Three pairs of six sporadic acute hepatitis E cases infected with three different genotype 3b hepatitis E virus strains occurred within the same economic bloc in the central region of Japan

We found three pairs of six sporadic acute hepatitis E cases infected with three different genotype 3b hepatitis E virus (HEV) strains, which were 99.7%-100% identical between two cases in each pair within the partial nucleotide sequences of ORF1 and ORF2 regions of the HEV genome. While no common source of infection was recognized within each pair, HEV infections in these cases occurred within the same economic bloc in the central region of Japan. Moreover, nucleotide sequences of the HEV strains from one pair were 99.8% identical to those obtained from pig liver sold in the same economic bloc. These results suggest the importance of continued molecular epidemiologic studies on HEV strains from humans and food products.