Babesiosis Transmitted by a Transfusion of Frozen-Thawed Blood

BABESIOSIS in the United States is caused by Babesia mi-croti, a hemosporozoan parasite of wild rodents that is transmitted to humans by the tick, Ixodes dammini (1). Almost 100 clinical and subclinical cases of babesiosis have been reported from the coastal areas and off-shore islands of Long Island, New York and Massachusetts (2). We report the first case of infection due to Babesia microti in a splenectomized woman after transfusion with frozen-thawed erythrocytes (deglycerolized, washed) from a seropositive donor. This patient is the youngest asplenic person and the only person with thalassemia ma-jor to have had a documented case of babesiosis. A 23-year-old splenectomized woman with transfusion-dependent thalassemia major was admitted to New York Hos-pital on 26 June 1980 with a 10-day history of recurrent fevers