The significantly younger population included in the group of patients with serological markers for HEV and other hepatitis viruses may be explained by the higher incidence of infectious mononucleosis and hepatitis A in younger age groups compared to hepatitis E, correlated to the possible false-positive results of anti-HEV IgM antibody assays in patients with acute EBV and/or HAV infections. Here, CD40LG is linked to infectious mononucleosis.