Anaplasma phagocytophilum (formerly Ehrlichia phagocytophilum) is a gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis. Anaplasma phagocytophilum is a Gram-negative, ...