Ehrlichiosis and anaplasmosis are two closely related tickborne diseases, caused by different germs. Although both diseases concentrate east of the Rocky Mountains, they usually occur in different areas. Ehrlichiosis, or human monocytic ehrlichiosis (HME), is found mainly in the mid-Atlantic, southeastern, and south central states. Anaplasmosis (formerly called human granulocytic ehrlichiosis, or HGE) occurs more often in the Northeast and upper Midwest.
Ehrlichiosis and anaplasmosis are emerging infectious diseases in the United States and other countries. (Emerging infectious diseases are diseases first described by researchers within the last two decades.) In 2010, 1,761 cases of anaplasmosis and 740 cases of ehrlichiosis were reported to the Centers for Disease Control and Prevention. Very few cases of ehrlichiosis and no cases of anaplasmosis were reported from states west of the Continental Divide. Ticks carrying the anaplasmosis bacterium have been collected, however, along the West Coast and in some southwestern states.
Last Updated September 12, 2013
Last Reviewed September 12, 2013