Abstract
The risk and importance of transfusion-transmitted hepatitis E virus (TT-HEV) infections by contaminated blood products is currently a controversial discussed topic in transfusion medicine. The infectious dose, in particular, remains an unknown quantity. In the present study, we illuminate and review this aspect seen from the viewpoint of a blood donation service with more than 2 years of experience in routine HEV blood donor screening. We systematically review the actual status of presently known cases of TT-HEV infections and available routine NAT-screening assays. The review of the literature revealed a significant variation regarding the infectious dose causing hepatitis E. We also present the outcome of six cases confronted with HEV-contaminated blood products, identified by routine HEV RNA screening of minipools using the highly sensitive RealStar HEV RT-PCR Kit (95% LOD: 4.7 IU/mL). Finally, the distribution of viral RNA in different blood components [plasma, red blood cell concentrate (RBC), platelet concentrates (PC)] was quantified using the first WHO international standard for HEV RNA for NAT-based assays. None of the six patients receiving an HEV-contaminated blood product from five different donors (donor 1: RBC, donor 2–5: APC) developed an acute hepatitis E infection, most likely due to low viral load in donor plasma (<100 IU/mL). Of note, the distribution of viral RNA in blood components depends on the plasma content of the component; nonetheless, HEV RNA could be detected in RBCs even when low viral plasma loads of 100–1,000 IU/mL are present. Comprehensive retrospective studies of TT-HEV infection offered further insights into the infectivity of HEV RNA-positive blood products. Minipool HEV NAT screening (96 samples) of blood donations should be adequate as a routine screening assay to identify high viremic donors and will cover at least a large part of viremic phases.
Highlights
Hepatitis E virus (HEV) is an emerging infectious threat to blood safety
The analysis led to the conclusion that the prevention of HEV transmission through the screening of blood donations is not markedly expensive compared with other blood-screening measures
We further describe six new cases of patients transfused with HEV-contaminated blood products, and none of the recipients developed HEV infection
Summary
Hepatitis E virus (HEV) is an emerging infectious threat to blood safety. In the recent decade, there have been several reports of transfusion-transmitted hepatitis E virus (TT-HEV) infection [for review, see Ref. [1]], the risk of infection through consumption of raw or undercooked pork and wild boar is even greater [2]. The German Advisory Committee on Blood (Arbeitskreis Blut) recommended a NAT sensitivity of 100 IU HEV RNA/mL [per single donation [12]], which is difficult to achieve with the currently available NAT assays using minipool NAT. For these reasons, the ongoing discussions address the question of the most appropriate and effective strategy to minimize the risk of TT-HEV infection, taking into account the costs, the logistics of testing, and the infection risk and outcome of HEV-infected blood recipients. The present review provides a comprehensive view of the various aspects of TT-HEV infection and a discussion on the current status on the issue of screening for this virus
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