Ehrlichiosis is a disease caused by an infection with one of several species of Ehrlichia bacteria. In the eastern United States, ehrlichiosis is typically caused by either Ehrlichia chaffensis or Ehrlichia ewingii. Both of these bacteria are transmitted by the bite of the lone star tick, Amblyomma americanum. This tick species is not considered to be established in Vermont. Ehrlichiosis may also be transmitted through blood transfusions.


Symptoms of ehrlichiosis usually begin one to two weeks after being bitten by an infected tick. Symptoms include fever, headache, chills, malaise, muscle pain, confusion, red eyes, nausea, vomiting and diarrhea. A skin rash is not a common symptom of ehrlichiosis, but some people infected with Ehrlichia may develop one. The rash is more common in children with the disease than in adults.  

Ehrlichiosis is a serious disease that can be fatal if not treated appropriately. While anyone can get ehrlichiosis, people with compromised immune systems are at a greater risk for severe disease and death.

The symptoms of ehrlichiosis can be non-specific and vary from person to person, making diagnosis difficult. Because treatment with antibiotics is more effective when started earlier in the illness, a prompt diagnosis based upon clinical signs and symptoms can be important. Blood collected at the time of diagnosis can then be used to confirm the diagnosis.

Ehrlichiosis in Vermont

Since 2005 there have only been eight confirmed cases of ehrlichiosis reported to the Health Department.

The lone star tick, Amblyomma americanum, is the tick primarily responsible for transmitting Ehrlichia in the U.S. The geographic range of the lone star tick has been spreading northward. Presence of a single life stage of the tick has been documented in Vermont, but this species of tick is not considered established, or able to complete its lifecycle, in Vermont.

Preventing Ehrlichiosis

The best way to prevent ehrlichiosis is to prevent tick bites. 

Learn how to Be Tick Smart.

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