Causes, incidence, and risk factors

This disease is usually seen between March and September. Most cases occur in April, May, and June.

Risk factors are recent outdoor activity and recent tick bite.

Colorado tick fever is seen most often in Colorado. Up to 15% of campers have been exposed to the virus that causes the disease. The disease is much less common in the rest of the United States.

Symptoms

Symptoms of Colorado tick fever most often start 3 to 6 days after getting the tick bite. A sudden fever continues for 3 days, goes away, then comes back 1 to 3 days later for another few days. Other symptoms include:

• Generalized weakness

• Headache behind the eyes

• Muscle aches

• Nausea and vomiting

• Rash (may be light-colored)

• Sensitivity to light ( photophobia)

• Skin pain

• Sweating

Signs and tests

Antibody tests can be done to confirm the infection. Other blood tests may include:

• Complete blood count (CBC)

• Creatine kinase

• Liver function tests

Treatment

Make sure the tick is fully removed from the skin. Take a pain reliever if necessary. Do not give aspirin to children. Aspirin has been linked with Reye syndrome in children. It may also cause other problems in Colorado tick fever.

If complications develop, treatment will be aimed at controlling the symptoms.

Expectations (prognosis)

Colorado tick fever usually goes away by itself and is not dangerous.

Complications

Complications include aseptic meningitis, encephalitis, and hemorrhagic fever.

Calling your health care provider

Call your health care provider if you are unable to fully remove a tick embedded in the skin, if you or your child develop symptoms of this disease, if symptoms worsen or do not improve with treatment, or if new symptoms develop.

Prevention

When walking or hiking in tick-infested areas, wear closed shoes, long sleeves, and tuck long pants into socks to protect the legs. Wear light-colored clothing, which shows ticks more easily than darker colors, making them easier to remove.

Check yourself and your pets frequently. If you find ticks, remove them immediately by using a tweezers, pulling carefully and steadily. Insect repellent may be helpful.

References

1. DeBiasi RL, Tyler KL. Coltiviruses and Seadornaviruses. In:Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 149.
2. Naides SJ. Arthropod-borne viruses causing fever and rash syndromes. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 390.

Review Date: 10/6/2012.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.