[Trends in studies of hepatitis A virus and the status of hepatitis A in Japan].
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology*; D006507:Hepatovirus / Q000302:isolation & purification; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged