"Figure 4.5. Of the 850 case reports of acute hepatitis C received by CDC during 2010, 328 (39%) did not include a response (i.e., a ""yes"" or ""no"" response to any of the questions about risk behaviors and exposures) to enable assessment of risk behaviors or exposures. Of the 522 (61%) case reports that had complete information, 38% (n=198) indicated no risk behaviors/exposures for hepatitis C infection, and 62% (n=324) indicated at least one risk behavior/exposure for hepatitis C infection during the 6 weeks to 6 months prior to illness onset."