Screening for Babesia microti in the U.S. Blood Supply

Babesia microti is a leading cause of blood transfusion–associated infection in the United States. Investigators from the American Red Cross present data establishing a potential donor-screening test approach to decrease this risk. Babesia microti is an intraerythrocytic parasite that causes babesiosis. 1 The severity of babesia infection ranges from asymptomatic, most commonly in healthy persons, to fatal, most frequently in persons older than 50 years of age, those who have no spleen (or no functional spleen), and those who are immunocompromised. 2 In the United States, B. microti is transmitted to humans primarily by means of the bite of Ixodes scapularis (also called the deer tick). 3 Babesiosis became a nationally notifiable disease (as defined by the Centers for Disease Control and Prevention [CDC]) in 2011 and was reportable (i.e., reportable to the state, which . . .