Case report: Polymerase chain reaction testing of tick bite site samples for the diagnosis of human granulocytic anaplasmosis

Abstract

Human granulocytic anaplasmosis (HGA) is a tick-borne infectious disease caused by Anaplasma phagocytophilum, an obligate intracellular bacterium. Until now, the utility of tick-bite site samples for HGA diagnosis has not been reported. Using a patient's buffy coat and tick-bite site crust samples, we performed polymerase chain reaction (PCR) testing using Ehrlichia- or Anaplasma-specific primers. PCR with buffy coat and crust samples obtained before doxycycline administration was positive. Six days after doxycycline administration, PCR with the buffy coat samplewas negative butPCRwith a crust tissue sample from the tick-bite site remained positive. This is the first case to suggest that crust tissue at the tick-bite site may be useful for early HGA diagnosis in patients who have already been treated with antibiotics such as doxycycline.