Archival Content: 1999-2005
Syringe Disinfection for Injection Drug Users
For 20 years, syringe disinfection has been a part of HIV prevention efforts for injection drug users (IDUs). Questions about it persist, however, because of limited scientific studies, varying recommendations on the right way to disinfect, and evidence suggesting that IDUs do not use this approach very much. This fact sheet presents basic information on disinfection, especially bleach disinfection. The central message is that disinfection is a back-up prevention strategy if the user cannot stop injecting; does not have a new, sterile syringe; and is about to inject with a syringe that has been used before.
How Did Disinfection Become a Widely-used HIV Prevention Strategy?
The strategy of disinfecting syringes to prevent HIV emerged in California in the 1980s. East Coast epidemics among IDUs (especially in New York) made public health officials fear that HIV would be a major threat to California IDUs.
California IDUs, like those in other parts of the country, shared and reused syringes, in part because it was hard for them to get new, sterile ones. This greatly increased their risk of HIV transmission. State law made it illegal for drug users to buy syringes from pharmacies and a crime to possess them. Restricted access to sterile syringes, combined with limited capacity of substance abuse treatment programs, forced prevention programs to focus on reducing injection-related risks among IDUs who would not or could not stop injecting. Field research in California showed that IDUs would act to reduce their risks if acceptable measures were available to them. One such measure was syringe disinfection with household bleach. (Disinfection means using something to kill viruses and bacteria that cause infection.) Laboratory tests had shown that bleach killed HIV. Bleach also was cheap, quick, and available everywhere.
This led community programs to train outreach workers to teach IDUs how they could reduce the risk of infection by disinfecting their syringes and needles.
Distribution of bleach kits — small (usually 1-oz. size) bottles of full strength household bleach with instructions on how to disinfect syringes — quickly became a standard component of IDU prevention in San Francisco. Other U.S. cities then rapidly adopted this strategy.
How Disinfection Can Reduce Transmission Risk: It Reduces the Number of Viruses and It Kills Them
Current disinfection recommendations are based on the following steps:
The idea behind these steps is to reduce the risk of HIV transmission in two ways. First, flushing removes blood and drugs from the syringe, which reduces the number of viral particles. Second, using a disinfectant can kill remaining viruses so they can’t infect anyone else. Instructions for disinfecting syringes usually include ways to make sure that viruses are removed and killed:
Does Disinfection Work Against Viral Hepatitis?
Hepatitis B virus (HBV) and hepatitis C virus (HCV) cause serious illness among millions of people. They also are closely connected with HIV, injection drug use, and high-risk sexual behaviors. Many people think that disinfection doesn’t work against HBV or HCV, but laboratory studies on HBV show that disinfection works against this bloodborne virus in the same ways that it does against HIV.
An important thing to remember about HBV and HCV is that the numbers of viruses in blood are much higher for HBV and HCV than they are for HIV. As a result, getting rid of as much blood as possible by flushing out and rinsing is especially important in reducing the risk of becoming infected with viral hepatitis.
Disinfection Seems to Make Sense. What’s the Problem?
A Disinfected Syringe is NOT a Sterile Syringe
If it is done carefully and thoroughly, disinfection can reduce the amount of live HIV, HBV, and HCV in a syringe. However, even the best disinfection procedure cannot guarantee that all viruses have been killed. The plastic syringes usually used by IDUs are designed for one-time use. They are not designed to be cleaned and used again.
Disinfected syringes do NOT meet the standards that are applied in all other settings in which people use syringes (such as hospitals, other health care settings, and insulin injections by people with diabetes). In these settings, people must use a new, sterile syringe for every injection.
For these reasons, a disinfected syringe is NOT as safe as a new, sterile syringe. Recommendations about disinfecting syringes with bleach or others agents apply ONLY to situations in which IDUs do not have sterile syringes.
Scientists Have Limited Laboratory Evidence that Disinfection Works Against HIV in Syringes and Other Injection Equipment
Scientists have published a small number of laboratory studies on the ability of bleach and other agents to kill HIV. These experiments try to mimic conditions faced by IDUs and usually test the impact of disinfection on blood to which HIV grown in a test tube has been added.
However, these conditions are not the same as those faced by IDUs, and findings are not definitive. In laboratory studies, fresh undiluted household bleach (5.25% sodium hypochlorite) appears to kill HIV pretty well. Scientists also have tested whether other liquids can disinfect syringes. These liquids, which are sometimes used by IDUs, include dish detergent, rubbing alcohol, hydrogen peroxide, and fortified wine. Results of these few studies are limited.
Some research has found that even several vigorous rinses with clean water may be as effective as undiluted household bleach because they do a good job of reducing the number of infectious viruses.
Results of these studies depend on many things, including the strength of the agent, whether the HIV is in whole blood or by itself, and the steps used. Because few laboratory studies have been published, we have only limited data on disinfection as it is done by IDUs. As a result, we don’t have clear answers to questions about which agents work best, the best disinfection procedures, or the time necessary for adequate disinfection.
