Incidence of Acute Hepatitis B --- United States, 1990--2002

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Hepatitis B virus (HBV) is a bloodborne and sexually transmitted virus that is acquired by percutaneous and mucosal exposure to blood or other body fluids of an infected person. Clinical manifestations of acute hepatitis B can be severe, and serious complications (i.e., cirrhosis and liver cancer) are more likely to develop in chronically infected persons. In the United States, approximately 1.2 million persons have chronic hepatitis B virus (HBV) infection and are sources for HBV transmission to others. However, since the late 1980s, the incidence of acute hepatitis B has declined steadily, especially among vaccinated children. To characterize the epidemiology of acute hepatitis B in the United States, CDC analyzed national notifiable disease surveillance data for 1990--2002. This report summarizes the results of that analysis, which indicated that, during 1990--2002, the incidence of reported acute hepatitis B declined 67%. This decline was greatest among children and adolescents, indicating the effect of routine childhood vaccination. The decline was lowest among adults, who accounted for the majority of cases; incidence increased among adults in some age groups. To reduce HBV transmission further in the United States, hepatitis B vaccination programs are needed that target men who have sex with men (MSM), injection-drug users (IDUs), and other adults at high risk.

CDC analyzed surveillance data for acute hepatitis B cases reported weekly from state health departments and the District of Columbia during 1990--2002. Data included each patient's county of residence, sex, race/ethnicity, and age. Clinical and risk factor data were available for approximately 35% of cases reported since 1990, including death from acute hepatitis B, reported injection-drug use, sex and number of sex partners, and exposure to a household or sex contact during incubation period. Acute hepatitis B incidence was calculated by using population denominators from the U.S. Census Bureau.

Summary of Incidence

During 1990--2002, the incidence of acute hepatitis B declined 67%, from 8.5 per 100,000 population (21,102 total cases reported) to 2.8 per 100,000 population (8,064 total cases reported) (Figure). By region*, in 2002, incidence was highest in the South (3.6), followed by the Northeast (3.5), the West (2.3), and the Midwest (1.6). During 1990--2002, decreases in incidence were greatest in the West (78%), followed by the Midwest (72%), the South (59%), and the Northeast (52%); however, incidence in the Northeast has increased 41% since 1999.

The incidence of acute hepatitis B among men has been consistently higher than among women. In 1990, the incidence among men and women was 9.8 and 6.3, respectively; in 2002, the incidence was 3.7 and 2.2, respectively. Overall, incidence among women has declined more than among men; the male-to-female acute hepatitis B rate ratio was 1.5 in 1990, compared with 1.7 in 2002.

By age, the most significant decline (89%) in acute hepatitis B incidence during 1990--2002 occurred among persons aged 0--19 years, from 3.0 in 1990 to 0.3 in 2002. Among persons aged 20--39 and >40 years, acute hepatitis B incidence declined 67% and 39%, respectively; however, the majority of this decline occurred during 1990--1998. Since 1999, the incidence of acute hepatitis B has increased 5% among males aged 20--39 years and 20% and 31%, respectively, among males and females aged >40 years (Figure). Among 6,790 (32%) of the 21,102 cases reported in 1990 and 3,079 (38%) of the 8,064 cases reported in 2002 for which risk factor data were available, the proportion of persons who reported injection-drug use was similar (17% and 15%). However, the proportion of heterosexuals reporting multiple sex partners increased from 14% to 29%, as did the proportion of self-identified MSM, from 7% to 18%. During 1990--2002, the proportion of MSM reporting multiple sex partners was approximately 50%.

Examples of Local Trends

Data from two counties illustrate the changing epidemiology of acute hepatitis B in the United States. In both counties, overall incidence and incidence among children have declined. In Baltimore County (Baltimore, Maryland), acute hepatitis B incidence has been consistently higher than the national average. Since 1990, incidence has declined 26% overall; however, during 2000--2002, incidence increased 15%. In 2002, Baltimore County reported 50 acute hepatitis B cases (29 among men and 21 among women) for an overall incidence of 6.6; incidence for men and women was 8.1 and 5.3, respectively, with a male-to-female rate ratio of 1.5. Of the 38 persons with available risk factor data, 15 (40%) reported injection-drug use, eight (21%) reported having multiple heterosexual sex partners, and three (8%) reported both risk factors; six (16%) persons reported exposure to an HBV-infected household or sex contact, and three (8%) reported being an MSM.

