Ehrlichiosis is a rickettsial disease of animals and humans caused by vario
us species of Ehrlichia. These obligate intracellular microorganisms infect
granulocytes or monocytes of mammalian hosts and are transmitted mostly by
ticks. The febrile disease is often undiagnosed and characterized by leuko
penia, anemia and thrombocytopenia. The diagnosis of ehrlichiosis is based
on clinical findings, tick infestation, direct or indirect detection of the
agent, and serology. The role of native and imported ehrlichiae of animals
in Switzerland is discussed.