Hepatitis E Virus Infection in Swiss Transplant Recipients: Seroprevalence, Incidence, and the Role of Transfused Blood Products.

BACKGROUND: In Switzerland, hepatitis E virus (HEV) Genotype 3 is the leading cause of acute viral hepatitis and is mainly transmitted via contaminated pork, but also through solid organ transplantation and blood transfusion. Immunocompromised patients are particularly at risk, as chronic hepatitis may develop. This nationwide cross-sectional study aimed to retrospectively assess HEV epidemiology in SOT and allogeneic hematopoietic stem cell transplant recipients. METHODS: A total of 2942 patients from the Swiss Transplant Cohort Study sampled at transplantation date (T0) and at 1-year follow-up (T12) were tested for anti-HEV IgG and HEV RNA. For seroconverted or HEV RNA-positive patients, further analyses were performed, including characterization of samples collected 6 months posttransplantation (T6). Furthermore, 587 archived blood donor samples were retrospectively examined to investigate their potential role in HEV transmission. RESULTS: The anti-HEV IgG seroprevalence of 21.6% at T0 and 19.4% at T12 in transplant recipients was comparable to that of Swiss blood donors. However, the overall incidence of HEV RNA of 1:210 was more than 20-fold higher, with 53% of infections persisting for 6 months or more. Except for one imported genotype 1g case, all infections were of Genotype 3, predominantly subtype 3h3, which is endemic in Switzerland. Notably, a transfusion-transmitted HEV infection was identified. CONCLUSION: Given the increased susceptibility of transplant recipients to HEV and their reduced ability to clear the infection, surveillance and dietary advisory measures are crucial to reduce the risk of potentially deleterious outcomes. HEV screening of blood donors should be maintained as an important preventive measure.