In 2009, a new species of Ehrlichia was detected in four human patients (3 from Wisconsin, 1 from Minnesota) using molecular laboratory testing techniques. This new bacterial species was found to be most closely related to Ehrlichia muris. This newly identified species has been called Ehrlichia muris-like (EML) and will likely be renamed as a subspecies called Ehrlichia muris eauclairensis.
For further information we refer you to:
The Univeristy of Wisconsin’s Department of Entomology website
See also: this article in the New England Journal of Medicine