Based upon surveillance data and modeling, CDC estimates that there has been an 82% decline in incidence of acute HBV infection since 1990 with the total number of new infections in 2007 estimated at 43,000 (Daniels et al., 2009). Because many children have been vaccinated against HBV, most reported cases of acute HBV infection are in adults. The national strategy for preventing HBV transmission in adults—by recommending hepatitis B vaccination selectively for high-risk adults (including men who have sex with men, IDUs, and correctional-facility inmates)—has had only little success in reducing the incidence of acute HBV infection in US adults (Mast et al., 2006). Acute HBV infections are often asymptomatic or have symptoms similar to those of other common illnesses, such as influenza, so there is a high probability of underreporting.
In the United States, data on reported cases of acute HBV infection in 2007 indicate that the highest rate of infection is in non-Hispanic black men: 2.3 per 100,000. The incidence is substantially lower in other populations: 0.9 per 100,000 Asians and Pacific Islanders (APIs) and 1.0 per 100,000 non-Hispanic whites and Hispanics. There also appear to be geographic variations in incidence; the highest rates of acute HBV infection are in the South1 (Daniels et al., 2009).
Although the incidence of acute HBV infection is declining in the United States, the number of people who are living with chronic HBV infection may be increasing as a result of immigration from highly endemic countries (that is, the hepatitis B surface antigen prevalence is 2%). On the basis of immigration patterns in the last decade, it is estimated that every year 40,000–45,000 people enter the United States legally from HBV-endemic countries (Mast et al., 2006; U.S. Department of Homeland Security, 2009). Some populations are at higher risk for chronic HBV infection, including API Americans, who make up only 4.5% of the general US population (U.S. Census Bureau, 2008) but account for more than 50% of Americans who are living with chronic HBV infection (CDC, 2009c). The prevalence of chronic HBV infection in API Americans is as high as 15% in some studies and constitutes an important health disparity (CDC, 2006). Having been born in an HBV-endemic country appears to be the major risk factor for chronic HBV infection in the API population (Lin et al., 2007).
Recent studies suggest that routine HBV testing of all adult API Americans is cost-effective (Hutton et al., 2007), but almost two-thirds of chronically infected API Americans are unaware of their infection status because they have not been tested for HBV (CDC, 2006; Lin et al., 2007).