Two cases of sporadic acute hepatitis E in Mie, Japan who were infected with subgenotype 1a hepatitis E virus

In 2015, we have seen two cases of sporadic acute hepatitis E in northern and central district of Mie prefecture, Japan. Case No.1 was a 28-year-old Nepalese man and diagnosed with imported hepatitis E, while case No. 2 was a 30-year-old Japanese man, who had no history of travel abroad within one year before the disease onset and genotype 1a strain was recovered from his serum regardless of staying in Japan at the incubation period. The HEV strains recovered from these two patients were 93.2% identical to each other in the 412-nucleotide sequence within ORF2 and did not belong to the same cluster. Case No. 1 was typical imported infectious hepatitis E disease, however, case No. 2 did not have any evidence of imported infectious disease. This result suggests that genotyping of hepatitis E virus strain is necessary for a more accurate analysis even if a patient has no history of going or living abroad.