Evaluating the prevalence of Hepatitis E virus infection in a large cohort of European blood donors, 2015-2018.

Hepatitis E virus (HEV) is endemic in Europe. However, standardized methods for the surveillance of HEV viremia in the general population are lacking. This study aimed to compare the incidence of HEV among blood donors in two European countries, Germany and Portugal, during the period 2015-2018. The seasonal distribution of HEV infection, as well as host risk factors including age, sex, and blood group phenotype were explored. A total of 191,236 donations from Germany and Portugal were tested for HEV RNA in plasma mini-pools of up to 96 donations using an internally controlled reverse transcription real-time PCR (RT-PCR) assay. The 95% cut-off of the assay was 15 International Units (IU)/mL (CI 10-35 IU/mL) as determined by dilution of the WHO International Standard for HEV RNA. Blood type was determined by agglutination and pattern recognition using the Beckmann Coulter PK 7300 AB0- and Rhesus-Assay. The overall positivity rate was 0.09% with significantly more infections observed in the German cohort (p < 0.0001). Infections peaked in the summer months, and investigation of risk factors revealed that incidence was significantly higher amongst males (p = 0.0002), but was not associated with ABO or Rh(D) blood group phenotypes. No significant relationships between risk factors and viral load were observed. Our findings confirm that HEV infections are highly prevalent in Europe, even amongst otherwise healthy blood donors. Increasing awareness of the seasonal spread and risk factors for HEV transmission is of great importance for individuals susceptible to more severe forms of the disease, such as immunocompromised patients.