All types of human ehrlichioses and anaplasmosis are nationally notifiable diseases.
Seasonality is due to higher likelihood of tick exposure/bite when people spend more time outdoors in warmer months.
Presumptive diagnosis is made in patients with potential tick exposure/demonstrated tick bite combined with fever and other characteristic constitutional symptoms plus leukopenia and/or thrombocytopenia and elevated LFTs. Serology or polymerase chain reaction confirms diagnosis.
Treatment with antibiotics should be started immediately if the diagnosis is suspected clinically. Doxycycline is the drug of choice.
Tick-borne emerging infections of white blood cells that are most commonly caused by 3 different gram-negative bacteria from the Anaplasmataceae family: Ehrlichia ewingii, E chaffeensis, and Anaplasma phagocytophilum. Ehrlichia muriseauclairensis (formerly known as Ehrlichia muris-like agent, EMLA) also causes symptomatic infection and is the most recently recognized form of human ehrlichiosis. The type of infection that develops depends on the infecting bacteria and includes human monocytotropic/monocytic ehrlichiosis (HME), human granulocytotropic/granulocytic anaplasmosis (HGA), and human ewingii ehrlichiosis (HEE). The clinical manifestations of each type are generally the same. This topic deals with human infection only. CDC: ehrlichiosis external link opens in a new window CDC: anaplasmosis external link opens in a new window
History and exam
Juan P. Olano, MD
Department of Pathology
University of Texas Medical Branch
JPO is the author of a number of references cited in this topic.
Linda S. Nield, MD
Associate Professor of Pediatrics
West Virginia University School Of Medicine
LSN declares that she has no competing interests.
Richard Reithinger, MD, PhD
London School of Hygiene and Tropical Medicine
RR declares that he has no competing interests.
CDC health information for international travel: rickettsial diseases (including spotted fever & typhus fever, rickettsioses, scrub typhus, anaplasmosis, and ehrlichiosis) external link opens in a new windowMore guidelines
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