A previously unknown species of the tick-borne Ehrlichia
bacterium was responsible for mysterious infections affecting
four people in Wisconsin and Minnesota in 2009, researchers
reported in the Aug. 4 issue of the New England Journal of
Medicine. Culturing, serological testing, and DNA analysis
confirmed that the four individuals, all of whom recovered, were
infected with a still unnamed Ehrlichia species distinct from E.
chaffeensis and E. ewingii, the most common pathogens
responsible for ehrlichiosis in the U.S., according to Dr. Bobbi
S. Pritt of the Mayo Clinic in Rochester, Minn. and colleagues.
Currently designated as Ehrlichia Wisconsin HM543746, the new
species appears most closely related to E. muris, which until
recently was thought to be confined to eastern Europe and parts
of Asia. Pritt and colleagues found the two species to be 98
percent genetically similar. Read this story on
www.medpagetoday.com. However, another research group recently
reported that E. muris, or a very similar bacterium, w