The objective of this study is to evaluate the efficacy of three regimens of pegylated interferon-alfa 2b (PEG-IFN) either as monotherapy or in combination with ribavirin in participants with acute hepatitis C. After 12 weeks of observation from disease onset, participants will receive one of the following regimens: (1) a 24-week course of PEG-IFN monotherapy (PEG-IFN 24); or (2) a 12-week course of PEG-IFN monotherapy (PEG-IFN-12); or (3) a 12-week course of PEG-IFN in combination with ribavirin (PEG-IFN + RVB 12). After the treatment period, participants will enter a 12-month follow-up.