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Ctfvabserql

Published: August 9, 2026Updated: August 10, 2026

A blood test that detects antibodies against the Colorado tick fever virus, which is transmitted through tick bites.

Quick summary

{"Checks for immune response to Colorado tick fever virus in your blood","Helps diagnose current or past infection with this tick-borne virus","The virus is transmitted by Rocky Mountain wood ticks","Antibodies typically appear 2-4 weeks after infection","Common symptoms include fever, headache, and muscle pain"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
26653-6
Short code
CTFV Ab
Synonyms
CTFV Ab Ser Ql
Category
cardiac
Sample
serum
Container
Serum separator tube (SST) or plain red top tube
Units
N/A
Ref low
0
Ref high
0
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Enzyme-linked immunosorbent assay (ELISA) or Immunofluorescence assay (IFA)
CPT
86635
SNOMED
371949004
Specimen volume
1-2 mL of serum
Stability
Room temperature: 8 hours; Refrigerated (2-8°C): 5 days; Frozen (-20°C or below): 30 days
Hemolysis max
50
Lipemia max
100
Icterus max
20
TAT
48–168 hours
Order
routine

What is this test?

The Colorado tick fever virus antibody test is a blood test that looks for antibodies—proteins your immune system makes to fight infections—in your serum. This test specifically checks for antibodies against the Colorado tick fever virus (CTFV), a virus transmitted through the bite of an infected Rocky Mountain wood tick. The presence of these antibodies indicates that your body has been exposed to the virus at some point.

Why might I need this test?

Your doctor may order this test if you have symptoms of Colorado tick fever, especially if you have been in areas where Rocky Mountain wood ticks are common (typically the western United States and southwestern Canada). Symptoms usually appear 2-4 days after a tick bite and include sudden fever, severe headache, chills, muscle pain, and sometimes a rash. Because symptoms can resemble other illnesses, this test helps confirm whether the infection is caused by the Colorado tick fever virus.

How is the test performed?

A healthcare professional will draw a small blood sample from a vein in your arm. This sample is then sent to a laboratory where technicians test it for the presence of specific antibodies (IgM and IgG) against the Colorado tick fever virus. IgM antibodies typically appear first and indicate a recent infection, while IgG antibodies develop later and may remain in your blood for years, suggesting past exposure.

Reference range

Negative or Not Detected - No detectable Colorado tick fever virus IgM or IgG antibodiesN/A

Specimen: serum

No special preparation required. Inform laboratory of recent tick exposure, travel history to endemic areas, or symptoms consistent with Colorado tick fever such as fever, headache, myalgia, or rash.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

What are the symptoms of Colorado tick fever?
Symptoms typically begin 2-4 days after a tick bite and include high fever, severe headache, chills, muscle aches (myalgia), fatigue, and sometimes a rash. Some people may also experience nausea, vomiting, or abdominal pain. The fever often comes in waves, and symptoms can last for several weeks if left untreated.
How is Colorado tick fever treated?
There is no specific antiviral treatment for Colorado tick fever. Care is mainly supportive—rest, fluids, and medications to reduce fever and pain (like acetaminophen). Most people recover within 2-3 weeks, but fatigue can persist longer. Severe cases may require hospitalization for IV fluids and monitoring.
How can I prevent Colorado tick fever?
Prevention focuses on avoiding tick bites: use insect repellent with DEET, wear long sleeves and pants when hiking in tick-prone areas, perform regular tick checks after outdoor activities, and promptly remove any attached ticks. Creating tick-safe zones in your yard and treating pets with tick prevention can also help.
What do my test results mean?
A positive result means antibodies to Colorado tick fever virus were found in your blood, indicating you have been infected with the virus. A negative result means no antibodies were detected, but this could also mean you were infected too recently for antibodies to develop (the 'window period'). Your doctor will interpret results alongside your symptoms and exposure history.
Where is Colorado tick fever found?
Colorado tick fever is primarily found in the western United States and southwestern Canada, particularly in mountainous areas at elevations of 4,000 to 10,000 feet where Rocky Mountain wood ticks live. Most cases occur in spring and summer when people are most active outdoors.
  1. 1
    Colorado Tick Fever - CDCSource
  2. 2
    Colorado Tick Fever - MedlinePlusSource
  3. 3
    Tick-Borne Diseases - Merck ManualSource

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.

Medical Disclaimer

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 10, 2026. · Read our editorial policy