Hepatitis C: Risks and prevention strategies in injecting drug users
CHAPTER 1 INTRODUCTION
Hepatitis C is a slow progressing disease of the liver spread by blood and blood stained body fluids. Disease progression is variable. Antibodies to the hepatitis C virus (HCV) develop several weeks after infection and usually persist through an individual's life. Around 15-20% of infected persons clear their infection spontaneously. The remaining 80-85% will become carriers of the virus. There is currently no vaccine to prevent HCV.
Chronic hepatitis C can lead to cirrhosis, liver failure and liver cancer. Estimates suggest that 20% of HCV infected individuals will have developed cirrhosis of the liver after 20 years of infection (Scottish Needs Assessment Programme 2000). Interferon alpha and ribavirin as a combination therapy is currently recommended by the National Institute for Clinical Effectiveness (NICE) for the treatment of moderate to severe hepatitis C. This treatment usually lasts for 6-12 months. A cessation of injecting drug use is usually recommended before treatment can begin. Further, treatment is not recommended for heavy alcohol users because of the increased risk of liver damage.
So, approximately 80% of those infected develop chronic hepatitis, but they may be without symptoms for many years. This means that many individuals may not be aware that they carry the disease until liver disease is well advanced. For instance, infection is sometimes detected incidentally when donating blood. This means that the potential to transmit the virus to others exists, but carriers may be unaware of the risk they pose.
There are a number of ways in which infection can be spread. These include:
treatment with contaminated blood, prior to the introduction of blood donor screening in 1991
treatment with contaminated blood products, prior to the introduction of virus inactivation in 1987
tattooing, electrolysis and body piercing, if equipment is contaminated and inadequately sterilised
needlestick injury
perinatal transmission (from mother to baby)
sexual transmission.
However, injecting drug use is the most common risk factor for HCV. Transmission is linked to the sharing of injecting equipment. The principles of HCV prevention have been largely the same as for other blood borne viruses. Indeed, HIV prevention measures are likely to have had an impact on the transmission of HCV including methadone prescribing and needle exchange schemes.
However, these strategies appear to have been less effective in containing the spread of HCV when compared to HIV (Van Beek et al 1998; Coutinho 1998). There are three main reasons for this. Firstly, a pool of HCV infection was probably established in the injecting population before harm reduction strategies were widespread. Secondly, the virus may be able to survive longer outside the body, including on injecting equipment. Thirdly, individuals with chronic HCV may be more infectious for longer periods than those individuals with HIV.
A recent study that tested for the presence of HCV RNA from injecting equipment supports the call for provision of a wider range of injecting equipment (Crofts et al 2000). This Australian study suggests that the sharing of injecting paraphernalia (other than just needles and syringes) represents a risk to health. HCV was found on swabs, filters, water samples and spoons.
The problem of HCV among injecting drug users is well recognised and there is a commitment to tackling HCV as part of the National Drugs Strategy. One of the national drugs targets, published in 2000, seeks to 'reduce the proportion of injecting drug users sharing needles and syringes by 20% by 2005, and reduce the percentage of injecting drug users testing antibody positive for hepatitis C by 20% by 2005'. There is also a target on reducing the proportion of drug misusers who inject by 20% by 2005.
This review presents data on the scale of the HCV problem among injecting drug users in Scotland and sets out the range of prevention approaches using examples from the HCV field. The review draws on information and research evidence from the Scottish Centre for Infection and Environmental Health (SCIEH), the Centre for HIV and Drug Studies (CHADS), the Health Education Board for Scotland (HEBS) and the international research literature.