Very low prevalence of anti-HAV in Japan: high potential for future outbreak

Chikako Yamamoto,Hiroaki Okamoto,Takayuki Harakawa,Keiko Katayama,Ko Ko,Kazuaki Takahashi,Junko Tanaka,Shintaro Nagashima,Masayuki Ohisa,Toshiko Fujii

doi:10.1038/s41598-018-37349-1

Abstract

Since the early 21st century, almost all developed countries have had a very low hepatitis A virus antibody (anti-HAV) sero-prevalence profile, as sanitation conditions and health care facilities have been optimized to a universal standard. There has not been a report on anti-HAV prevalence among a large scale population in Japan since 2003. Therefore, this study aimed to investigate the current HAV status among the general population in Hiroshima. From each age and sex specific group, a total of 1,200 samples were randomly selected from 7,682 stocked serum samples from residents’ and employees’ annual health check-ups during 2013–2015. Total anti-HAV was detected using Chemiluminescent Enzyme Immunoassay. The overall anti-HAV sero-prevalence was 16.8%. In both males and females, anti-HAV prevalence among individuals between 20–59 years of age was as low as 0.0–2.0%, whilst that among 70 s was as high as 70.0–71.0%. A large number of residents aged under 60 are now susceptible to HAV infection. The cohort reduction trend of anti-HAV in Japan exposes the high possibility of mass outbreak in the future. HAV vaccine especially to younger generation and high risk population may prevent outbreak in Japan.

Highlights

Hepatitis A virus (HAV) infection occurs sporadically and is primarily transmitted via the fecal-oral route, bearing a high potential for either cyclic recurrence or explosive worldwide spread as an epidemic, especially in the case of a food or waterborne outbreak[1]
HAV particles were first discovered in stool specimens of acute hepatitis cases using immunoelectron microscopy in 197315
HAV exists in a lipid-enveloped (LE) form in human plasma[16], this virus is 27 nm long, spherical particle containing a linear, single-stranded, and positive-sense RNA genome classified in the genus Hepatovirus of the family Picornaviridae, which remains infectious for significant periods on surfaces, in the environment, and in uncooked food[8]

Summary

Introduction

Hepatitis A virus (HAV) infection occurs sporadically and is primarily transmitted via the fecal-oral route, bearing a high potential for either cyclic recurrence or explosive worldwide spread as an epidemic, especially in the case of a food or waterborne outbreak[1]. It has been estimated that millions people worldwide are infected with HAV each year. The severity of HAV infection greatly depends on the age at the time of viral entry. The severity of disease increases with age; more than 53% of adults ≥60 years old require hospitalization for acute hepatitis[8]. With a high proportion of the population not immune to HAV, deterioration in existing sanitation and water supply could lead to a massive transmission of HAV. HAV endemicity levels vary worldwide, and regions are separated into three main categories: high, intermediate, and low endemic areas. These three regions indirectly indicate the socioeconomic level, including the www.nature.com/scientificreports/

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