Hepatitis C cluster in young injection drug users in a rural Midwestern county: Investigation and public health response

Background: Investigation of, and response to, a large cluster of hepatitis C cases in 2010 and 2011 in a rural Wisconsin county present circumstances, challenges, and lessons that apply nationally. Shifting demographics: HCV case reports in Wisconsin increased by 8% from 2006 to 2010 with a concomitant increase from 2000 to 2010 in the percentage of cases under age 30 (from 5% to 18%) and in females (from 31% to 39%). The geographic center of HCV moved northwest during the period, away from Milwaukee, the state's largest city. HCV Cluster: The county averaged 18 HCV cases in 2004-09, (19% < age 30), 36 cases in 2010, and 65 preliminary cases in 2011 (35% < age 30). As of the end of 2011, the LHD had compiled a list of 180 individuals—82 HCV cases, 55 HCV-negative partners, and 43 not yet tested for HCV. The large number of cases was driven by individuals seeking testing at the LHD and in jail after hearing about an increase in cases of both HCV and HIV in their injection drug using (IDU) networks. Excellent working relationships among the LHD, the police department drug unit, and the AIDS services organization that distributes clean syringes have facilitated a community norm in which IDUs seek HCV and HIV testing and name partners. Social network software: Investigators used UCINET to visualize the cluster and to identify and prioritize follow-up with HCV-negative and untested individuals at greatest risk, namely those with the largest number of connections to HCV cases.