Clinical and molecular analyses of sporadic acute hepatitis A and E and the specific viral genotypes isolated in Iwate and three neighboring prefectures in the northern part of Honshu, Japan, between 2004 and 2013

Abstract

Aim: To examine the prevalence and characteristics of hepatitis A virus (HAV) and hepatitis E virus (HEV) infections in the northern part of Honshu, Japan, during the last decade.

Methods: Using the registration system of a prospective cohort study for acute liver injury (ALI) in Iwate and three neighboring prefectures, we examined the prevalence of sporadic acute hepatitis (AH) with HAV (AH-A) and HEV (AH-E) and the distribution of viral genotypes in 487 patients diagnosed with ALI between 2004 and 2013.

Results: Among all 487 patients, 135 (28%) had ALI with viral infection. In the cases with viral ALI, the prevalence of hepatitis B virus-related AH was highest (55.6%). AH-E was seen in 23 patients (17.0%) and its prevalence was higher than that of AH-A (10 patients, 7.4%). There were no appreciable differences in the prevalence of AH-A and AH-E between 2004-2008 and 2009-2013. However, subgenotype IIIA HAV homologous to Korean strains has recently emerged, and the number of AH-E cases seems to be increasing. HEV genotype 3 was predominant throughout the observation period, but HEV genotype 4 was found in three patients after 2010. The transmission routes of HAV and HEV infections were unknown in approximately 60% of the patients.

Conclusion: In the northern part of Honshu, Japan, HEV has been more frequently implicated in the development of AH than HAV, and HEV genotype 4 has been recently increasing. To provide an effective prophylactic management for HAV and HEV infections, further clarification of the transmission routes is needed.

Keywords: acute liver injury; acute viral hepatitis; genotype; hepatitis A virus; hepatitis E virus.