Dynamic Epidemiology of Acute Viral Hepatitis in Japan

Abstract

The epidemiology of acute viral hepatitis (AVH) is dynamic and affected by many factors including hygiene, socioeconomic status and vaccination coverage. A total of 4,302 cases of AVH were sequentially enrolled in this nationwide study between 1980 and 2008. Of the cases of AVH, acute hepatitis A (AHA) accounted for 1,583 (36.8%), acute hepatitis B (AHB) for 1,197 (27.8%), acute hepatitis C (AHC) for 359 (8.3%), and non-A, non-B and non-C (non-ABC) for 1,163 (27.0%). Between 1980 and 1995, the proportions of AHA, AHB, AHC and non-ABC were approximately 40, 25, 10 and 25%; between 1996 and 2003, they were approximately 30, 30, 10 and 30%, and this shifted to approximately 10, 40, 10 and 40% in the last 5 years. The number of AHB caused by genotype A, which is not indigenous to Japan, was 6.0% between 1991 and 1996 but has been markedly increasing since 2000, to reach 52% in 2008. Autochthonous acute hepatitis E (AHE) accounted for 10–15% of non-ABC hepatitis after 2002. The etiology of AVH in Japan has been drastically changing. A marked increase of AHB genotype A and constant occurrence of autochthonous AHE require attention, and necessary measures should be taken.

Comparison of improved prognosis between hepatitis B‐ and hepatitis C‐related hepatocellular carcinoma

“…In Japan, the majority of C-CH patients acquired the virus in the 1950s and 1960s, and new infections have been Comparison between HBV-and HCV-related HCC E103 Hepatology Research 2015; 45: E99-E107 extremely rare since 1990. 28 Therefore, C-CH and C-HCC patients in Japan are of advanced age. 29 The 5.8-year difference in mean ages between cohorts 1 and 3 corresponds to a 7.3% decline in the 5-year survival rate under the assumption of a HR of 1.04 per year and 60% of the baseline survival rate.…”

Does the spread of hepatitis B virus genotype A increase the risk of intrafamilial transmission in Japan?

“…The distribution of HBV genotypes A, B, C, and D in cases of chronic HBV infection in Japan was reported to be 1.7, 12.2, 84.7, and 0.4%, respectively [4]. However, the prevalence of genotype A in acute HBV infection has increased since the 1990s in Japan [5,6]. Between 2001 and 2005, the prevalence of genotype A accounted for 40% of the cases of acute HBV infection [5].…”

Viral Hepatitis A to E: An Update in 2010

“…This phenomenon may reflect the fact that their sentinels involve only a few institutes in Hokkaido, where HEV genotype 4 is endemic. Nevertheless, the trend of AHE requires particular attention, because modes of transmission are still often unknown, even after taking very careful history of eating particular foods such as raw meat of deer, pigs and boars [11] .…”