Public health dispatch: multistate outbreak of hepatitis A among young adult concert attendees--United States, 2003.

In July 2003, a cluster of hepatitis A cases was identified among young adults who had attended outdoor concert and camping events featuring various "jam bands." As of September 2, a total of 25 cases have been reported among residents of nine states (Arizona, California, Colorado, Indiana, Michigan, New York, Oregon, Tennessee, and Wisconsin). The majority of cases were among young adults who attended concerts during the spring and summer. The median age of infected persons was 23 years (range: 17-44 years); 14 (56%) were male.