The 25 countries and territories with at least one report of HIV prevalence of 20% or more at the ‘national', ‘capital city’ or ‘other sites’ levels were: Belarus, Estonia, Kazakhstan, Russia, Ukraine (in Eastern Europe and Central Asia), Italy, Netherlands, Portugal, Serbia and Montenegro and Spain (in Western Europe), Libya (in North Africa and the Middle East), India, Indonesia, Malaysia, Myanmar, Nepal, Thailand and Viet Nam (in South and South-east Asia), China (in East-Asia and Pacific), Argentina, Brazil and Uruguay (in Latin America), Puerto Rico (in the Caribbean) and USA and Canada (in North America). Almost of all them have reports of high HIV prevalence in the capital city and other major urban areas.
In 47 countries and territories, estimates of the IDU population were located but no reports of the level of HIV prevalence among them were found. This was the case for 17 countries in North Africa and the Middle-East and sub-Saharan Africa and 12 in Latin America and the Caribbean.
Europe and Central Asia
Eastern Europe and Central Asia
In six countries (Kazakhstan, Poland, Romania, Russia, Ukraine and Uzbekistan) the IDU population exceeded 100 000 and in 12 countries (Belarus, Croatia, Estonia, Kazakhstan, Kyrgyzstan, Latvia, Poland, Romania, Russia, Tajikistan, Turkmenistan and Ukraine) the prevalence of IDU among the adult population was over 0.5% (> 1 in 200 adults aged 15–64 years) (Table 1). Twelve countries have reported HIV prevalence among IDU at under 5%, three (Armenia, Latvia and Poland) have reported levels of infection between 5 and 20%, five (Belarus, Estonia, Kazakhstan, Russia and Ukraine) show levels of HIV above 20% and in the three no information was found.
There can be a wide range of HIV prevalence within a country, with extremely high values confined to specific areas. In Russia, for example, a study undertaken in six cities (Arkhangelsk, Ekateringburg, Irkutsk, Rostov-Don, Samara City and Tver) each with two samples (from needle exchange and drug treatment services), showed that with the exception of Arkhangelsk (at 0.5%) and one of the two sites in Rostov-Don (at 1.3%), the prevalence of HIV among IDU ranged from 10.9 to 64.5% .
In Moscow it was not until 2001 that a high prevalence of HIV infection among IDU was detected. Earlier figures (drawn from drug treatment samples) ranged from 0.12 to 4.9% . In 2001 a study with 60 IDU recruited from drug treatment reported that 28% were HIV positive . Similarly, in St. Petersburg in 1998 two studies reported HIV prevalence at less than 1% [20,21]; 1 year later HIV prevalences of 12%  and 46%  was found; in 2000 a prevalence of 10.9%  to 19.3%  was reported and in 2001 it was 35.7% .
Asia and Pacific
South and South-east Asia
Eight countries in this region (Table 2) have an estimated IDU population greater than 100 000 (Bangladesh, India, Indonesia, Iran, Malaysia, Myanmar, Pakistan, and Viet Nam) and seven have an IDU prevalence among adults greater than 0.5%: Brunei, Indonesia, Iran, Malaysia, Myanmar, Pakistan and Singapore.
Six countries had a reported HIV prevalence among in IDU of less than 5% (Bangladesh, Brunei Darussalam, Laos, Pakistan, Philippines and Singapore), whereas HIV prevalence greater than 20% were found for sites in India, Indonesia, Malaysia, Myanmar, Nepal, Thailand and Viet Nam.
In India the highest HIV prevalence was found in Manipur State at 50 to 81% [23,24]. New Delhi reported a 45% HIV prevalence [25,26], and in Mumbai HIV prevalence was reported as 7.4% in 1998  and 24% in 2000 . Unfortunately, much of the data lacked information on how the figures were derived and were subsequently classified as ‘D'.
East Asia and Pacific
China and Japan have reported IDU populations over 100 000. In Hong Kong and Japan IDU prevalence among the adult population is over 0.5%. HIV prevalence under 5% among IDU was found in Macao and Japan. Reports of HIV prevalence greater than 20% were found for areas in China with estimates of over 70% in Ruili (Yunnan) and Yining (Xianjiang), in Wenshan and Gejiu, (Yunnan), Baise (Guanxi)  and in three cities of Yunnan .
Information on Australia and New Zealand is displayed in Table 2c.
North Africa, Middle East and sub-Saharan Africa
North Africa and the Middle East
Estimates of IDU populations greater than 100 000 were reported for Turkey and Egypt (Table 3). HIV prevalence was 0 to 5% in 10 out of 21 countries and information missing in nine. The highest HIV seroprevalence among IDU was reported for Libya: with one study reporting 0.5% in 1998  and another 59% in 2001 .
