ONCE MORE UNTO THE BREACH: CONTROLLING HEPATITIS C IN INJECTING DRUG USERS

After a decade of efforts to control the often spectacular epidemics of HIV among IDUs, it is difficult to contemplate intensifying the fight to counter other blood-borne viral infections, including hepatitis C.

HIV irrevocably changed injecting drug use (IDU) and the way we think about drugs. Hepatitis C will cause a further re-appraisal. Where will the battle to bring the epidemic of hepatitis C under control lead us?

Should we even consider attempting to control hepatitis C among IDUs? Surely the HIV epidemic has generated more than enough challenges to existing policies and programmes, amply justified by the substantial health, social and economic problems which result from uncontrolled epidemics among IDU populations.

More than 60% of IDUs in Australia were already infected with hepatitis C over two decades ago.[1] Health and other costs arising from these earlier cases of hepatitis C infection are not striking yet but this is partly because drug injecting was much less common 20 years ago. Also, many a temporary IDU of yesteryear has now metamorphosed into a middle-aged yuppie with liver disease of insidious onset. The connection of these cases with IDU and needle sharing is therefore easily overlooked.

Hepatitis C seroprevalence in IDUs of the order of 60-80% has been reported from a number of developed countries[2-9] with annual incidence in the 10-40% range.[2-4] Hepatitis C seems universally far more prevalent than HIV among IDUs. It is estimated that as a result of injecting drug use, at least 100 000 Australians are currently infected with hepatitis C and 10 000 new infections related to injecting drug use occur each year in a country with a population of only 18 million.[3] In contrast, the prevalence of HIV in Australia is estimated at around 19000 with annual incidence estimated at approximately 600 (of which IDUs comprise 10% or less.[10] Since the introduction of universal screening in blood banks in most developed countries beginning in 1990, there are believed to be very few new cases of hepatitis C associated with transfusion of blood or blood products. The major risk factor for hepatitis C in the industrialized world is now sharing of injecting equipment followed by commercial tattooing.[11,12] A few additional cases are attributed to occupational exposure in health care professionals[13] and sexual transmission with a proportion (which varies considerably between different countries) of sporadic cases.

Less is known of the natural history of hepatitis C than of HIV for several reasons. Serological tests for hepatitis C only became available several years after HIV. Improving sensitivity and specificity of successive generations of hepatitis C tests complicates assessment of the literature. The natural history of the six genotypically distinct forms of hepatitis C may differ considerably.[14] Risk group may also influence outcome.[15]

Chronic infection is estimated to follow in at least 80% of hepatitis C infections. Debilitating chronic fatigue is distressingly common and often precludes employment or home duties. In a study of 131 patients with post-transfusion hepatitis C, fatigue was noted in 88 and was present in 50% with chronic or chronic active hepatitis and 75% of those with cirrhosis.[16] At least 20% of chronic carriers develop cirrhosis within 20 years[17,18] and a small proportion of these develop hepatocellular carcinoma. Complications arising from HIV occur more quickly and involve a higher proportion of those infected than is the case with hepatitis C. The combination of a larger pool size of infected individuals and more protracted complications leads to the perhaps unexpected conclusion that the net health and economic cost of hepatitis C may even be roughly comparable with HIV.

Alarmingly extensive and in many cases rapid spread of HIV has been documented among (and from) IDU populations in diverse areas including Asia[19] (north east India, Thailand, Malaysia, Burma, south west China), the north east United States and southern Europe. Nevertheless, probably only a small fraction of the global population of IDUs, estimated to number more than 5 million,[20] is presently infected with HIV. Furthermore, after less than a decade, the epidemic of HIV among IDUs in Edinburgh appears to be back under control[21-23] suggesting that provided that there is the political will to do so, retaining and even regaining control of HIV epidemics among IDUs is not as difficult as was originally thought.

