Babesia infection through blood transfusions: reports received by the US Food and Drug Administration, 1997-2007.

BACKGROUND Human babesiosis is an illness with clinical manifestations that range from asymptomatic to fatal. Although babesiosis is not nationally notifiable, the US incidence appears to be increasing. Babesia infection is a transfusion-transmissable disease. An estimated 70 cases were reported during 1979-2007; most of these cases were reported during the past decade. METHODS We queried the 3 following US Food and Drug Administration safety surveillance systems to assess trends in babesiosis reporting since 1997: fatality reports for blood donors and transfusion recipients, the Adverse Event Reporting System (which includes MedWatch), and the Biological Product Deviations Reporting system.We analyzed fatality reports for time frames, clinical presentations, and patient and donor demographic characteristics. RESULTS Eight of 9 deaths due to transfusion-transmitted babesiosis that were reported since 1997 occurred within the past 3 years (2005-2007). Four implicated donors and 5 patients lived in areas where Babesia infection is not endemic. Increasing numbers of Biological Product Deviations Reports were submitted to the US Food and Drug Administration over the past decade; the Adverse Event Reporting System received no reports. CONCLUSIONS After nearly a decade with no reported death due to transfusion-transmitted babesiosis, the US Food and Drug Administration received 8 reports from November 2005 onward. The increased numbers of deaths reported and Biological Product Deviations Reports suggest an increasing incidence of transfusion-transmitted babesiosis. Physicians should consider babesiosis in the differential diagnosis in immunocompromised, febrile patients with a history of recent transfusion, even in areas where Babesia infection is not endemic. Accurate and timely reporting of babesiosis-related donor and transfusion events assists the US Food and Drug Administration in developing appropriate public health-control measures.