Ehrlichiosis masquerading as thrombotic thrombocytopenic purpura

Ehrlichiosis is a rare tickborne illness that can manifest from an asymptomatic, self-limiting disease to a severe presentation with encephalopathy and renal failure. Ehrlichiosis is diagnosed largely based on patient history with confirmatory tests including peripheral blood smear, serology and PCR. Empiric treatment is warranted in patients with suspected tick bites as a delay in treatment can result in multiorgan failure. We discuss a case of ehrlichiosis that presented with the classic pentad of thrombotic thrombocytopenic purpura (TTP). A history of a tick bite was elicited and intravenous doxycycline 100 mg two times a day was initiated. Tick panel results revealed a positive Ehrlichia chaffeensis IgG and IgM titres, consistent with human monocytic ehrlichiosis. Autoimmune workup and antibodies to Borreliaburgdorferi were negative, and ADAMTS13 activity assay results were inconsistent with TTP. The patient completed 14 days of intravenous doxycycline and had an uneventful recovery.