Preventing epidemic spread of hepatitis C among IDUs is a different story. A hepatitis C vaccine presently seems a remote possibility.[24] Furthermore, high hepatitis C incidence rates have been reported in a number of Australian studies, despite widespread implementation of prevention strategies which appear to have been adequate to maintain a low prevalence of HIV. Not only is hepatitis C far more prevalent than HIV in most IDU populations, the hepatitis C virus is also far more infectious than HIV in terms of blood-borne transmission.13 Taken together, these factors suggest that even minimal levels of needle sharing may be sufficient to maintain epidemic spread of hepatitis C and raise the possibility that spread may well continue in the absence of needle sharing.[25] Although dramatic reduction in injecting risk behaviour has taken place in the last decade in many countries, lower levels of unsafe injecting continue in small social networks.[26,27]

Unapparent and accidental sharing of injection equipment and paraphernalia probably occurs commonly. The extent of these practices is presently unknown but it is likely that they will be almost impossible to abolish. The far higher baseline seroprevalence and order of magnitude greater infectiousness of hepatitis C suggests that simply intensifying measures[28] which have so effectively controlled HIV may not achieve the same result with hepatitis C.

If controlling hepatitis C among IDUs requires the virtual elimination of needle sharing, this must then mean the almost complete eradication of drug injecting. This in turn will require either virtually eradicating illicit drug use or eliminating the practice of injecting (despite continuing illicit drug use). The prospect of eradicating illicit drug use is so remote that further consideration is unwarranted. Eradicating drug injecting could be achieved by drug injectors changing to non-parenteral routes of administration such as smoking, snorting, sniffing or swallowing? Attempting to engineer such transitions seems inconceivable for many reasons. Our understanding of the factors influencing these transitions in either direction is poor and presently inadequate to attempt their manipulation. Also, facilitating a transition to safer drug administration routes hardly appears to be an objective that governments could ever countenance. Although this objective may seem fanciful, sizeable risk reduction in IDUs during the past decade should provide considerable encouragement. Moreover, transitions to non-parenteral routes without government prompting have occurred in the last decade in the United States, Netherlands[30] and Britain,[31] although minimally documented and poorly understood. Fear of HIV was probably an important factor for this transition in the United States but the timing in the Netherlands and Britain suggests that other factors were more important. Rapid falls in price and increases in purity of street heroin and cocaine have probably also contributed to these transitions. The real price of cocaine per gram in the United States fell by 80% between 1977 and 199232 with similar changes observed for heroin. The fact that the estimated number of cocaine in the United States users fell 32 while the real price of cocaine declined contradicts the widely held view that falling drug prices are inevitably accompanied by increased recruitment of users.

A decade after the introduction of anti-opium laws in Hong Kong (1949), Thailand (1959) and Laos (1971), opium smoking was replaced by heroin injecting.[33] Anti-opium laws turned out inadvertently to be not only pro-heroin,[33] but also pro-HIV. We cannot assume that the transition from less to more hazardous routes of administration will be as smoothly reversed by liberalised drug policies. However, a combination of heightened fear of adverse health effects associated with injecting and affordable, non-parenteral routes of administration may well shift at least some injectors to less hazardous alternatives without necessarily recruiting new illicit drug users. Reduction in price and increasing purity of street drugs could be expected following less stringent law enforcement (although these changes occurred in the United States in recent decades despite intensified law enforcement). Less emphasis on illicit drug law enforcement could be made politically less unattractive by simply diverting law enforcement resources from drugs to other areas such as violent crime. Lower-priced street drugs are likely to result in less crime, making this proposition more palatable. Overdose is the major cause of drug-related deaths (in populations where HIV has not become established) with a reduction in these deaths another likely bonus of non-parenteral administration routes replacing injecting,[30] as dose titration is much more difficult when injecting.

Computer modelling techniques were used recently to demonstrate that expanded cocaine drug treatment significantly and cost-effectively reduces demand for illicit drugs and was remarkably more effective than law enforcement in the United States.[32] Falling demand should logically lead to a decrease in price and an increase in purity of street drugs. Changes in societal cost per dollar spent were estimated at 15 cents for source country activities, 32 cents for interdiction, 52 cents for domestic law enforcement and $7.48 for cocaine drug treatment. The most cost-effective measure, drug treatment, was only allocated 7% of the US$13 billion expended in 1992 responding to cocaine.[32] Given the compelling evidence of effectiveness of methadone maintenance, treatment for heroin dependent users is likely to be several times more cost-effective than current treatment for cocaine users.

