(109) Ticking Me Off: A Case of Sepsis due to Anaplasmosis With Underlying Cold Agglutinin Disease

Introduction: Human granulocytic anaplasmosis (HGA) is caused by the bacterium Anaplasma phagocytophilum, typically transmitted by Ixodes scapularis. This tickborne disease is endemic to the Northeastern United States. Patients have nonspecific symptoms such as headache and fever, making it difficult to recognize. Direct bites or rashes are often not present. Laboratory findings such as anemia, lymphopenia, and direct visualization of morulae in granulocytes on blood smear are the hallmarks of this disease. This patient had an atypical presentation of HGA that was only discovered during an anemia workup.

Description: An 80-year-old female presented with vomiting, jaundice, and a fever of 40.1C. Labs included hemoglobin (Hgb) of 6.5, lymphocytopenia, and elevated liver function tests (LFTs). Imaging of the abdomen showed evidence of cholelithiasis with mild pericholecystic fat stranding, but hepatobiliary iminodiacetic acid scan was negative for acute cholecystitis. Ascending cholangitis was on the differential, but unlikely without pain. On anemia workup, lactate dehydrogenase (LDH) was elevated and haptoglobin (HP) level was undetectable. A blood smear showed left-shifted neutrophils with intracellular morulae and red cell clumping, consistent with Anaplasmosis infection and Cold agglutinin disease. Doxycycline and prednisone were started. Anaplasma was confirmed by polymerase chain reaction. Cold agglutinin titer returned at 1:20480 and rituximab therapy was initiated. After a prolonged course, she remained hemodynamically stable with a Hgb of 6.0. Although the anemia persisted, there was evidence of recovery with a decrease in LDH and an increase in both HP and reticulocyte count.

Discussion: This case of HGA was misleading. Jaundice with an obstructive pattern on LFTs led us to believe sepsis was due to a hepatobiliary etiology. Her profound anemia and concern for shock in the ICU led to the discovery of both underlying Cold agglutinin disease (CAD) and Anaplasma. It is unclear if HGA led to IgM-mediated autoimmune hemolytic anemia, however without it, infectious treatment may have been delayed. In endemic areas, we must avoid anchoring bias and maintain a high clinical suspicion for HGA in the undifferentiated patient, or risk late identification and untoward outcomes.