Hepatitis C virus genotypes and viral concentrations in participants of a general population survey in the United States.

Background & Aims: Estimates of the long-term benefits of antiviral therapies for chronic hepatitis C are influenced by the frequency of characteristics that affect response in the population treated. This study determined hepatitis C virus (HCV) genotypes and RNA titers among HCV-infected persons in the general population of the United States.

Methods: Genotypes were determined from the NS5b region, and HCV RNA was quantified by using Amplicor Monitor (Roche Diagnostic Systems, Inc, Branchburg, NJ) from 275 HCV RNA-positive participants in the Third National Health and Nutrition Examination Survey conducted during 1988 to 1994.

Results: The HCV genotypes identified included 1a (n = 142), 1b (n = 73), 2a (n = 8), 2b (n = 27), 3a (n = 17), 4 (n = 3), and 6 (n = 5). Based on weighted analysis of persons infected with genotypes 1, 2, and 3, genotype 1 predominated in all age groups (75.3%). By racial/ethnic group, genotype 1 was found in 90.9% of non-Hispanic blacks, 69.6% of non-Hispanic whites, and 71.2% of Mexican Americans. After adjusting for age and gender, only non-Hispanic black race/ethnicity was independently associated with genotype 1 infection (adjusted odds ratio 4.9; 95% confidence interval, 1.9-12.8). The overall geometric mean concentration of HCV RNA was 2.1 x 10(6) IU/mL; concentrations > 2 million IU/mL were found in 53.0% overall and 50.3% of persons with genotype 1.

Conclusions: Persons with chronic hepatitis C in the United States who may require treatment in the foreseeable future are predominantly infected with genotype 1, including a disproportionate number of non-Hispanic blacks. These features emphasize the need for improved therapies that reduce or eliminate complications from genotype 1 infections.