Babesia: A Rare Cause of Posttransfusion Hemolytic Anemia

Kathman D, Nesanelis D, Fitzgibbons C. Chest,

2013 Oct 1; 144 (4_MeetingAbstracts): 197A.
*SESSION TITLE:* Infectious Disease Cases II
*SESSION TYPE:* Affiliate Case Report Slide
*PRESENTED ON:* Sunday, October 27, 2013 at 01:15 PM – 02:45 PM
*INTRODUCTION:* We report a case of post-transfusion Babesia infection masquerading as autoimmune hemolytic anemia.
*CASE PRESENTATION:* A 69-year-old female underwent a left knee replacement, with post-operative course complicated by anemia requiring packed red cell transfusion. One month later she developed high fevers and worsening anemia. Workup demonstrated hemolysis with a positive direct Coombs test, suggesting autoimmune hemolytic anemia. She was treated with daily prednisone, followed by rituximab. Two weeks later she presented to our institution for a second opinion and was admitted to the ICU with a hemoglobin of 5 g/dL and platelets of 61 th/mm3. Peripheral smear showed inclusion bodies and 13% parasitemia. Babesia PCR was positive and workup for concomitant tick-borne illnesses was negative. The patient stabilized with packed red blood cell transfusions, clindamycin and quinine, and discontinuation of prednisone and rituximab. Due to persistent anemia and parasitemia, therapeutic apheresis was initiated with success. There was no clinical history of tick exposure, suggesting transmission from the initial blood transfusion, accelerated by immunosuppression.
*DISCUSSION:* Symptoms of babesiosis range from asymptomatic infection to fulminant disease and death, though immunocompetent patients typically experience flu-like symptoms. Most commonly transmitted via the bite of the Ixodes scapularis tick, babesial infection has also been reported after blood transfusion. There is no FDA-approved Babesia screening assay of blood products, and donors may be asymptomatic, despite low-level parasitemia. A retrospective review of the CDC database from 1979-2009, uncovered 162 transfusion-associated cases, mostly in endemic states. The diagnosis should be considered in patients with hemolytic anemia and/or thrombocytopenia, often with fever, and recent exposure to blood products. Giemsa stain may identify intra-erythrocytic ring forms, or the pathognomonic “Maltese cross” on thin blood smear, though PCR is more sensitive. While typically thought of as a nonimmune hemolytic anemia, there are case reports of patients with babesiosis and a positive DAT, though the mechanism is unclear. Treatment with clindamycin and quinine or azithromycin and atovaquone for 7-10 days is recommended in symptomatic patients, though more critically-ill or immunosuppressed patients may require 3-18 months of treatment. Exchange transfusion may be potentially life-saving in patients with significant parasitemia, severe hemolysis, and renal or pulmonary compromise.
*CONCLUSIONS:* Accurate identification of post-transfusion hemolytic anemia from Babesia infection is necessary to ensure appropriate and timely treatment.

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