Although the blood smear was very revealing in this case, it is not specific (Ehrlichia spp. can produce morulae, mainly in monocytes but occasionally in neutrophils), nor are they always seen. Generally, the characteristic morulae in neutrophils are mostly seen only in the earlier stages of the disease.
Typical CBC findings include leukopenia with a relatively lower lymphocyte count than neutrophil count, thrombocytopenia, and, in some cases, anemia. Chemistry tests include moderately elevated liver enzymes, AST, and ALT.
Typical symptoms, together with leukopenia and thrombocytopenia, should prompt specific testing for A. phagocytophilum, even in the absence of observed morulae, especially if the patient's history includes a tick bite.
