The prevalence of hepatitis C virus infection in the United States, 1988 through 1994

Background Because many persons with chronic hepatitis C virus (HCV) infect ion are asymptomatic, population-based serologic studies are needed to esti mate the prevalence of the infection and to develop and evaluate prevention efforts. Methods We performed tests for antibody to HCV (anti-HCV) on serum samples from 21,241 persons six years old or older who participated in the third Na tional Health and Nutrition Examination Survey, conducted during 1988 throu gh 1994. We determined the prevalence of HCV RNA by means of nucleic acid a mplification and the genotype by means of sequencing. Results The overall prevalence of anti-HCV was 1.8 percent, corresponding t o an estimated 3.9 million persons nationwide (95 percent confidence interv al, 3.1 million to 4.8 million) with HCV infection. Sixty-five percent of t he persons with HCV infection were 30 to 49 years old. Seventy-four percent were positive for HCV RNA, indicating that an estimated 2.7 million person s in the United States (95 percent confidence interval, 2.4 million to 3.0 million) were chronically infected, of whom 73.7 percent were infected with genotype 1 (56.7 percent with genotype la, and 17.0 percent with genotype Ib). Among subjects 17 to 59 years of age, the strongest factors independen tly associated with HCV infection were illegal drug use and high-risk sexua l behavior. Other factors independently associated with infection included poverty, having had 12 or fewer years of education, and having been divorce d or separated. Neither sex nor racial-ethnic group was independently assoc iated with HCV infection. Conclusions In the United States, about 2.7 million persons are chronically infected with HCV. People who use illegal drugs or engage in high-risk sex ual behavior account for most persons with HCV infection. (N Engl J Med 199 9;341:556-62.) (C)1999, Massachusetts Medical Society.