Trends in Microbiology

Ehrlichia chaffeensis is an obligatory intracellular Gram-negative bacterium that causes human monocytic ehrlichiosis (HME), a tick-borne infection with a spectrum of severity from mild to severe and increasing public health relevance. While initially identified as a human pathogen, E. chaffeensis infections have been confirmed naturally in humans and dogs. The pathogen is primarily transmitted by the three-host lone star tick, Amblyomma americanum, and persists in white-tailed deer (Odocoileus virginianus) as its principal reservoir.