[4] Human monocytic ehrlichiosis caused by E. chaffeensis is known to spread through tick infection primarily in the Southern, South-central and Mid-Atlantic regions of the United States.

[5] In recent years, the lone star tick has expanded its range along the East Coast to New England, putting more humans at risk for tick-borne infections.

[6] It is named for Fort Chaffee, where the bacterium was first discovered in blood samples of infected patients.

The white-tailed deer (Odocoileus virginianus) is known to be the main competent reservoir for E. chaffeensis[1] and the lone star tick (Amblyomma americanum) is the principal vector for human transmission.

[1] Doxycycline treatment is suggested for any patients presenting symptoms of an Ehrlichia infection during the appropriate season and potential tick exposure.