Ehrlichiosis — In Pursuit of an Emerging Infection

Abstract

Ehrlichia are obligate intracellular coccobacilli resembling rickettsia that have historically been associated with diseases of animals. The etiologic agent of the hemorrhagic illness canine ehrlichiosis, Ehrlichia canis, was first recognized in 1935, and other ehrlichia species, which infect horses and ruminants, have since been discovered.The first human ehrlichial infection to be recognized was Sennetsu fever, a mononucleosis-like illness described in Japan in 1954. The first report of ehrlichial infection in the United States was in 1986: a man acquired the infection from a tick bite while traveling in Arkansas.1 Because the patient had an increase in antibodies to E. . . .