Skip to content

Ctfviggmsmtser

Published: August 9, 2026Updated: August 14, 2026

A blood test that detects IgG antibodies against Colorado tick fever virus to determine past infection or immunity.

Quick summary

{"Detects IgG antibodies indicating previous Colorado tick fever infection","Typically becomes positive 2-3 weeks after infection","Positive result suggests prior exposure and potential immunity","Spread through the bite of infected Dermacentor ticks","Common in western mountainous regions of the United States"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 14, 2026Editorial policy

Key facts at a glance

LOINC
110783-8
Short code
CTF IgG
Synonyms
CTFV IgG Msmt Ser
Category
cardiac
Sample
serum
Container
Serum separator tube (SST/Gold top) or red top plain tube
Units
N/A
Ref low
0
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
Enzyme Immunoassay (EIA/ELISA) or Indirect Immunofluorescence Assay (IFA)
CPT
86635
SNOMED
371949004
Specimen volume
1.0 mL minimum serum volume required
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
50
Lipemia max
300
Icterus max
20
TAT
72–168 hours
Order
routine

What is this test?

The Colorado tick fever virus IgG antibody test is a blood test that looks for IgG antibodies specifically produced by your immune system in response to Colorado tick fever virus (CTFV) infection. IgG antibodies are the most common type of antibody in the blood and typically appear 2-3 weeks after initial infection, remaining in the body for long periods of time.

Why do I need this test?

This test may be ordered if you have symptoms suggestive of Colorado tick fever, especially if you have a history of tick exposure in endemic areas (primarily the Rocky Mountain regions of the United States). It helps determine whether you have had a previous infection with the virus, which can be useful for diagnosis, epidemiology studies, or to confirm immunity in high-risk individuals such as outdoor workers or frequent hikers.

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 it is analyzed using specialized immunoassay techniques to detect the presence and quantity of IgG antibodies against Colorado tick fever virus.

What do the results mean?

A positive IgG result indicates that you have been infected with Colorado tick fever virus at some point in the past, as IgG antibodies persist long after the initial infection. A negative result means no detectable IgG antibodies were found, which could indicate no prior infection, very early infection (before antibodies developed), or a very old infection where antibody levels have declined.

Reference range

Negative: < 1:64 titer; Equivocal: 1:64 titer; Positive: >= 1:64 titer. IgG antibodies indicate past infection or immunity to Colorado tick fever virus.N/A

Specimen: serum

No special preparation required. Fasting is not necessary. Inform laboratory of recent tick exposures or travel to endemic areas.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Who is at risk for Colorado tick fever?
People who live in or visit the Rocky Mountain regions of the United States, particularly those who engage in outdoor activities like hiking, camping, or fishing, are at higher risk. The disease is most common during the spring and summer months when tick activity is highest.
How is Colorado tick fever treated?
There is no specific antiviral treatment for Colorado tick fever. Supportive care is the mainstay of treatment, including rest, fluids, and medications to manage symptoms like fever and pain. Most people recover within a few weeks.
How can I prevent Colorado tick fever?
Prevention focuses on avoiding tick bites. Use insect repellents containing DEET, wear long sleeves and pants when in tick-prone areas, perform regular tick checks after outdoor activities, and promptly remove any attached ticks using fine-tipped tweezers.
Is this test different from the IgM antibody test?
Yes. IgM antibodies appear first during an infection (usually within the first 1-2 weeks) and indicate recent or current infection. IgG antibodies develop later and persist long-term, indicating past infection or immunity. Sometimes both tests are ordered together to help determine the timing of infection.
  1. 1
    CDC - Colorado Tick FeverSource
  2. 2
    Mayo Clinic Laboratories - Colorado Tick Fever Virus IgGSource
  3. 3
    Johns Hopkins Medicine - Tick-Borne DiseasesSource

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 14, 2026. · Read our editorial policy