Using mathematical modelling to help explain the differential increase in HIV incidence in New South Wales, Victoria and Queensland: importance of other sexually transmissible infections
Alexander Hoare A , David P. Wilson A B , David G. Regan A , John Kaldor A and Matthew G. Law AA National Centre in HIV Epidemiology and Clinical Research, Faculty of Medicine, University of New South Wales, Level 2, 376 Victoria Street, Sydney, NSW 2010, Australia.
B Corresponding author. Email: dwilson@nchecr.unsw.edu.au
Sexual Health 5(2) 169-187 https://doi.org/10.1071/SH07099
Submitted: 17 December 2007 Accepted: 16 April 2008 Published: 2 June 2008
Abstract
Background: Since 1999 there has been an increase in the number of HIV diagnoses in Australia, predominantly among men who have sex with men (MSM), but the magnitude of increase differs between states: ~7% rise in New South Wales, ~96% rise in Victoria, and ~68% rise in Queensland. Methods: Epidemiological, clinical, behavioural and biological data were collated into a mechanistic mathematical model to explore possible reasons for this increase in HIV notifications in MSM. The model was then used to make projections to 2015 under various scenarios. Results: The model suggests that trends in clinical and behavioural parameters, including increases in unprotected anal intercourse, cannot explain the magnitude of the observed rise in HIV notifications, without a substantial increase in a ‘transmission-increasing’ factor. We suggest that a highly plausible biological factor is an increase in the prevalence of other sexually transmissible infections (STI). It was found that New South Wales required an ~2-fold increase in other STI to match the data, Victoria needed an ~11-fold increase, and Queensland required an ~9-fold increase. This is consistent with observed trends in Australia for some STI in recent years. Future projections also indicate that the best way to control the current rise in HIV notifications is to reduce the prevalence of other STI and to promote condom use, testing for HIV, and initiation of early treatment in MSM diagnosed during primary infection. Conclusions: Our model can explain the recent rise in HIV notifications with an increase in the prevalence of other STI. This analysis highlights that further investigation into the causes and impact of other STI is warranted in Australia, particularly in Victoria.
Additional keywords: Australia, men who have sex with men.
Acknowledgements
The authors thank the members of the Reference Group that provided advice and guidance through the development of this report. Members of the Reference Group, and the bodies they represented, were: Professor Frank Bowden, HIV/AIDS and STI Subcommittee of the Ministerial Advisory Committee on AIDS, Sexual Health and Hepatitis; Ms Sharon Flanagan and Ms Karen Fox, Australian Government Department of Health and Ageing; Associate Professor John Imrie, National Centre in HIV Social Research, University of New South Wales; Mr Philip Keen, AIDS Council of New South Wales; Dr Rosemary Lester, Communicable Diseases Network Australia; Dr Kelly Shaw, Blood Borne Virus Surveillance System; and Mr Bill Whittaker, National Association of People living With HIV/AIDS. The authors also thank the following colleagues and collaborators at the National Centre in HIV Epidemiology and Clinical Research for making data available, and also for numerous discussions and advice on interpretation: Dr Handan Wand, Ms Linda Gelgor, Ms Kathleen Falster, Professor Andrew Grulich, Associate Professor Anthony Kelleher, Ms Ann McDonald, Ms Melanie Middleton and Dr Garrett Prestage. The National Centre in HIV Epidemiology and Clinical Research is funded by the Australian Government Department of Health and Ageing, and is affiliated with the Faculty of Medicine, University of New South Wales. Dr David Wilson is funded by a Vice Chancellor’s Fellowship from the University of New South Wales and by grant number DP0771620 from the Australian Research Council; Mr Alex Hoare is funded by a University Postgraduate Award from the University of New South Wales; Dr David Regan is funded by grant number 358425 from the Australian National Health and Medical Research Council; Associate Professor Matthew Law is funded by grant numbers 1-U01-AI6994-01, 1-U01-AI068641, 1-U01-A1069907-01 and 5-U19-AI05371 from the National Institutes of Health, USA.
[1]
[2]
[3] Quinn TC, Wawer MJ, Sewankambo N, Serwadda D, Li C, Wabwire-Mangen F, et al. Viral load and heterosexual transmission of human immunodeficiency virus type 1. N Engl J Med 2000; 342 921–9.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[4] Falster K, Gelgor L, Shaik A, Zablotska I, Prestage G, Grierson J, et al. HIV antiretroviral treatment differences by state in Australia. Sex Health 2007; 5 141–54.
| Crossref | GoogleScholarGoogle Scholar |
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] Grulich AE, Cunningham P, Munier M-L, Prestage G, Amin J, Ringland C, et al. Sexual behaviour and human herpesvirus infection in homosexual men in Australia. Sex Health 2005; 2 13–8.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[13] Jin F, Prestage GP, Kippax SC, Pell CM, Donovan BJ, Kaldor JM, et al. Epidemic syphilis among homosexually active men in Sydney. Med J Aust 2005; 183 179–83.
