“Orange” You Glad You Checked the Buffy Coat?

The incidence of tick-borne human infectious syndromes has dramatically risen in the last 2 decades, leading to significant morbidity and mortality. The importance of a rapid and accurate diagnosis to distinguish anaplasmosis from other febrile illnesses is paramount for the prompt administration of appropriate antibiotics and is imperative for the successful treatment of the tick-borne infections. We summarize the current literature describing the biology, clinical presentation, and epidemiology of human granulocytic anaplasmosis. In addition, we report a case of human granulocytic anaplasmosis in one of the less common geographical areas (Pennsylvania) during the winter month of December. Laboratory methods, including use of an acridine orange buffy coat fluorescent stain that helped decreased the time to result and increased confidence in the diagnosis, are also described.