Human ehrlichiosis can be caused by several different species. These include Ehrlichia muris eauclairensis (formerly called Ehrlichia muris-like), Ehrlichia chaffeensis, and E. ewingii. Ehrlichia muris eauclairensis is transmitted by the deer tick. This graph is from the Wisconsin Department of Health Services and shows the trend in human cases since 2009. For more information, visit https://www.dhs.wisconsin.gov/tick/ehrlichiosis-about.htm 