| PubMed |
[14]
[15] Mao L, Crawford JM, Hospers HJ, Prestage GP, Grulich AE, Kaldor J, et al. ‘Serosorting’ in casual anal sex of HIV-negative gay men is noteworthy and is increasing in Sydney, Australia. AIDS 2006; 20 1204–6.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[16] Cleary PD, Van Devanter N, Rogers TF, Singer E, Shipton-Lery R, Steilen M, et al. Behavior changes after notification of HIV infection. Am J Public Health 1991; 81 1586–90.
| PubMed |
[17] Colfax GN, Buchbinder SP, Cornelisse PGA, Vittinghoff E, Mayer K, Celum C, et al. Sexual risk behaviors and implications for secondary HIV transmission during and after HIV seroconversion. AIDS 2002; 16 1529–35.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[18] Marks G, Crepaz N, Senterfitt JW, Janssen RS. Meta-analysis of high-risk sexual behavior in persons aware and unaware they are infected with HIV in the United States: implications for HIV prevention programs. J Acquir Immune Defic Syndr 2005; 39 446–53.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[19] McCusker J, Stoddard AM, Mayer KH, Zapka J, Morrison C, Saltzman SP, et al. Effects of HIV antibody test knowledge on subsequent sexual behaviors in a cohort of homosexually active men. Am J Public Health 1988; 78 462–7.
| PubMed |
[20] Saah AJ, Hoover DR, Weng S, Carrington M, Mellors J, Rinaldo CR Jr, et al. Association of HLA profiles with early plasma viral load, CD4+ cell count and rate of progression to AIDS following acute HIV-1 infection. Multicenter AIDS Cohort Study. AIDS 1998; 12 2107–13.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[21] Smith DK, Warren DL, Valhov D, Schuman P, Stein MD, Greenberg BL, et al. Design and baseline participant characteristics of the Human Immunodeficiency Virus Epidemiology Research (HER) Study: a prospective cohort study of human immunodeficiency virus infection in US women. Am J Epidemiol 1997; 146 459–69.
| PubMed |
[22] Valleroy LA, MacKellar DA, Karon JM, Rosen DH, McFarland W, Shehan DA, et al. HIV prevalence and associated risks in young men who have sex with men. Young Men’s Survey Study Group. JAMA 2000; 284 198–204.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[23] Van de Ven P, Mao L, Fogarty A, Rawstorne P, Crawford J, Prestage G, et al. Undetectable viral load is associated with sexual risk taking in HIV serodiscordant gay couples in Sydney. AIDS 2005; 19 179–84.
| PubMed |
[24] Crawford JM, Kippax SC, Mao L, Van de Ven PG, Prestage GP, Grulich AE, et al. Number of risk acts by relationship status and partner serostatus: findings from the HIM cohort of homosexually active men in Sydney, Australia. AIDS Behav 2006; 10 325–31.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[25] Bautista CT, Sanchez JL, Montano SM, Laguna-Torres VA, Lama JR, Sanchez JL, et al. Seroprevalence of and risk factors for HIV-1 infection among South American men who have sex with men. Sex Transm Infect 2004; 80 498–504.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[26] Fleming DT, Wasserheit JN. From epidemiological synergy to public health policy and practice: the contribution of other sexually transmitted diseases to sexual transmission of HIV infection. Sex Transm Infect 1999; 75 3–17.
| PubMed |
[27] Galvin SR, Cohen MS. The role of sexually transmitted diseases in HIV transmission. Nat Rev Microbiol 2004; 2 33–42.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[28] Piot P, Laga M. Genital ulcers, other sexually transmitted diseases, and the sexual transmission of HIV. BMJ 1989; 298 623–4.
| PubMed |
[29] Read TRH, Hocking J, Sinnott V, Hellard M. Rick factors for incident HIV infection in men having sex with men: a case-control study. Sex Health 2007; 4 35–9.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[30] Rottingen JA, Cameron DW, Garnett GP. A systematic review of the epidemiologic interactions between classic sexually transmitted diseases and HIV: how much really is known? Sex Transm Dis 2001; 28 579–97.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
[31] Simonsen JN, Cameron DW, Gakinya MN, Ndinya-Achola JO, D’Costa LJ, Karasira P, et al. Human immunodeficiency virus infection among men with sexually transmitted diseases. Experience from a center in Africa. N Engl J Med 1988; 319 274–8.
[32] Middleton MG, McDonald AM, Grulich AE, Donovan B, Kaldor JM. Could sexually transmissible infections be contributing to the increase in HIV infections among men who have sex with men in Australia? Sex Health 2008; 5 131–40.
| Crossref | GoogleScholarGoogle Scholar |
[33] Blower SM, Dowlatabadi H. Sensitivity and uncertainty analysis of complex models of disease transmission: an HIV model, as an example. Int Stat Rev 1994; 62 229–43.
[34] Hoare A, