Spreading of viral hepatitis in Bulgaria for the 1952-1964 period.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002031:Bulgaria; D002648:Child; D002675:Child, Preschool; D006506:Hepatitis A / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D012621:Seasons