Global estimates of prevalence of HCV infection among injecting drug users

Abstract

Objective

In this paper, we review evidence of HCV prevalence among injecting drug users (IDUs) worldwide.

Methods

We undertook a desk-based review of both ‘grey’ and published literature released between 1998 and 2005.

Results

Data on HCV prevalence among IDUs was found in 57 countries and in 152 sub-national areas. We found reports of HCV prevalence of at least 50% among IDUs in 49 countries or territories. Available regional estimates varied widely, from 10 to 96% in Eastern Europe and Central Asia, from 10 to 100% in South and South–East Asia, from 34 to 93% in East-Asia and the Pacific, from 5 to 60% in North Africa and the Middle-East, from 2 to 100% in Latin America, from 8 to 90% in North America, from 25 to 88% in Australia and New Zealand, and from 2 to 93% in Western Europe. Only in Colombia and Lebanon were all HCV prevalence estimates below 20%. In addition, evidence of HIV/HCV co-infection among IDUs was found in 16 countries. In China, Poland, Puerto Rico, Russia, Spain, Switzerland, Thailand and Viet Nam, estimates of the prevalence of HIV/HCV co-infection among IDUs reached 90%.

Discussion

Taken together, data suggest high global prevalence of HCV and HIV/HCV co-infection among IDUs. We suggest exploring protective factors in sites of low HCV prevalence.

Introduction

Chronic HCV infection is a blood-borne viral infection and a major cause of liver cirrhosis and end-stage liver disease, second only to alcohol (EMCDDA, 2004). The World Health Organization (WHO) estimates that about 170 million people worldwide are infected with Hepatitis C (WHO, 2000). In 2004, we estimated that there were approximately 13.2 million injecting drug users (IDUs) worldwide (Aceijas, Stimson, Hickman, & Rhodes, 2004), and HCV has been identified as the most common viral infection affecting IDUs (Crofts, Dore, & Locarnini, 2001). Injecting drug use (IDU) is the main mode of transmission of HCV in developed countries; transmitted through blood-to-blood contact, either via direct or indirect sharing of injecting equipment (Crofts et al., 2001, Thorpe et al., 2002). HCV is estimated to be about 10 times more infectious than HIV, per unit of blood required, and therefore, requires less exposure than HIV to reach high prevalence (Crofts et al., 2001). In 2001, a review of 160 studies across 34 countries gave a weighted average HCV prevalence among 46,000 IDUs of 70% (Crofts et al., 2001), with North America and Asia having the highest prevalence (EMCDDA, 2004).

Recommendations to exclude IDUs from treatment for chronic HCV changed in light of research demonstrating treatment compliance among both active and former IDUs and those receiving methadone substitution treatment (Dalgard et al., 2002, EMCDDA, 2004), although access to treatment for this group remains limited (EMCDDA, 2004). A particular concern is rates of HCV/HIV co-infection as this complicates treatment outcome (Rhodes et al., 2006). The presence of HIV accelerates the natural course of chronic hepatitis C, including increasing the risk of liver cirrhosis, hepatocellular carcinoma, and decompensated liver disease (Rhodes et al., 2005). Below we report on the available evidence of the estimated anti-HCV prevalence and HIV/HCV co-infection among IDUs.