Transfusion-transmitted babesiosis in an immunocompromised patient: a case report and review.

Babesiosis is a tick- and transfusion-borne disease caused by intraerythrocytic Babesia parasites. In 2009, a 61-year-old Minnesota woman with chronic lymphocytic leukemia and a history of recent chemotherapy and numerous blood transfusions for gastrointestinal bleeding became febrile and anemic 12 days postsplenectomy. Babesia were visualized on blood smears, confirmed by polymerase chain reaction as B. microti. She developed respiratory failure despite initiation of clindamycin and quinine, and required 12 weeks of azithromycin and atovaquone before blood smear and polymerase chain reaction findings were negative. Serologic evidence of B. microti infection was identified in 1 associated blood donor and 1 other recipient of that donor's blood. Babesia infection can be asymptomatic or cause mild to fulminant disease resulting in multiorgan failure or death. Patients with advanced age, asplenia, or other immune compromise are at risk for severe babesiosis and may require prolonged treatment to eradicate parasitemia. Incidence of transfusion-transmitted babesiosis has increased over the past decade.