During 35 years from 1971 to 2005, 153 patients with acute and 4,277 with chronic HBV
infection visited the Toranomon Hospital in Tokyo, Japan. They were grouped into seven 5-year periods, and HBV genotypes/subgenotypes were determined. Patients with acute HBV
infection were younger (P = 0.046), predominantly male (P = 0.004), possessed higher
alanine aminotransferase levels (P < 0.001), positive more frequently for
HBeAg (P < 0.001), and had lower HBV
DNA loads (P = 0.014) than those with
chronic infection. Sexual transmission was more frequent in patients with acute than chronic HBV
infection (67% vs. 3%, P < 0.001). The number of patients with acute
infection increased throughout 1971-2005. Patients with
chronic infection increased since 1971, peaked in 1986-1990 and then decreased. The number of patients increased since 1990-2000 again, however, reflecting recent boost of acute HBV
infection. The distribution of HBV genotypes was considerably different between patients with acute and
chronic infections (A, B, and C: 28.6%, 10.3%, and 59.5% vs. 3.0%, 12.3%, and 84.5%, respectively, P < 0.001). Since 1991, genotype A foreign to Japan started to increase sharply in patients with acute
infection, and gradually in those with
chronic infection. There was a trend for the foreign subgenotype B2/Ba to increase recently (P < 0.05). Despite immunoprophylaxis of high-risk babies born to carrier mothers with
hepatitis B e antigen, implemented nationally since 1986, acute and
chronic infections with HBV have been increasing in Japan. Based on genotypes/subgenotypes changing with time, the resurgence of
hepatitis B could be attributed to
infections, with foreign HBV genotypes/subgenotypes, spreading swiftly by sexual contact.