Transfusion-transmitted Babesia spp.: a changing landscape of epidemiology, regulation, and risk mitigation

Document Type

Journal Article

Publication Date



Journal of clinical microbiology








Babesia; clinical diseases; risk mitigation; transfusion transmission; vectors


spp. are tick-borne parasites with a global distribution and diversity of vertebrate hosts. Over the next several decades, climate change is expected to impact humans, vectors, and vertebrate hosts and change the epidemiology of . Although humans are dead-end hosts for tick-transmitted , human-to-human transmission of spp. from transfusion of red blood cells and whole blood-derived platelet concentrates has been reported. In most patients, transfusion-transmitted (TTB) results in a moderate-to-severe illness. Currently, in North America, most cases of TTB have been described in the United States. TTB cases outside North America are rare, but case numbers may change over time with increased recognition of babesiosis and as the epidemiology of is impacted by climate change. Therefore, TTB is a concern of microbiologists working in blood operator settings, as well as in clinical settings where transfusion occurs. Microbiologists play an important role in deploying blood donor screening assays in endemic regions, identifying changing risks for in non-endemic areas, investigating recipients of blood products for TTB, and drafting TTB policies and guidelines. In this review, we provide an overview of the clinical presentation and epidemiology of TTB. We identify approaches and technologies to reduce the risk of collecting blood products from -infected donors and describe how investigations of TTB are undertaken. We also describe how microbiologists in non-endemic regions can assess for changing risks of TTB and decide when to focus on laboratory-test-based approaches or pathogen reduction to reduce TTB risk.


Microbiology, Immunology, and Tropical Medicine