Information on IDU populations was found in nine countries. HIV prevalence among IDU was found only for South Africa (2.0% in a study conducted in 1991/2 )
Brazil was the only country with an estimate of the IDU population of over 100 000 and prevalence greater than 0.5% among adults aged 15–64 years (Table 4). In Argentina a population of 50 000 men and 14 500 women cocaine-injectors has been estimated . In Argentina, Brazil and Uruguay there were reports of sites with HIV prevalence greater than 20%. In 10 countries information on HIV prevalence could not be located. Again, the levels of infection are not uniform in a given country. For instance, whereas the national prevalence in Argentina in 2000 was reported as 39.2% (sentinel surveillance results based upon 7 329 patients) , the prevalence for Buenos Aires based on the screening of 600 IDU was 7.6% for 1998–2000 . However, in another study in 2000, based in a hospital in Buenos Aires, a range of 70–80% of seroprevalence was reported .
Estimates for the size of the IDU population were located for three countries and territories. Puerto Rico was the only territory with figures on HIV prevalence among IDU greater than 20%. 
Information on North America is displayed in Table 4c.
We estimate that there are approximately 13.2 million IDU globally. However, this estimate must be treated with great caution as there is great uncertainty surrounding some of the individual country estimates and data were missing for 119 countries and territories.
Information on the size of the IDU population was found for 130 countries and territories and figures for IDU associated HIV for 78. We failed to find any supporting evidence among the sources reviewed (over 300) for 29 of those listed by UNODCCP as having IDU within their frontiers and for 36 having HIV associated with IDU.
Information on the prevalence of HIV among IDU in developing and transitional countries is scarcer than in developed countries. Even when data were available, the strength of evidence was low. It should be noted also, that our assessment of the strength of evidence was based on the type of study used to generate it, but given the difficulties of obtaining representative samples of IDU even the best designed studies need supporting evidence to interpret and corroborate the findings. The strength of evidence for HIV and IDU prevalence estimates in specific cities (data not shown, but available on request) often was greater than any national estimates. Obtaining reliable estimates of the prevalence of IDU through indirect methods that utilize routine data sources tends to be harder, and subject to additional potential biases, at a national than city level . Equally, the best studies of HIV infection among IDU are conducted at city level. We recommend, therefore, that UNAIDS, UNODC, WHO and other agencies consider monitoring IDU and HIV epidemics among IDU in sentinel cities globally.
The amount of information available varied considerably, and did not necessarily correspond with the possible scale of the problem, more to the availability or lack of public health surveillance or monitoring initiatives. Paradoxically, although most of the research on IDU populations or in HIV infection in IDU populations has been conducted in the developed world our collation of estimates suggest that the scale of IDU and of IDU-related HIV infection is far higher in developing and transitional countries. For instance, some East and Southern Asian countries exhibit the highest rates of HIV infection among IDU worldwide. Furthermore, in these countries, IDU represent the most prevalent group among those infected with HIV: by 1999, drug-dependent individuals comprised about 77% of HIV infections in Malaysia and 69% in China, and 66% of AIDS cases in Viet Nam were also drug-dependent people . IDUs account for 82% of all HIV/AIDS cases in Central and Eastern Europe and Former Soviet Union (CEE/FSU) states  and 1.5 million cases of HIV infection have already been reported in this region .
In North Africa and the Middle East, Libya appears to have experienced a rise of HIV among IDU. It is estimated to have about 7 000 drug users, most of whom inject heroin. Almost all of the new HIV infections reported in Libya (564 of 571) during 2000 were among drug users. No country in this region systematically samples and surveys high-risk groups for HIV/AIDS surveillance; instead the general population is represented by low-risk groups such as ante-natal mothers and blood donors. UNAIDS/WHO estimated that approximately 83 000 people were newly infected with HIV in this region in 2002 and that about 0.3% of adults in the region are currently infected.
According to the classification system of epidemic scenarios drawn by UNAIDS/WHO , six of the 18 developing countries with the higher HIV prevalence among IDUs, fit into the category of a generalized epidemic, that is with HIV prevalence consistently > 1% among pregnant women (India, Myanmar, Thailand, Viet Nam, Argentina and Brazil). The other 12 fit into the category of concentrated epidemics (HIV prevalence over 5% in at least one of the defined sub-populations and below 1% among pregnant women in urban areas). However, the diversity of situations observed in this group of countries questions the suitability of this classification system and suggests that while it could be useful for generalized epidemics such those observed in sub-Saharan Africa, perhaps is not the best system to apply to those countries where the epidemic is mainly driven by unsafe injecting practices.
