Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ Key Features ++ Tick-borne gram-negative obligate intracellular bacteria Two main clinical entities Human granulocytic ehrlichiosis (typically Anaplasma phagocytophilium and, rarely, Ehrlichia ewingii) Human monocytic ehrlichiosis (typically Ehrlichia chaffeensis) Bacteria form morulae, intracytoplasmic aggregates within leukocytes In the United States, mainly found in mid-Atlantic, southeastern, and central states Rare serious sequelae include acute respiratory failure and acute respiratory distress syndrome; neurologic complications, the most common being meningoencephalitis and aseptic meningitis; acute kidney disease (which may mimic thrombotic thrombocytopenic purpura); hemophagocytic syndrome, and multi-organ failure May see coinfection with other tick-borne illnesses (eg, Lyme disease or babesiosis) ++ Clinical Findings ++ Clinical disease of human monocytic ehrlichiosis ranges from mild to life threatening Incubation period is 1–2 weeks Prodrome of malaise, rigors, and nausea, followed by fever, and headache Respiratory failure, acute kidney disease, and encephalopathy may ensue in severe cases ++ Diagnosis ++ Leukopenia, absolute lymphopenia, thrombocytopenia, and transaminitis common Thrombocytopenia occurs more often than leukopenia in human granulocytic ehrlichiosis Examination of peripheral blood with Giemsa stain may reveal characteristic intraleukocytic vacuoles (morulae) in up to 20% of patients Polymerase chain reaction assay is most sensitive in the first week of illness and can be used as a confirmatory test Indirect fluorescent antibody assay available from the CDC and requires acute and convalescent sera ++ Treatment ++ Treatment for all forms of ehrlichiosis is with doxycycline, 100 mg twice daily (orally or intravenously) for 10–14 days or until 3 days of defervescence Rifampin is an alternative in pregnant women GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessMedicine 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessMedicine Full Site: One-Year Individual Subscription $995 USD Buy Now View All Subscription Options