Over the last 2 decades, successful public health interventions have altered the epidemiology of viral hepatitis in the United States. Vaccination of children and adolescents has reduced the incidence of hepatitis A virus (HAV) and hepatitis B virus (HBV) infections to historic lows. American Indians/Alaskan Natives, a population whose HBV rate was once 5 times that of other racial/ethnic populations, now has the lowest (0.5 cases per 100 000).1–3 Since the adoption in 1991 of a strategy to eliminate HBV transmission, HBV vaccination of infants, children, and adolescents has largely contributed to an 81% decline in new cases of HBV, and infant HBV vaccination is now on par with that of other vaccines in the childhood schedule. (1,2,4,5) With more than 90% of pregnant women screened for HBV infection and postexposure prophylaxis 85% to 95% effective in preventing mother-to-child HBV transmission at delivery, substantial progress has been made in the prevention of perinatal HBV infections.4 In the absence of a vaccine to prevent HCV, the advent of laboratory testing in 1992 to protect the nation’s blood supply and prevention efforts to reduce risk behaviors among injection drug users (IDUs) have led to a 78% decline in new HCV infections.1,2,6 Health care–related transmission of HBV and HCV is now rare thanks to widespread vaccination of health care workers and the adoption of universal infection control procedures.7 Although these prevention successes are remarkable, challenges remain. Despite the existence of risk-based vaccination recommendations, HAV and HBV infections remain common.3,5 In 2006, an estimated 32000 persons were infected with HAV, with risks highest among international travelers, individuals in close contact with infected persons, men who have sex with men, and IDUs; food-borne outbreaks also continue to be reported.2 Of an estimated 46000 new HBV infections in 2006, more than 80% were attributable to injection drug use and high-risk sexual activity.2,5 Children continue to be infected at birth. Of approximately 24000 infants born to HBV-infected women annually, only about one quarter complete case management and are tested for infection or susceptibility (CDC, unpublished data, 2007). In 2006, a total of 86 perinatal HBV cases were reported to the CDC, but testing and reporting are incomplete; thus, the true number of perinatal HBV cases per year is likely 10 to 20 times higher. Approximately half of persons with chronic HBV in the United States are Asian Americans (CDC, unpublished data, 2006). HBV-related liver cancer is a leading cause of cancer deaths in this population.8 Although the incidence of HBV infection in the United States is declining, the prevalence of chronic HBV is sustained by immigration from HBV-endemic countries in Asia, Africa, and Eastern Europe; each year, an estimated 40000 persons with chronic HBV immigrate to the United States from these countries.5 In 2006, approximately 20000 persons were infected with HCV.2 Injection drug use was responsible for most of these new cases, and at least one third of IDUs are HCV infected.9 Despite the decline in the number of new infections, the number of persons with chronic viral hepatitis is over 4 million, including 3.2 million chronic HCV infections and 800 000 to 1.4 million chronic HBV infections (CDC, unpublished data, 2006).10 Chronic viral hepatitis is a major cause of morbidity responsible for approximately two thirds of chronic liver disease and conservatively 9000 deaths per year. 11,12 Mortality from HCV is expected to rise as the HCV-infected population ages, extending their years of living with the infection and increasing their risk of liver cirrhosis and cancer.13 Cofactors such as HIV infection and alcohol use accelerate the progression of HCV; approximately 25% of the 1 million persons infected with HIV are co-infected with HCV.6 Finally, cases of health care–associated HBV and HCV transmission continue to occur. The changing epidemiology of viral hepatitis reveals both gaps in the delivery of proven interventions and new opportunities to reduce the health consequences of chronic disease. The Centers for Disease Control and Prevention (CDC) has identified new priorities to improve current programs and develop new prevention goals.
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