Babesiosis and Its Significance in Transfusion Medicine from a European Point of View.

BACKGROUND

Babesiosis, caused by intraerythrocytic parasites of the genus Babesia, represents an emerging global health threat due to its capacity for persistent infection and transfusion transmission. The ability of Babesia spp. to establish chronic, asymptomatic infections lasting up to 2 years in immunocompetent hosts creates a substantial reservoir of infectious blood donors, making transfusion-transmitted babesiosis (TTB) a critical blood safety concern.

SUMMARY: The epidemiology of babesiosis differs markedly between regions, with B. microti predominating in North America and B. divergens in Europe. In the USA, seroprevalence studies among blood donors reveal rates of 0.38% in endemic regions. In 2019, the US Food and Drug Administration (FDA) issued nonbinding recommendations for year-round regional nucleic acid testing of individual donations in 14 endemic states and Washington DC, or alternatively, the use of FDA-approved pathogen reduction technology for blood components [Pathogens. 2021;10(9):1176; Recommendations for reducing the risk of transfusion-transmitted babesiosis, 2019]. TTB can result in severe clinical complications with mortality rates approaching 20%, particularly affecting immunocompromised recipients. European studies demonstrate significantly lower prevalence rates, with minimal Babesia DNA detection in blood donor populations from Austria [Transfus Med Hemother. 2023;50(4):330-3] and Poland [Przegl Epidemiol. 2023;77(2):146-52], despite serological evidence of exposure. Current detection methods include microscopic examination, nucleic acid amplification, antigen detection, and antibody testing, with screening programs proving effective in endemic regions.

KEY MESSAGES: Persistent Babesia infections pose a significant threat to blood safety, necessitating region-specific risk assessment and mitigation strategies. The substantial difference in prevalence between North American and European blood donor populations highlights the importance of tailored approaches to screening implementation. Enhanced surveillance, novel therapeutic strategies, and comprehensive prevention measures - including advanced diagnostics, tick-avoidance programs, and pathogen reduction technologies - are essential for minimizing the global health burden of persistent babesiosis and protecting vulnerable populations from this emerging transfusion-transmitted threat.