1.1 index value. IgM positive indicates recent or acute infection; IgG positive indicates past exposure or immunity.N/A
No fasting required. No special preparation needed. Inform laboratory of recent tick exposure or travel to endemic areas.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Colorado tick fever is generally a self-limiting illness that resolves within 2-3 weeks. However, in rare cases, complications can occur. Detection of IgG and IgM antibodies helps confirm the diagnosis, which is important for proper management and to rule out other conditions with similar symptoms such as Rocky Mountain spotted fever or other tick-borne diseases.
Frequently asked questions
Do I need to fast before this test?
How long does it take to get results?
Is Colorado tick fever serious?
How can I prevent Colorado tick fever?
Sources
- 1
- 2
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 16, 2026. · Read our editorial policy