Ehrlichiosis — Ticks, Dogs, and Doxycycline

Abstract

The ehrlichia are obligate intracellular bacteria that infect a variety of animals, usually with ticks as vectors. Ehrlichia sennetsu, the first species recognized to infect humans, causes a mononucleosis-like illness that so far has been seen only in Asia.1 In 1987, the first case of human ehrlichiosis in the United States was reported. Because of serologic cross-reaction, the infection was thought to be caused by an agent of ehrlichiosis in dogs, E. canis. 2 The organism was subsequently isolated in cell culture, was shown to be distinct from E. canis, and was named E. chaffeensis. 3 Because the organism often forms characteristic . . .