Epidemiology of hepatitis C virus infection in Australia.

BACKGROUND: Since the discovery in 1989 of hepatitis C virus (HCV) as the infectious agent responsible for the vast majority of post-transfusion non-A non-B hepatitis the patterns of transmission and clinical consequences of this highly prevalent flavivirus have been widely studied. OBJECTIVE: This paper reviews available evidence on the epidemiology of HCV infection in Australia, including HCV notification data obtained through public health surveillance systems, HCV seroprevalence surveys among high risk populations, and models for estimating and projecting HCV transmission and long-term consequences of chronic HCV infection. RESULTS: Over the period 1990-2000 approximately 160,000 notifications of HCV infection were received by State and Territory health jurisdictions making it the most commonly notified communicable disease in Australia. Approximately 210,000 people are estimated to be living with HCV infection in Australia, with an estimated 80% having acquired their infection through injecting drug use. Less than 500 cases of newly acquired HCV infection are notified each year, however, an estimated 16,000 new infections occur annually. Despite the widespread introduction of needle and syringe programmes in the late 1980s, HCV transmission continues at high levels among current injecting drug users (IDUs) with incidence and prevalence estimates of 10-20/100 person years and 50-55%, respectively. Levels of HCV transmission are particularly high in both younger and incarcerated IDUs. In contrast to HCV infection, prevalence of HIV among current IDUs has remained below 2% since 1995. Although a small minority of people with chronic HCV infection will develop liver failure or hepatocellular carcinoma, the incidence of these advanced disease complications is estimated to double over the next decade. CONCLUSION: The epidemic of HCV infection continues to escalate in Australia, predominantly through transmission related to injecting drug use. As the population of people with chronic HCV infection and progressive liver disease expands the public health burden of advanced disease complications will be considerable.