Everything You Need to Know About Colorado Tick Fever

Colorado Tick Fever

Colorado tick fever (CTF) – also referred to as mountain fever – is a rare condition.

According to the Columbia University Irving Medical Center, only 10 cases of CTF are reported in the U.S. each year.

However, if you live in or visit an area where the Rocky Mountain wood tick is found, developing this condition is possible.

This is why you should know what to do if you’ve been bitten or you experience symptoms like weakness, headaches, nausea, and vomiting.

In this article, we look at the causes, symptoms, and treatment options for Colorado tick fever to help you better understand this condition.

Causes of Colorado Tick Fever

Colorado tick fever is a viral disease caused by the bite of a Rocky Mountain wood tick. The virus is transmitted to humans through the saliva of infected ticks.

This tick is found in much of the western United States, including Colorado, Utah, Montana, and Wyoming.

According to the Centers for Disease Control and Prevention (CDC), these ticks are typically found at elevations of 4,000 to 10,000 feet above sea level.

In very rare cases, the Colorado tick fever virus can also be caused by a blood transfusion — which we will explain later in this article.

The condition is typically seen between March and September, with most cases occurring in April, May, and June.

This is when the Rocky Mountain wood tick is most active, making it more likely that you will be bitten during outdoor activities during this period.

Symptoms of Colorado Tick Fever

Typically, the first symptoms develop within 1 to 14 days after the tick bite.

You may then develop a biphasic fever, which can make it feel like your symptoms are coming and going.

According to the CDC, biphasic fever will make you feel better for several days after your initial symptoms and then feel worse for a second period.

It’s worth noting that this is a rare viral disease, and another condition could cause the symptoms below.

This makes it important to seek medical advice if you suspect you have Colorado tick fever.

Fever and chills

The virus caused by the tick bite triggers the immune system to release various molecules to help fight it. This can cause a fever, which is a common response to most viral infections.

As the body’s temperature rises from the fever, people with this condition may also experience chills.

Weakness and muscle aches

The immune system’s response to the virus can affect the tissues and organs in the body, leading to muscle aches and weakness for several weeks.

The energy expended by the body to combat the viral infection can also cause feelings of weakness.


Headaches commonly accompany a fever, which is likely why you’ll experience this symptom. Fevers can also lead to dehydration, which can cause a headache.

Lastly, the immune system’s release of cytokines in response to the virus can also play a role in the onset of headaches.

Lethargy or confusion

While cytokines are vital in fighting off viral infections like Colorado tick fever, they can also affect the brain. This can lead to changes in the brain’s neurotransmitters, which can cause significant fatigue and confusion.

Nausea, vomiting, and abdominal pain

Cytokines can stimulate a part of the brain called the medulla oblongata. This area can trigger nausea and vomiting, which is often accompanied by abdominal pain.


Colorado tick fever may cause a flat or pimply rash on the skin. The white blood cells that are activated when the immune system attempts to fight off the virus may cause inflammation and skin irritation, leading to a rash.

The location and appearance of the rash can vary depending on the individual.

Light sensitivity

Although this is a less common symptom, some people may experience sensitivity to light due to the virus’s effect on the meninges, the protective covering of the brain and spinal cord.

When the meninges become inflamed, it can increase eye sensitivity, leading to discomfort in bright light.

Skin pain

The release of cytokines into the body can cause inflammation of the skin and nearby tissues, which can lead to sensitivity and pain in the skin.

If you have a rash or skin lesions as a result of this condition, this may also cause skin pain.


As fever is a common symptom of Colorado tick fever, you may also experience some sweating due to the increase in your body temperature.

Is Colorado Tick Fever Contagious?

As mentioned above, CTF develops as a result of a tick bite. This is the most common cause of the virus. According to the CDC, the virus is not transmitted from person to person.

Diagnosing Colorado Tick Fever

A healthcare professional will conduct a thorough physical examination and ask you about your symptoms to determine if you have CTF. They’ll also inquire about your recent outdoor activity.

Your doctor might run a complete blood count (CBC) and liver function test to confirm if you have Colorado tick fever.

These tests confirm the infection by determining if the CTF antibody is present in your body.

Treatments for Colorado Tick Fever

If you develop any of the symptoms outlined above, seek medical treatment because CTF can lead to complications such as:

  • Meningitis: Inflammation in the membranes in the spinal cord and brain.

  • Encephalitis: Inflammation of the brain tissue.

  • Repeated bleeding episodes: These occur with no apparent cause.

  • Hemorrhagic fever: Damage to the blood vessels and some organs.

Your symptoms can also lead to other health conditions like dehydration due to vomiting. A healthcare provider can help to treat the unpleasant and painful symptoms associated with CTF.

In severe cases, you may be hospitalized to receive intravenous (IV) fluids and medications to alleviate pain and fever.

How to Prevent Colorado Tick Fever

The best way to avoid a tick bite is to not visit tick-infested areas, especially in warmer weather.

If you’ll be walking or hiking in tick-infected areas, ensure that you:

  • Wear closed shoes so that ticks can’t attach to your feet

  • Wear long sleeves to protect your upper body from ticks

  • Walk in the center of trails to avoid contact with bush and grass where ticks may be

  • Apply tick repellents directly to your skin or clothing

  • Tuck long pants into your socks to protect your legs

  • Wear light-colored clothing, as this makes ticks more visible. This means you can see and remove them more easily.

  • Check your body thoroughly for ticks after outdoor activities. Ticks are typically found on the thighs, arms, underarms, and legs.

  • Keep an eye on your pets for ticks

Key Point: What to Do If You Find a Tick

If you find a tick on yourself or a pet, use a pair of fine-tipped tweezers to grab the tick as close to the surface of the skin as possible.

The CDC advises against removing the tick with your fingers, as this may leave parts of it behind in the skin. Pull the tweezers upward and refrain from twisting or jerking the tick.

Once the tick has been removed, thoroughly clean the area of the bite with rubbing alcohol or soap and water.

The tick should be disposed of by placing it in alcohol, a sealed bag or container, or by flushing it down the toilet.

Wear gloves or use tissues to protect your hands while removing a tick. After tick removal, ensure that you wash your hands thoroughly with soap and water.

Donating Blood after Colorado Tick Fever

According to the CDC, people who have had Colorado tick fever shouldn’t donate blood or bone marrow for at least six months following recovery from this condition.

This is because the virus can remain in the red blood cells for several months after the tick bite and be passed to others through a blood transfusion or bone marrow transplant.

Where Can I Learn More About Colorado Tick Fever?

While LifeMD offers care to patients with certain viral infections, Colorado tick fever is a serious condition that requires ongoing specialty care from an in-person healthcare provider.

However, we may be able to help you manage the symptoms of CTF with medication and professional advice.

Make an online appointment to consult with a board-certified physician or nurse practitioner.

LifeMD makes it easy to stay on top of your health because talking to a doctor, filling your prescriptions, getting your labs done—and more—are all easy and cost-effective. Come discover a healthcare solution built around you and your life.

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This article is intended for informational purposes only and should not be considered medical advice. Consult a healthcare professional or call a doctor in the case of a medical emergency.

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