The next wave of hepatitis C virus: The epidemic of intravenous drug use.

The epidemic of hepatitis C virus (HCV) began in the 1960s when transmission was primarily the result of blood transfusions. By 1990, when HCV was identified and a serologic test for screening donated blood was implemented, 123 million persons had already become infected worldwide and HCV was the most common cause of cirrhosis, hepatocellular carcinoma and the most common indication for liver transplantation. Approximately 75% of persons with HCV are "baby boomers" born between the years 1945 and 1965. The number of new cases of HCV declined precipitously between 1990 and 2005. The next wave of HCV began in 2005, and transmission is primarily the result of an epidemic of intravenous drug use. New cases of HCV have increased three-fold between 2005 and 2015. Approximately 50% of persons who inject drugs (PWID) have been exposed to HCV, and 25% of these persons are under the age of 25 years. The treatment of chronic HCV in PWID has two goals; treating HCV and preventing the patient from returning to drug use and becoming reinfected. Highly effective oral antiviral agents are now available and can cure HCV in virtually all patients. Treatment can be highly effective in PWID with sustained virologic response rates similar to that observed in a non-drug-using population. Preventing the patient from returning to drug use and becoming reinfected with HCV is more difficult and will require that the medical and social problems associated with intravenous drug use be addressed and resolved.