A new case report published in Transfusion describes a patient with sickle cell disease (SCD), who had been on a red cell exchange regimen since his youth, with transfusion-transmitted babesiosis (TTB).

The study noted that despite regional screening programs, TTB is still possible and greater vigilance is warranted given the increased vulnerability of patients with SCD undergoing transfusion therapy.

“Babesia was previously regarded as a leading infectious risk to the US blood supply: over 250 cases of transfusion-transmitted babesiosis (TTB) had been reported, almost all (98%) of which implicated [Babesia] microti,” the authors wrote. “The US Food and Drug Administration (FDA) recommendations pertaining to donor screening for Babesia have been successful in reducing the number of TTB in endemic areas.”

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The patient was a man aged 30 years with SCD and cerebrovascular disease who, since his youth, had been on an automated red blood cell (RBC) exchange (RCE) regimen of approximately 10 units every 3 or 4 weeks. He presented to an emergency department with flu-like symptoms, but testing revealed nothing specific and he was discharged.

When his symptoms persisted, further testing revealed intra-erythrocytic inclusions and B microti IgM and DNA. He was treated with azithromycin 500 mg once, followed by 250 mg azithromycin daily for 10 days combined with atovaquone 750 mg twice a day for 10 days. The symptoms resolved.

Given that the patient lived in a state that was endemic for B microti but he had no risk factors for tickborne acquisition, an investigation was initiated with his blood supplier. A total of 58 of the 65 units of RBCs transfused had been screened for B microti. The donors of the remaining 7 units were tested and one was positive for B microti antibodies, although the donor was asymptomatic.

The authors note that this case highlights the importance of increased vigilance among clinicians to the possibility of TTB in patients with SCD, particularly in nonendemic areas where it might be overlooked.  


Costa V, Mercure-Corriveau N, Gourneau J, et al. Transfusion-transmitted babesiosis in a patient with sickle cell disease undergoing chronic red cell exchange. Transfusion. Published online January 13, 2023. doi.10.1111/trf.17244