Since 1990 in Mecklenburg County (Charlotte, North Carolina), reported acute hepatitis B incidence has been above the national average; however, during the same period, incidence has declined 82%. In 2002, Mecklenburg County reported 39 acute hepatitis B cases (28 among men and 11 among women) for an overall incidence of 5.6; incidence for men and women was 8.2 and 3.1, respectively, with a male-to-female rate ratio of 2.6. Risk factor data were available for all 39 cases; eight (21%) persons reported having multiple heterosexual sex partners, eight (21%) reported being MSM, and three (8%) reported both risk factors. Five (13%) persons reported exposure to an HBV-infected household or sex contact; no persons reported injection-drug use.

Reported by: State and local health depts. Maryland Dept of Health and Mental Hygiene. North Carolina Dept of Health and Human Svcs. J Miller, MPH, L Finelli, DrPH, BP Bell, MD, Div of Viral Hepatitis, National Center for Infectious Diseases, CDC.

Editorial Note:

In 1991, a comprehensive strategy to eliminate HBV transmission was implemented in the United States and has reduced the incidence of acute hepatitis B among children. The strategy included universal infant vaccination, universal screening of pregnant women, and postexposure prophylaxis of infants born to infected mothers to prevent perinatal HBV infection; since 1982, adolescents and adults at high risk have been recommended to receive HBV vaccine (1). In 1995, the strategy was expanded to include routine vaccination of all adolescents aged 11--12 years and, in 1999, to include all persons aged 0--18 years who had not been vaccinated previously (2). The incidence of acute hepatitis B has declined steadily during the preceding decade, in part because of successful vaccination and other prevention programs. The observed decline in the incidence of acute hepatitis B among children occurred coincident with an increase in hepatitis B vaccination coverage among children aged 19--35 months, from 16% in 1992 to 90% in 2000 (3).

Since 1999, after more than a decade of decline, hepatitis B incidence among men aged >19 years and women aged >40 years has increased. The most common risk factors reported among adults with acute hepatitis B continue to be multiple sex partners, MSM, and injection-drug use (4). Different high-risk behaviors accounted for the majority of transmissions in different locales.

Increases in sexually transmitted diseases (STD), including syphilis and human immunodeficiency virus (HIV) infection among MSM (5,6) have been attributed to increases in high-risk sexual behavior (e.g., unprotected anal intercourse with more than one partner and unsafe sex while under the influence of alcohol or recreational drugs) (5,6). Changes in patterns of sexual behavior also could be responsible for the increasing transmission of HBV among MSM.

In 1982, the Advisory Committee on Immunization Practices recommended hepatitis B vaccination for sexually active homosexual and bisexual men and IDUs and, in 1985, for heterosexuals with multiple sex partners or a recent STD (1). Trends in acute hepatitis B infection also reflect poor vaccination coverage among persons who engage in these behaviors. Of 3,432 young MSM in seven U.S. metropolitan areas, only 9% had received HBV vaccine (7). In a San Diego County, California, survey, only 6% of IDUs had completed the 3-dose HBV vaccine series (8).

Persons at high risk for HBV infection often seek health care in settings in which vaccination services could be provided. During 1996--1998, approximately half of persons reported with acute hepatitis B had been treated for an STD or incarcerated: 89% of IDUs, 35% of MSM, and 70% of persons with multiple sex partners (4,9). Both STD clinics and correctional facilities are settings in which hepatitis B vaccination services are recommended.

The findings in this report are subject to at least two limitations. First, the quality of surveillance data varies at local and state levels. Second, national viral hepatitis case-reporting is incomplete; only approximately 35% of all reported cases contain risk factor data.

The decline in acute hepatitis B among children indicates that successful hepatitis B vaccination programs are possible. These programs must consider the local epidemiology of hepatitis B and identify ways to reach populations at high risk. Integration of hepatitis B vaccination into health-care programs that target persons at high risk is feasible and cost effective (8,10). Hepatitis B vaccination programs have been implemented in STD clinics, juvenile and adult detention facilities, HIV-counseling and -testing centers, and other sites.

No national adult hepatitis B program exists that is similar to those that have proven successful for children and adolescents. Components of a national adult vaccination program must include policies for vaccination, including methods for achieving higher vaccination rates among adults at greatest risk and appropriate resources to support implementation.

References

* Northeast=Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont; Midwest=Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin; South=Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia; and West=Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.

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