Epidemiology and natural history of hepatitis C virus infection in injection drug users: implications for treatment.

Effective methods to diminish the burden of hepatitis C virus (HCV) infection among injection drug users (IDUs) require consideration of the epidemiology and natural history of both hepatitis C and drug use. Most HCV infections are due to injection drug use, and most IDUs have HCV infection. In addition, HCV infection often occurs with other medical problems, such as human immunodeficiency virus infection and depression, which may complicate its recognition and management. Infection with HCV can be fatal, but usually not until years later, and persons may be unaware of the infection, allowing an individual to infect many others. Effective treatment is available for HCV infection; however, the therapy is prolonged, involving both weekly injections and daily oral medication, and is typically associated with significant adverse effects, such as fatigue, depression, and, rarely, life-threatening complications. Although clearly some IDUs want their HCV infection to be treated, many are unwilling or unable to initiate or sustain treatment with currently available therapies, and IDUs who are treated require considerable, multidimensional support. Solutions to the problem of HCV infection among IDUs must account for these facts.