Colorado tick fever is a viral infection spread by a bite from an infected Dermacentor andersoni wood tick. This species of tick is more commonly referred to as the Rocky Mountain Wood tick.
All ticks are parasites that feed on blood. Ticks are more common at higher elevations. Colorado tick fever is more prevalent in Colorado than in the rest of the United States. The disease is limited to the Western US and Canada. Incidence of Colorado tick fever is highest between February and October, with 90 percent of cases being reported between April and July. You are at increased risk if you spend time outdoors in tick-infested areas.
Symptoms begin within three to six days after a tick bite and include fever, chills, headache, nausea, and vomiting. These 3 to 6 days are referred to as the period of incubation. This means that symptoms immediately after a tick bite are not likely caused by tick fever. In most cases, symptoms resolve on their own within 10 days. Most patients make a full recovery.
Colorado tick fever is sometimes referred to as “mountain tick fever” or “American mountain fever.”
Symptoms of Colorado tick fever include:
- sudden fever up to 105 degrees Fahrenheit
- headache behind the eyes
- light sensitivity (photophobia)
- muscle aches
- skin pain
- anorexia (loss of the desire to eat)
- nausea and vomiting
- abdominal pain
- general weakness and fatigue
- rash this is faint and occasional
A fever associated with Colorado tick fever generally lasts two to three days, and then subsides for a few days, returning for another 48 hours or so. For most people, symptoms disappear completely in about ten days.
Symptoms of Colorado tick fever are similar to those of other infectious diseases. Consult with your doctor if you develop severe symptoms of Colorado tick fever, your symptoms don’t improve within a week, or if you cannot completely remove a tick embedded in your skin.
Potential serious complications of this infection include meningitis (brain infection), encephalitis (brain inflammation) and hemorrhagic fevers. Hemorrhagic fever seriously damages your blood vessels and is a life threatening condition.
However, fatalities are rarely caused by Colorado tick fever.
Diagnosis is usually based on a physical examination and laboratory tests, including:
Complement Fixation Antibody Test
This test measures the activity of certain proteins (called antibodies) in your blood. These antibodies do not appear until the third week of the disease.
Immunofluorescence Antibody Test
This test identifies certain antibodies or antigens in blood serum.
Complete Blood Count
This blood test is a broad screening that measures white blood cells, red blood cells, and platelets to diagnose a disease.
This is a blood test to determine levels of the enzyme in the blood.
Liver Function Tests
Since Colorado tick fever can affect your liver, your doctor may want to run tests to assess your liver function.
Polymerase Chain Reaction
A specialized molecular biology test called a “polymerase chain reaction” can identify the existence of the virus in your through its DNA.
First, the tick must be removed. In most cases, home treatment with fever and pain reducers is sufficient. Rarely, as discussed above, complications can include:
- encephalitis (an inflammation of the brain)
- hemorrhagic fever (infections that may be life threatening)
- aseptic meningitis (linings of the brain become inflamed)
Hospitalization may be required if complications are present or illness is severe.
You should never attempt to remove ticks using lit matches or petroleum jelly. These methods may cause the tick to release the pathogen that causes illness.
The safest way to remove a tick from your skin is with fine-tipped tweezers as follows:
- If possible, wear rubber gloves rather than bare hands. If you don’t have gloves, use a paper towel or tissue over your fingers.
- Grab the tick as close to your skin as you can and pull up in a steady motion. Using a twisting or jerking motion may cause the tick to break and leave parts in your skin. Try not to squeeze the tick’s body.
- Wash your hands and the bite mark with soap and water.
Save the tick in a plastic bag in your freezer, making note of the date. If you become ill, the tick can be used in making a diagnosis.
You can decrease your chances of tick bites by avoiding areas that are known to be tick-infested. When you are in an area that might have ticks, be sure to wear proper clothing such as closed shoes, long pants tucked into socks, and long sleeves shirts. When outdoors, cover all extremities and avoid areas that are known for higher degrees of tick infestation. Ticks will show up better on clothes that are light in color. Insect repellents containing DEET are most effective for keeping ticks away.
Make sure you check yourself, your children, and your pets frequently for ticks when you are outside in areas where ticks live. Ticks that are embedded in the skin should be removed with tweezers immediately.
In most cases, people with Colorado tick fever make a complete recovery with no lasting side effects. Previous infection with Colorado tick fever may provide immunity against reinfection (Arizona Department of Health Services).