Epidemiology of hepatitis B infection in North America.

Although the USA is considered an area of 'low' endemicity for hepatitis B infection, the incidence of new cases, the prevalence of carriers, and the burden of acute and chronic disease place hepatitis B among the most important communicable diseases. It is estimated that 300,000 new cases of hepatitis B infection occur each year. These acute infections lead to 350-450 fulminant deaths, 27,000-42,000 chronic carriers and ultimately 4000-5500 deaths per year from cirrhosis and primary liver cancer. Most reported cases occur among young adults, many of whom belong to 'high risk' groups defined by lifestyle or occupation. In 1991, sexual transmission was the predominant mode of transmission (41% of cases by heterosexual activity; 14% by homosexual activity); percutaneous drug use was also important (12% of cases). Infection in healthcare workers represented only 2% of reported cases, and is the only group where falling incidence is due to vaccine use. However, 26% of cases occur in people who deny belonging to any 'high risk group'. Public health officials in the USA concluded that the 'high risk group' immunization strategy would not lead to the control of hepatitis B infection on a population basis. In 1992, it was recommended that all newborns in the USA receive hepatitis B vaccine as part of their routine immunization schedule.(ABSTRACT TRUNCATED AT 250 WORDS)