medical Definition of Ehrlichia
:a genus of gram-negative nonmotile bacteria that are transmitted chiefly by tick bites and are intracellular parasites of humans and animals infecting the cytoplasm especially of circulating white blood cells (such as monocytes and granulocytes)
Note:
Certain members of the genus Ehrlichia (such as E. equi and E. phagocytophila) are now typically placed in the genus Anaplasma.
— see ehrlichiosis 