In conclusion, it is obvious from the data collected and assessed in this study that the available information is often of poor quality. It is well known that monitoring risk behaviours in hidden populations is not straightforward. However efforts to improve the accuracy of the information systems should be encouraged. This paper provides a new baseline for estimates on the prevalence of IDU and HIV among IDU that could inform UNAIDS and other international agencies assessment of the global epidemic and breakdown among high-risk groups which was largely missing for IDU in the last report , and the start we hope for reducing the amount of missing information and strengthening the evidence in developing countries.
The Secretariat of the United Nations Reference Group on HIV/AIDS Prevention and Care among IDU in Developing and Transitional Countries (G.V.S., T.R., M.H. and C.A.) is sponsored and funded by the World Health Organization, UNAIDS and United Nations Office on Drugs and Crime. The Centre for Research on Drugs and Health Behaviour is funded through the Department of Health. M.H. is funded on a national career scientist fellowship through the Department of Health.
We are grateful for the support of World Health Organization, UNAIDS and United Nations Office on Drugs and Crime that provided funds for this project. We are greatly indebted to the organisations that generously provided us data. Special thanks go to colleagues in the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), The European Centre for the Epidemiological Monitoring of AIDS, UNODC, WHO, The Saint-Petersburg Pasteur Institute, The Central and Eastern European Harm Reduction Network (CEE-HRN), The Centre for Harm Reduction and the McFarlane Burnet Centre for Medical Research and The Asian Harm Reduction Network. We would also like to express our gratitude to the participants in the UN Reference Group on HIV/AIDS Prevention and Care among IDU in Developing and Transitional Countries for their assistance and to Gema Valencia and Hazel Mann for their technical support.
1. United Nations, Declaration of Commitment on HIV/AIDS
. United Nations General Assembly Special Session on HIV/AIDS. 25–27 June 2001.
2. UNAIDS, Health Canada, The Open Society Institute & The Canadian International Development Agency. The Warsaw Declaration: A Framework for Effective Action on HIV/AIDS and Injecting Drug Use
. Second International Policy Dialogue on HIV/AIDS, Warsaw (Poland), November 12–14, 2003.
3. UNAIDS, Report on the Global HIV/AIDS epidemic
. Geneva: UNAIDS; 2002.
4. UNAIDS, AIDS Epidemic Update
. Geneva: UNAIDS; 2003.
5. UNAIDS/WHO Working group on HIV/AIDS and STI surveillance. Guidelines for Second Generation HIV Surveillance
. Geneva: UNAIDS/WHO. 2000.
6. Morison L. The global epidemiology of HIV/AIDS. Br Med Bull
7. UNAIDS. Follow-up to the 2001 United Nations General Assembly Special Session on HIV/AIDS. Progress Report on the Global Response to the HIV/AIDS Epidemic, 2003
. Geneva: UNAIDS; 2003.
8. UNDP (United Nations Development Programme). Human Development Report 2003. Millennium Development Goals: A Compact among Nations to end Human Poverty.
New York and Oxford: Oxford University Press; 2003.
9. EMCDDA. The State of the Drugs Problem in the European Union and Norway
. Annual report 2003. Lisbon EMCDDA; 2003.
10. EMCDDA. Report on the Drug Situation in the Candidate CEECs
. Lisbon EMCDDA; 2002.
11. EMCDDA. 2002. Annual Report on the State of the Drugs Problem in the European Union and Norway
. Lisbon EMCDDA; 2002.
12. EMCDDA. The State of the Drugs Problem in the Acceding and Candidate Countries to the European Union
. Annual report 2003. Lisbon EMCDDA; 2003.
13. European Centre for the Epidemiological Monitoring of AIDS. EuroHIV, HIV/AIDS Surveillance in Europe
. Mid-year report 2001. No. 65. Saint-Maurice, ECEMA; 2001.
14. US Bureau of the Census, Population Division. International Database [Online] 2004. Available from: http://www.census.gov/ipc/www/idbpyr.html
. US Bureau Census. US Department of Commerce. Washington DC (USA); 2004.
15. Stimson GV, Hickman M, Rhodes T, Bastos F, Saidel T. Methods for assessing HIV and HIV risk, among IDUs and for evaluating interventions. WHO Evidence for Action series – International Journal of Drug Policy, Special issue ‘Evidence for Action on HIV Prevention among Injecting Drug Users'(forthcoming).
16. Hickman M, Taylor C, Chatterjee A, Degenhardt L, Frischer M, Hay G, Tilling K. Estimating drug prevalence: Review of methods with special reference to developing countries. UN Bulletin on Narcotics
2002; LIV (1 and 2).
