Controlling hepatitis B virus transmission in North America. The North American Regional Study Group.

In the US in 1988, 54,011 cases of viral hepatitis were reported to the Centers for Disease Control (CDC), 42% of which were categorized as hepatitis B. Because of incomplete reporting and subclinical disease, the CDC estimates that approximately 300,000 acute cases of hepatitis B are occurring in the US each year for an annual estimated incidence of 125 cases per 100,000 population. Since 1985, a gradual decrease in the reported incidence of hepatitis B has been observed which may be attributed partly to the availability of new hepatitis B vaccines. Comprehensive control of hepatitis B infection in North America has, however, been impeded by the diversity and mobility of high-risk groups who often are unaware of their potential to infect other individuals. Surveillance studies have indicated that the modes of transmission of hepatitis B may be changing in the US. A larger proportion of cases are seen in parenteral drug abusers and in active heterosexuals. It is believed that hepatitis B vaccine has been administered to only 7% of the population who are at risk of acquiring hepatitis B virus (HBV). To achieve maximum control, universal immunization of infants will therefore be necessary. A first programme, already inaugurated in the US, involves screening of all pregnant women and providing appropriate prophylaxis to neonates of hepatitis B surface antigen-positive mothers and to susceptible household contacts of these individuals. Along with mandatory guidelines, collaboration between the hepatitis community, vaccine manufacturers, the CDC and appropriate medical, legislative and health care organizations should be fostered to achieve successful control of HBV in North America.