Surveillance for acute viral hepatitis - United States, 2007

In the United States, acute viral hepatitis most frequently is caused by infection with any of three distinct viruses: hepatitis A virus (HAV), hepatitis B virus (HBV), or hepatitis C virus (HCV). These unrelated viruses are transmitted through different routes and have different epidemiologic profiles. Safe and effective vaccines have been available for hepatitis B since 1981 and for hepatitis A since 1995. No vaccine exists against hepatitis C. HBV and HCV can persist as chronic infections and represent a leading cause of chronic liver disease and hepatocellular carcinoma in the United States.

Cases in 2007, the most recent year for which data are available, are compared with those from previous years.

Cases of acute viral hepatitis are reported voluntarily to CDC by state and territorial health departments via CDC's National Notifiable Disease Surveillance System (NNDSS). Reports are received electronically via CDC's National Electronic Telecommunications System for Surveillance (NETSS).

Acute hepatitis A incidence has declined 92%, from 12.0 cases per 100,000 population in 1995 to 1.0 case per 100,000 population in 2007, the lowest rate ever recorded. Declines were greatest among children and in those states where routine vaccination of children was recommended beginning in 1999. Acute hepatitis B incidence has declined 82%, from 8.5 cases per 100,000 population in 1990 to 1.5 cases per 100,000 population in 2007, the lowest rate ever recorded. Declines occurred among all age groups but were greatest among children aged <15 years. Following a peak in 1992, incidence of acute hepatitis C declined; however, since 2003, rates have plateaued. In 2007, as in previous years, the majority of these cases occurred among adults, and injection-drug use was the most common risk factor.

The results documented in this report suggest that implementation of the 1999 recommendations for routine childhood hepatitis A vaccination in areas of the United States with consistently elevated hepatitis A rates has reduced rates of infection. In addition, universal vaccination of children against hepatitis B beginning in 1991 has reduced disease incidence substantially among younger age groups. Higher rates of hepatitis B continue among adults, particularly among males aged 30-44 years, reflecting the need to vaccinate adults at risk for HBV infection. The decline in hepatitis C incidence after 1992 was attributable primarily to a decrease in incidence among injection-drug users. The reasons for this decrease were unknown but probably reflected changes in behavior and practices among injection-drug users.

The expansion in 2006 of recommendations for routine hepatitis A vaccination to include all children in the United States aged 12-23 months is expected to reduce hepatitis A rates further. Ongoing hepatitis B vaccination programs ultimately will eliminate domestic HBV transmission, and increased vaccination of adults with risk factors will accelerate progress toward elimination. Further prevention of hepatitis B and hepatitis C relies on identifying and preventing transmission of HBV or HCV in hospital and nonhospital health-care associated settings. In addition, prevention of hepatitis C relies on identifying and counseling uninfected persons at risk for hepatitis C (e.g., injection-drug users) regarding ways they can protect themselves from infection. Public health management of persons with chronic HBV or HCV infection will help to interrupt the transmission to susceptible persons, and their medical management will help to reduce the development of the sequelae from chronic liver disease.