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. 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 with 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

Between 2004 and 2015, fewer than three cases of ehrlichiosis a year were reported to the Health Department. Most reported cases were in adults between the ages of 45 of 69. Almost 25% of reported cases were hospitalized for their illness.

The geographic range of the tick that transmits Ehrlichia in the eastern U.S., the lone star tick, extends only slightly into the southern portion of Vermont. Therefore this tick is not commonly found in the state. Residents in the southern areas of Vermont, such as Bennington and Rutland counties, may be more likely to encounter lone star ticks than residents in more northern parts of the state.

While fewer than 30 cases of ehrlichiosis have been reported to the Health Department, more than half of those cases were in Bennington and Rutland county residents.

Preventing Ehrlichiosis

The best way to prevent ehrlichiosis is to prevent tick bites

For more information on ehrlichiosis, visit the CDC Website