Thinking about how we might try to control hepatitis C raises more questions than we can presently answer, but these questions, like hepatitis C, are not going to disappear. One inescapable conclusion is that the importance of the epidemic of hepatitis C among IDUs has to date been seriously underestimated.

References

1. MOAVEN, L. D., CROFTS, N. & LOCARNINI, S. A. (1993) Hepatitis C virus in Victorian injecting drag users in 1971 (letter), Medical Journal of Australia, 158, 574.

2. VAN AMEIJDEN, E. J. C., VAN DEN HOEK, J. A. R., MIENTJES, G-H. C. & COUTINHO, R. A. (1993) A longitudinal study on the incidence and transmission patterns of HIV, HBV and HCV infection among drag users in Amsterdam, European Journal of Epidemiology, 9, 255-262.

3. CROFTS, N., HOPPER, J. L., BOWDEN, D. S., BRESCHKIN, A.M., MILNER, R. & LOCARNINI, S. A. (1993) Hepatitis C virus infection among a cohort of Victorian injecting drug users, Medical Journal of Australia, 159, 237-241.

4. CROFTS, N., STEWART, T., HEARNE, P., PING, X. Y., BRESCHKIN, A.M. & LOCARNINI, S. A., (1995) Spread of blood borne viruses among Australian prison entrants, British Medical Journal, 310, 285288.

5. ESTEBAN, J. I., ESTEBAN, R., VILADOMIU, C. et al. (1989) Hepatitis C Virus antibodies among risk groups in Spain, Lancet, ii (8658), 294-297.

6. HOLSEN, D. S., HARTHUG, S. & MYRMEL, H. (1993) Prevalence of antibodies to hepatitis C virus in association with intravenous drug abuse and tattooing in a national prison in Norway, European Journal of Clinical Microbiology and Infectious Diseases, 12, 673-676.

7. MAJID, A., HOLMES, R., DESSELBERGER, U., SIMMONDS, P. & MCKEE, T. A. (1995) Molecular epidemiology of hepatitis C virus infection among intravenous drug users in rural communities, Journal of Medical Virology, 46, 48-51.

8. MAAYAN, S., SHUFMAN, E. N., ENGLEHARD, D., & SHOUVAL, D. (1994) Exposure to hepatitis B and C and to HTLV-1 and 2 among Israeli drug abusers in Jerusalem, Addiction, 89, 869 874.

9. ROBINSON, G. M., REYNOLDS, J. N. & ROBINSON, B. J. (1995) Hepatitis C prevalence and needle/ syringe sharing behaviours in recent onset injecting drug users, New Zealand Journal of Medicine, 108, 103-105.

10. CROFTS, N., BALLARD, J., CHETWYND, J., DICKSON, N., LINDBERG, W. & WATSON, C. (1994) Involving the communities: AIDS in Australia and New Zealand, AIDS, 8 (Suppl. 2), S45-S54.

11. KALDOR, J. M., ARCHER, O. T., BURING, M. L. et al. (1992) Risk factors for hepatitis C infection in blood donors: a case control study, Medical Journal of Australia, 157, 227-230.

12. Ko, Y.-C., Ho, M.-S., CHIANG, T.-A., CHANG, S.-J. & CHANG, P.-Y. (1992) Tattooing as a risk of hepatitis C virus infection, Journal of Medical Virology, 38, 288-291.

13. GERBEDING, J. L. (1995) Drug therapy: management of occupational exposures to blood-home viruses, New England Journal of Medicine, 332, 444-451.

14. YOSHIOKA, K., KAKUMU, S., WAKITA, T. et al. (1992) Detection of hepatitis C virus by polymerase chain reaction and response to alpha interferon therapy: relationship to genotypes of hepatitis C virus, Hepatology, 16, 293-299.

Source: Addiction, Feb96, Vol. 91 Issue 2, p181, 4p.

Item Number: 9604102937

HepC BC