A tick-borne febrile illness most commonly characterized by acute onset, accompanied by headache, myalgia, rigors and/or malaise. Clinical laboratory findings may include intracytoplasmic microcolonies (morulae) in leukocytes of peripheral smear, cerebrospinal fluid (CSF), or bone marrow aspirate or biopsy, cytopenias (especially thrombocytopenia and leukopenia), and elevated liver enzymes (especially alanine aminotransferase or aspartate aminotransferase). There are two clinically similar yet serologically distinct forms of ehrlichiosis: a) human granulocytic ehrlichosis (HGE), caused by infection with an Ehrlichia equi-like agent and found primarily in the upper midwest and northeast, and b) human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis infection and found primarily in the southeastern quadrant of the United States.
A clinically compatible case with either a single IFA serologic titer greater than or equal to 64 or intracytoplasmic morulae identified in blood, bone marrow, or CSF leukocytes
A clinically compatible case that is laboratory confirmed
All laboratory testing should be conducted by experienced personnel with appropriate training and should include appropriate controls and reagents necessary for accurate etiologic diagnosis. States in which cases of HGE and/or HME have occurred may submit reports to CDC