Unexpected long‐lasting anti‐HEV IgM positivity: Is HEV antigen a better serological marker for hepatitis E infection diagnosis?

Hepatitis E virus (HEV) is the leading cause of acute hepatitis worldwide. The minimum criterion for diagnosis of acute infection is detection of anti‐HEV antibodies, although there are scant data on IgM duration. Our aim was to assess the persistence of HEV markers after acute self‐limited hepatitis E. HEV serological tests (IgM by Mikrogen and Wantai and HEV‐Ag) and HEV RNA were carried out in two cohorts: (a) patients with prior acute hepatitis E (ALT >10 x ULN plus positive IgM ± HEV RNA) currently self‐limited and (b) 50 blood donors with positive HEV RNA. Among 25 cases of prior acute hepatitis E, after a median follow‐up of 34 months, all presented undetectable HEV RNA. However, anti‐HEV IgM remained detectable in 14 (56%) by Mikrogen, 6 (24%) by Wantai and none for HEV‐Ag. Anti‐HEV IgM tested positive in 80%‐100% within the second year and 17%‐42% over 3 years later, by Wantai and Mikrogen, respectively. Among HEV RNA‐positive donors, 12 (25%) tested positive for either IgM by Mikrogen or Wantai, 9 (18%) for both and 18 (36%) for HEV‐Ag. HEV‐Ag positivity was more likely as HEV RNA was higher (14% if