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Ehrlichiosis: Wisconsin Data

The number of reported cases of ehrlichiosis has been increasing in Wisconsin.

In 2020, Wisconsin had 17 probable and confirmed cases of ehrlichiosis.

Several species of Ehrlichia bacteria cause ehrlichiosis. In Wisconsin, species of Ehrlichia that can cause illness include:

  • Ehrlichia chaffeensis
  • Ehrlichia muris eauclairensis
  • Ehrlichia ewingii

Ehrlichiosis is preventable and treatable. Learn more about Tick Bite Prevention.

Read about Signs and Symptoms from the CDC (Centers for Disease Control and Prevention).

The graphs below show statewide data for ehrlichiosis.

For national data, visit the CDC webpage on Ehrlichiosis Epidemiology and Statistics.

Map of Ehrlichiosis cases by county

Ehrlichiosis data

In the past, ehrlichiosis surveillance included human granulocytic ehrlichiosis and human monocytic ehrlichiosis. As of 2008, the surveillance case definition changed to classify the disease by two different bacterial infections: Anaplasma phagocytophilum and Ehrlichia species.

Ehrlichiosis cases in Wisconsin

Three species of Ehrlichia cause illness in Wisconsin and other parts of the United States: E. chaffeensis, E. muris eauclairensis, and E. ewingii.

Ehrlichiosis, E. chaffeensis cases in Wisconsin

E. muris eauclairensis is a newer species of Ehrlichia. It was discovered in Wisconsin and Minnesota in 2009.

Total cases of Ehrlichiosis, E. muris eauclairensis

E. ewingii is rare in Wisconsin. There have been two reported cases in the state.

Ehrlichiosis, E. ewingii total cases

Ehrlichiosis cases reported by month and age

Average ehrlichiosis cases by month

Average ehrlichiosis cases by age

Learn more about ehrlichiosis

Contact us

Questions about illnesses spread by ticks? We’re here to help.

Bureau of Communicable Diseases
Phone: 608-267-9003
Fax: 608-261-4976

Last revised April 10, 2023