Potential impact of HIV among IDUs on heterosexual transmission in Asian settings: scenarios from the Asian Epidemic Model

Abstract Introduction : An important public health question is the degree to which HIV epidemics among injecting drug users (IDUs) can contribute to more generalised spread of the virus heterosexually among non-IDUs. Mathematical models can be of use in understanding the complexities of such epidemiological problems. Methods: In this paper, the Asian Epidemic Model (AEM) is used to explore different scenarios for potential HIV transmission by IDUs to non-injecting sexual partners and beyond. The model is applied to a ‘general Asian' setting, in which (1) there is the potential for sex work to drive a self-sustaining heterosexual epidemic, and (2) the vast majority of IDUs are male and do not engage in sex work themselves, but a substantial minority of the IDUs do purchase sexual services from sex workers. Within such a setting, three different scenarios are modeled, and within each scenario, the level of HIV prevalence among IDUs is varied, to see the impact of preventing HIV among IDUs at different stages. Results: The number of HIV infections attributable to IDUs over a 15-year period was greatest when the epidemic among IDUs started in advance of a generalised heterosexual epidemic, with a 171% increase in infections if the IDU prevalence was not kept under control. Once a heterosexual epidemic was underway, controlling HIV prevalence among IDUs still resulted in a meaningful reduction in infections (23%), including among non-IDUs. Once the heterosexual epidemic started to decline, the relative proportion of infections attributable to IDUs increased, creating a situation for IDUs to feed into new epidemics. Discussion: In the early stages of a heterosexual epidemic, maintaining HIV prevalence at low levels among IDUs can buy critical time to address the potential for rapid heterosexual transmission. In more advanced heterosexual epidemics, preventing HIV among IDUs can still avert a substantial number of infections.

[1]  Modelling.  Improved methods and assumptions for estimation of the HIV/AIDS epidemic and its impact: Recommendations of the UNAIDS Reference Group on Estimates, Modelling and Projections. , 2002, AIDS.

[2]  Kong‐lai Zhang,et al.  Epidemiology of HIV in China , 2002, BMJ : British Medical Journal.

[3]  E H Kaplan,et al.  A model-based estimate of HIV infectivity via needle sharing. , 1992, Journal of acquired immune deficiency syndromes.

[4]  C. Luo,et al.  HIV type 1 in Thailand, 1994-1995: persistence of two subtypes with low genetic diversity. , 1998, AIDS research and human retroviruses.

[5]  Roy M. Anderson,et al.  Transmission dynamics of HIV infection , 1987, Nature.

[6]  J. Mullins,et al.  Determination of HIV‐1 subtypes in injecting drug users in Bangkok, Thailand, using peptide‐binding enzyme immunoassay, and heteroduplex mobility assay: evidence of increasing infection with HIV‐1 subtype E , 1995, AIDS.

[7]  D. D. Des Jarlais,et al.  Maintaining low HIV seroprevalence in populations of injecting drug users. , 1995, JAMA.

[8]  R. Detels,et al.  HIV-1 subtypes in injecting drug users & their non-injecting wives in Manipur, India. , 2000, The Indian journal of medical research.

[9]  G. Stimson,et al.  Drug injecting and HIV infection : global dimensions and local responses , 1998 .

[10]  J. Kaewkungwal,et al.  HIV‐1 incidence determined retrospectively among drug users in Bangkok, Thailand , 1994, AIDS.

[11]  Samson,et al.  A multi-centre rapid assessment of injecting drug use in India. , 2000, The International journal on drug policy.

[12]  R. Detels,et al.  Transmission of HIV from injecting drug users to their wives in India , 2000, International journal of STD & AIDS.

[13]  C. Venkataramana,et al.  Extent and speed of spread of HIV infection in India through the commercial sex networks: a perspective , 2001, Tropical medicine & international health : TM & IH.

[14]  A. Lansky,et al.  A method for classification of HIV exposure category for women without HIV risk information. , 2001, MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports.

[15]  K. Ungchusak,et al.  The epidemiology of HIV infection and AIDS in Thailand. , 1991, AIDS.

[16]  D. D. Des Jarlais,et al.  Fifteen years of research on preventing HIV infection among injecting drug users: what we have learned, what we have not learned, what we have done, what we have not done. , 1998, Public health reports.

[17]  S. Pal,et al.  Intravenous drug users--a new high-risk group for HIV infection in India. , 1991, AIDS.

[18]  J. Esparza,et al.  Continued high HIV-1 incidence in a vaccine trial preparatory cohort of injection drug users in Bangkok, Thailand , 2001, AIDS.

[19]  A. Divekar,et al.  Disease prevalence in women attending the STD clinic in Mumbai (formerly Bombay), India , 2000, International journal of STD & AIDS.

[20]  A. Ball,et al.  HIV prevention among injecting drug users: responses in developing and transitional countries. , 1998, Public health reports.

[21]  G. Stimson.  AIDS and injecting drug use in the United Kingdom, 1987-1993: the policy response and the prevention of the epidemic. , 1995, Social science & medicine.

[22]  H. Gayle,et al.  Independent introduction of two major HIV-1 genotypes into distinct high-risk populations in Thailand , 1993, The Lancet.