17. UNODCCP, Global Illicit Drugs Trends. 2001. UNODCCP Studies on Drugs and Crime. Statistics
. New York: UNODCCP; 2001.
18. UNAIDS, WHO & Saint-Petersburg Pasteur Institute, Development, adaptation and field testing of the tools for measuring of biological and behavioural markers used in HIV surveillance in the groups of intravenous drug users in the selected cities of the Russian Federation. The Technical Report. Smolskaya T & Dehne KL (co-ordinators), 2002. Internal report.
19. WHO. Case Study Report - Moscow, Russia. Doljanskaia N (co-ordinator), 2001. Odessa. Internal report.
20. Karapetyan AF, Sokolovsky YV, Araviyskaya ER, Zvartau EE, Ostrovsky DV. Syphilis among intravenous drug-using population: epidemiological situation in St. Petersburg, Russia. Int J STD & AIDS
21. Central and Eastern
European Harm Reduction Network (CEE-HRN), Injecting Drug Users, HIV/AIDS Treatment and Primary Care in Central and Eastern Europe and the Former Soviet Union. Results of a Region-wide Survey.
Vilnius (Lithuania): CEE-HRN; 2002.
22. Smolskaia T, Tretiakova V, Ostrovsky D, Suvoraova S. Ogurtcova S. Three years of experience on HIV control in St. Petersburg (1998–2001) among IDU. XIV International Conference on AIDS
, Barcelona, 2002 [abstract WePeC6119].
23. WHO. Asia Update Critical Issues and Challenges
. Dehne KL (editor): Geneva: 2002. Unpublished document.
24. The Centre for Harm Reduction, McFarlane Burnet Centre for Medical Research & Asian Harm Reduction Network. Manual for Reducing Drug-related Harm in Asia
. Crofts N (editor); Reid G (co-ordinator). Melbourne, Victoria (Australia): Burnet Institute, The Centre for Harm Reduction; 2003.
25. Reid G. Revisiting the Hidden Epidemic. A Situation Assessment of Drug Use in Asia in the Context of HIV/AIDS
. Melbourne, Victoria (Australia): Burnet Institute, The Centre for Harm Reduction; 2002.
26. Dorabjee J, Samson L. A multicentre rapid assessment of injecting drug use
in India. Int J Drug Policy
27. UNAIDS. China's Titanic Peril. 2001 Update of the AIDS Situation and Needs Assessment Report. Geneva: UNAIDS; 2001.
28. UNAIDS, WHO. Epidemiological Fact Sheet on HIV/AIDS and Sexually Transmitted Infections, 2002 update. Libya
. Geneva: UNAIDS, WHO; 2002.
29. Groterah A. Drug Abuse and HIV/AIDS in the Middle East and North Africa. A Situation Assessment
. 2002. Internal document.
30. Williams PG, Ansell SM, Milne FJ. Illicit intravenous drug use in Johannesburg - medical complications and prevalence of HIV infection. S Afr Med J
31. United Nations International Drug Control Programme, Drug abuse prevention with special emphasis on prevention of HIV infection among intravenous drug users (Project no. AD/BRA/94/851). Final project report 1998/1999. Ministry of Health. Internal document.
32. WHO. Background Document No. 10 - Case Study Report - Buenos Aires, Argentina
. 2001. Internal document.
33. Garcia Calleja JM, Walker N, Cuchi P, Lazzari S, Ghys PD. Status of HIV/AIDS epidemic and methods to monitor it in the Latin America
34. Robles RR, Colon HM, Sahai H, Matos TD. Behavioural risk factors and human deficiency virus (HIV) prevalence among intravenous drug users in Puerto Rico. Am J Epidemiol
35. UNODC. Global Assessment Programme on Drug Abuse (GAP) Toolkit Module 2. Estimating Prevalence: Indirect Methods for Estimating the Size of the Drug Problem
. Taylor C, Hickman M (editors): Vienna: UNODC; New York: United Nations; 2003.
36. UNAIDS, UNODC. UNAIDS Asia Pacific Inter-Country Team and UNDCP Regional Centre for East Asia and Pacific. Drug Use and Vulnerability
. Policy Research Study in Asia
. New York: United Nations; 2000.
37. UNAIDS. UNAIDS 2004 Report on the Global HIV/AIDS Epidemic: 4th Global Report. Geneva: UNAIDS; 2004.
Keywords:© 2004 Lippincott Williams & Wilkins, Inc.
injecting drug use; injecting drug use prevalence; HIV seroprevalence; Europe; Eastern; Asia; Latin America; Caribbean; North America; Western Europe; Africa