RE: "RISK OF HEPATITIS C VIRUS AMONG YOUNG ADULT INJECTION DRUG USERS WHO SHARE INJECTION EQUIPMENT"

Stephen Koester1, Robert Heimer2, Anna E. Barón3, Jason Glanz3 and Wei Teng4

1 Department of Anthropology, University of Colorado at Denver, Denver, CO 80217-3364.
2 Department of Epidemiology and Public Health, Yale School of Medicine, New Haven, CT 06520-8034.
3 Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, CO 80262.
4 Hispanic Health Council, Hartford, CT 06106.

Recently published articles, including one appearing in the American Journal of Epidemiology, have reported that sharing of syringes by injection drug users is not strongly associated with hepatitis C virus (HCV) transmission (1, 2). Instead, these articles report a strong association between HCV transmission and the sharing of nonsyringe injection paraphernalia—namely, the "cooker" (drug mixing con-tainer) used to dissolve drugs and the cotton used to filter the solution. Both sets of authors concluded that prevention of HCV transmission requires reductions in the sharing of cotton and cookers.

However strong these associations are, if they are not supported by an understanding of biology and of the drug preparation and injection process, they may lead to erroneous conclusions. Statistical association is only one of nine standards needed to establish causality beyond a reasonable doubt (3). A correlate equally as compelling as statistical association is biologic plausibility. Since HCV is found at high titers in the blood of HCV-infected drug injectors, it makes sense to identify the source of the blood that transmits HCV. At no time during the drug preparation or injection process is blood directly introduced into cookers or cottons.

Careful examination of drug injection practices has suggested that sharing of cookers and cottons most often occurs while preparing shared drugs for injection. In doing so, one injector uses his syringe to mix the drug into solution and apportion other injection participants’ shares. Only one cooker and cotton filter are used. However, the risk of contamination does not originate in these items but from the previously used syringe. During the process of drawing up water, the contents of the dirty syringe enter the water, which is then introduced into the cooker. After the drug is dissolved, the syringe is used again to draw up through the cotton and then measure the drug solution. The preparer then squirts the other participants’ shares back into the cooker. Even though the contaminated syringe is not shared, its contents are (4, 5).

In our studies in Denver, Colorado, and southern New England, injectors of tar heroin (Denver) and powder heroin and cocaine (New England) reported having frequently shared drugs the last time they injected (64 percent (394/611) in Denver and 38.5 percent (380/988) in southern New England). This practice is common, because drug injectors pool their resources to obtain drugs; the most efficient and expedient way to then divide shared drugs is in solution. This scenario is particularly true for drug injectors in withdrawal or those injecting in locations that lack privacy (6).

We argue that, for reasons of biologic plausibility and observed behavior, simply reducing the sharing of cookers and cotton is unlikely to have a substantial impact on HCV transmission. Instead, prevention measures must focus on reducing the risks associated with drug-sharing, specifically the practices of using contaminated syringes to introduce water and apportion drugs and reusing potentially contaminated water in dissolving drugs. Increasing access to sterile syringes for both drug preparation and injection and working with drug injectors to find alternative ways to prepare and distribute shared drugs would be steps in the right direction.

REFERENCES

  1. Hagan H, Thiede H, Weiss NS, et al. Sharing of drug preparation equipment as a risk factor for hepatitis C. Am J Public Health 2001;91:42–6.[Abstract]
  2. Thorpe LE, Ouellet LJ, Hershow R, et al. Risk of hepatitis C virus infection among young adult injection drug users who share injection equipment. Am J Epidemiol 2002;155:645–53.[Abstract/Free Full Text]
  3. Hill AB. The environment and disease: association or causation? Proc R Soc Med 1965;58:295–300.[ISI][Medline]
  4. Koester S, Hoffer L. Indirect sharing: additional risks associated with drug injection. AIDS Public Pol 1994;9:100–5.
  5. Koester S. Following the blood: syringe reuse leads to blood-borne virus transmission among injection drug users. (Letter). J Acquir Immune Defic Syndr Hum Retrovirol 1998;18(suppl 1):S139–40.[Medline]
  6. Koester S, Glanz J, Baron A. Drug injection as a social process: from drug acquisition to blood-borne disease transmission. Presented at the 128th Annual Meeting of the American Public Health Association, Boston, Massachusetts, November 12–16, 2000.




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