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Ehrlichiosis is an infection passed through a tick bite. It can be treated with medication, but can be fatal if left untreated.


Ehrlichiosis is caused by specific ehrlichia bacteria. The bacteria are passed through the bite of a tick, specifically the lonestar tick, deer tick, and dog tick.

Risk Factors

Spending time in an area where ticks are common, increases your risk of infection. This includes outdoor areas with high grass or bushes. Not all tick bites will lead to infection.

The infection is most often found in the mid-Atlantic, southeastern, and south central United States.

The risk of a severe infection is increased in people with impaired immune systems such as HIV or cancer.


It may take at least 1-2 weeks before symptoms develop. The first symptoms are often flu-like symptoms such as:

  • Fever
  • Chills
  • Muscle and joint aches
  • Nausea and loss of appetite
  • Headaches
  • Fatigue

Some may also develop:

  • Stiff neck
  • Confusion

Some people also develop a rash.

An untreated infection can cause difficulty breathing and bleeding problems.

Headache and Neck Stiffness
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You will be asked about your symptoms and medical history. You may not have known you were bitten. You may not have a bite mark. You may be asked if you have spent time in areas known for ticks. A physical exam will be done.

A blood test may be done to:

  • Confirm the presence of the ehrlichiosis
  • Look for any other infection that may have been passed from the tick
  • Look for any signs of organ damage


Ehrlichiosis can be successfully treated with antibiotics.

Other medications may be advised to help relieve symptoms until the infection has cleared. It may take a few weeks before all of the symptoms have gone away completely.


Avoiding tick bites is the best way to prevent ehrlichiosis. Learn when ticks are most active in your area. Avoid tall grass, woods, and brush during these times. If you are in these areas:

  • Wear light colored clothing to make ticks easier to see.
  • Wear long pants and socks. Consider tucking your pants into your socks so the ticks have a harder time getting to your skin.
  • Use a bug repellent that contains DEET. Follow directions for use on the container.

After being outdoors:

  • Check yourself and your pets thoroughly for ticks.
  • Quickly remove any ticks that you have found.
  • If a tick is attached to the skin, remove it as soon as possible. Grab the tick close to your skin and pull out with steady pressure. Wash the area where the tick was attached with soap and water.

It may take at least 24 hours for the infection to pass through the bite. Not all tick bites will cause an infection. If you were bitten by a tick, watch the area over the next few days. Call your doctor if you develop any symptoms.


Centers for Disease Control and Prevention

Family Doctor—American Academy of Family Physicians

Canadian Resources

Health Canada

Public Health Agency of Canada


Ehrlichiosis. American Academy of Family Physicians website. Available at: Updated February 2014. Accessed September 23, 2014.

Ehrlichiosis. Centers for Disease Control and Prevention website. Available at: Updated July 2017. Accessed September 1, 2017.

Ehrlichiosis and anaplasmosis. EBSCO DynaMed Plus website. Available at: Updated December 9, 2016. Accessed September 1, 2017.