Different fecal shedding patterns of two common strains of hepatitis E virus at three Japanese swine farms

Zoonotic infections caused by eating the meat of deer, wild boar, and pig have been suggested in Japan, a country that is not epidemic for hepatitis E caused by hepatitis E virus (HEV). This virus is widely spread in domestic pigs in both epidemic and non-epidemic countries. We studied fecal HEV shedding patterns on three Japanese farms that had two common genotype III HEV strains. Two of the three farms had high shedding peaks (75% and 100%) in pigs 1-3 months of age, suggesting that these animals had the highest risk of spreading HEV through feces. Another farm had a low shedding rate in animals six months of age and a low prevalence of the IgG antibody to HEV. Fecal IgA antibody to HEV was found in sucking pigs < 13 days of age on farms that had high and low shedding patterns. A small fraction of pigs (3 of 43 [7%]) at the finishing stage (5-6 months of age) still shed HEV on the three farms.