Direct Cultivation of the Causative Agent of Human Granulocytic Ehrlichiosis

Ehrlichia are intracellular organisms that may infect a variety of mammalian hosts. 1 The rapid emergence of a new human ehrlichial infection, human granulocytic ehrlichiosis, was recently reported. This infection was first recognized in north central Minnesota and Wisconsin 2 , 3 and has now been reported in New York 4 and Massachusetts. 5 Preliminary studies 4 suggest that human granulocytic ehrlichiosis is transmitted by Ixodes scapularis ticks, also a vector of Lyme disease. Human granulocytic ehrlichiosis is an acute, sometimes fatal, febrile syndrome. Unlike Lyme disease, it is usually accompanied by leukopenia, thrombocytopenia, and elevated serum aminotransferase levels. Little is known about the agent that . . .