Colorado Tick Fever

Disease Overview

Colorado Tick Fever is a rare viral disease transmitted by ticks that commonly inhabit the western United States. Major symptoms may include fever, headaches, muscle aches, and/or generalized discomfort (myalgia). The symptoms usually last for about a week and resolve on their own.

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Synonyms

CTF
Mountain Fever
Mountain Tick Fever

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Signs & Symptoms

Colorado Tick Fever typically has a sudden onset about five days after a tick bite. It usually occurs at moderate altitudes during spring or early summer. The symptoms are flu-like and may include chills, headache, increased sensitivity to light (photophobia), fatigue, nausea, vomiting, and a lack of appetite. Muscle pain occurs, especially in the legs and back. There may be a slight, reddish rash, and the spleen can become enlarged (splenomegaly). Fever may rise sharply for two or three days and then subside only to return after a day or two (biphasic fever). The second fever typically subsides after 2 to 4 days.

In very rare childhood cases, severe illness involving the central nervous system may occur. Symptoms may include acute inflammation of the membranes around the brain (aseptic meningitis) and/or spinal cord (encephalitis).

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Causes

Colorado Tick Fever is a rare viral disease caused by a virus belonging to the Coltivirus family. It is transmitted to humans through the bite of the wood tick (Dermacentor andersoni).

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Affected populations

Colorado Tick Fever is a rare viral disease that affects males and females in equal numbers. Most reported cases have occurred in the Rocky Mountain area of the United States and the western provinces of Canada. Several hundred cases of this disease are reported each year in these areas where the wood tick lives (endemic). However, it is possible that many additional cases are misdiagnosed or undiagnosed.

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Disorders with Similar Symptoms

Symptoms of the following disorders can be similar to those of Colorado Tick Fever. Comparisons may be useful for a differential diagnosis:

Lyme Disease is an infectious inflammatory disease transmitted by a tick (Borrelia burgdorferi). The early symptoms may include a characteristic red, round skin lesion (bull-eye rash), fever, muscle pain, chills, headache, nausea, and/or vomiting. Swollen and/or painful joints may also occur. Neurological abnormalities may develop (e.g., meningitis, facial paralysis, involuntary muscle movements) but usually resolve completely without treatment. (For more information on this disorder, choose “Lyme” as your search term in the Rare Disease Database.)

Rocky Mountain Spotted Fever is an acute disease caused by bacterium (Rickettsia) and transmitted by ticks. Initially, symptoms begin suddenly and may include fever, severe headache, and muscle pain. Nausea, vomiting, and abdominal pain may also occur. A rash typically begins on the wrists and ankles and spreads toward the center of the body. Early diagnosis and treatment are vital to avoid serious complications. (For more information on this disorder, choose “Rocky Mountain Spotted Fever” as your search term in the Rare Disease Database.)

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Standard Therapies

The diagnosis of Colorado Tick Fever is confirmed by isolation of the virus from the blood. Treatment for Colorado Tick Fever is symptomatic and may include acetaminophen to relieve headaches and muscle pain.

The most effective means of preventing Colorado Tick Fever is the use of protective clothing or chemical tick repellents when visiting endemic areas during the spring and summer. Individuals should inspect themselves frequently for ticks and quickly remove them when found.

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Clinical Trials and Studies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

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References

TEXTBOOKS

Bennett JC, Plum F., eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA: W.B. Saunders Co; 1996:1805-07.

Fields BN, et al., Fields Virology, 2nd ed. New York, NY: Raven Press; 1990:1421-27.

REVIEW ARTICLES

Friedman AD., Hematologic manifestations of viral infections. Pediatr Ann. 1996;25:555-60.

Myers SA, et al., Dermatologic manifestations of arthropod-borne diseases. Infect Dis Clin North Am. 1994;8:689-712.

JOURNAL ARTICLES

Attoui H, et al., Serologic and molecular diagnosis of Colorado tick fever viral infections. Am J Trop Med Hyg. 1998;59:763-68.

Attoui H, et al., Complete nucleotide sequence of Colorado tick fever virus segments M6, S1 and S2. J Gen Virol. 1997;78:2895-99.

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Programs & Resources

RareCare^® Assistance Programs

NORD strives to open new assistance programs as funding allows. If we don’t have a program for you now, please continue to check back with us.

Additional Assistance Programs

MedicAlert Assistance Program

NORD and MedicAlert Foundation have teamed up on a new program to provide protection to rare disease patients in emergency situations.

Learn more https://rarediseases.org/patient-assistance-programs/medicalert-assistance-program/

Rare Disease Educational Support Program

Ensuring that patients and caregivers are armed with the tools they need to live their best lives while managing their rare condition is a vital part of NORD’s mission.

Learn more https://rarediseases.org/patient-assistance-programs/rare-disease-educational-support/