Transfusion transmission of parasites and prions

Blood recipients in the United States face low risk for transfusion of a component contaminated with parasites. This chapter discusses parasitic and prion agents potentially found in blood donors, associated risks, and strategies for mitigating these risks. Concern for transfusion-transmitted babesiosis recently culminated in regulatory guidance in the US after years of documenting expanded transmission and refined estimates of transfusion risk. Public health authorities have achieved considerable success in reducing risk and morbidity from Chagas disease. Once endemic throughout much of its territory, malaria in the US is almost exclusively due to imported infections. Leishmania species are protozoan parasites with broad distribution worldwide. Toxoplasmosis is often severe in immunocompromised hosts, and it is a common opportunistic infection of persons with AIDS. Prions can be transmitted through several routes of infection, which determine the length of the silent incubation period in an infected host.