Laboratory studies of the effect of disinfection on HBV and HCV are difficult because these viruses cannot be grown in a test tube. Studies with animals have shown that disinfection can prevent HBV transmission. Because HBV and HCV are similar, these findings may also be true for HCV. However, it's important to note that conditions in animal studies are not the same as those faced by IDUs.
Studies of IDUs Do Not Prove That Bleach Disinfection Protects them Against HIV or Viral Hepatitis
Studies have looked for differences in the number of new infections between injectors who say they always disinfect and injectors who say they do not disinfect. They have found no significant difference in new infections among IDUs in the two groups. Several factors may help explain these findings.
Barriers Make it Hard for IDUs to Disinfect Correctly and Can Prevent Them from Doing It At All
IDUs may agree that disinfection is a good idea if they cannot get new, sterile syringes. However, some investigators have found that few IDUs actually use bleach to disinfect syringes or they don’t go through all the recommended steps if they do use it. Many factors make it hard for IDUs to disinfect:
What are the Take-Home Messages?
What Should We Tell IDUs?
Education and outreach workers should stress the following messages when they talk to IDUs:
To Learn More about This Topic
See the July 1994 issue of the Journal of Acquired Immune Deficiency Syndromes. This issue of the Journal includes seven papers from a workshop on the use of bleach to disinfect drug injection equipment. The papers provide an historical perspective on the use of bleach in HIV/AIDS prevention activities, review results of laboratory studies on the effectiveness of various agents in inactivating HIV, and describe the results of field studies on the disinfection practices of IDUs. (Journal of Acquired Immune Deficiency Syndromes 1994;7(7):741-776.)
See the April 1993 CDC/CSAT/NIDA HIV/AIDS Prevention Bulletin.This publication reviews the topic of disinfection and concludes that stopping injection or using new, sterile syringes is superior to disinfection. (Curran JC, Scheckel LW, Millstein RA. HIV/AIDS prevention bulletin. Centers for Disease Control, Center for Substance Abuse Treatment, and National Institute on Drug Abuse, April 19, 1993.) www.cdc.gov/idu/pubs/bleach_letter.htm
Check out these sources of information:
Abdala N, Crowe M, Tolstov Y, Heimer R. Survival of human immunodeficiency virus type 1 after rinsing injection syringes with different cleaning solutions. Substance Use & Misuse 2004;39(4):581-600.
Abdala N, Gleghorn AA, Carney JM, Heimer R. Can HIV-1-contaminated syringes be disinfected? Implications for transmission among injection drug users. Journal of Acquired Immune Deficiency Syndromes 2001;28(5):487-494.
Bourgois P. Anthropology and epidemiology on drugs: the challenges of crossmethodological and theoretical dialogue. The International Journal of Drug Policy 2002;13(4):259-269.
Centers for Disease Control and Prevention. Recommendations for prevention and control of hepatitis C virus (HCV) infection and HCV-related chronic disease. Morbidity and Mortality Weekly Report 1998;47(RR 19):1-39.
Ciccarone D, Bourgois P. Explaining the geographical variation of HIV among injection drug users in the United States. Substance Use & Misuse 2003;38(14):2049-2063.
Clatts MC, Heimer R, Abdala N, et al. HIV-1 transmission in injection paraphernalia: heating drug solutions may inactivate HIV-1. Journal of Acquired Immune Deficiency Syndromes 1999;22(2):194-199.
Hagan H, Thiede H. Does bleach disinfection of syringes help prevent hepatitis C virus transmission? [letter] Epidemiology 2003;14(5):628-629.
Hagan H, Thiede H, Weiss NS, et al. Sharing of drug preparation equipment as a risk factor for hepatitis C. American Journal of Public Health 2001;91(1):42-46.
Hughes RA. Drug injectors and the cleaning of needles and syringes. European Addiction Research 2000;6(1):20-30.
Kapadia F, Vlahov D, Des Jarlais DC, et al. Does bleach disinfection of syringes protect against hepatitis C infection among young adult injection drug users? Epidemiology 2002;13(6):738-741.
Koester SK. Following the blood: syringe reuse leads to blood borne virus transmission among injection drug users. [letter] Journal of Acquired Immune Deficiency Syndromes and Human Retrovirology 1998;18(Suppl 1):S139-S140.
Normand J, Vlahov D, Moses LE, eds. Preventing HIV transmission: the role of sterile needles and bleach. Washington, DC: National Academy Press, 1995. Chapter 6, The effectiveness of bleach as a disinfectant of injection drug equipment.
Sattar SA, Tetro J, Springthorpe VS, Giulivi A. Preventing the spread of hepatitis B and C viruses: Where are germicides relevant? American Journal of Infection Control 2001;29(3):187-197.
Thorpe LE, Ouellet LJ, Hershow R, et al. Risk of hepatitis C virus infection among young adult injection drug users who share injection equipment. American Journal of Epidemiology 2002;155(7):645- 653.
United States Public Health Service (USPHS). HIV prevention bulletin: medical advice for persons who inject illicit drugs. Atlanta (GA) and Rockville (MD): USPHS, May 9, 1997.
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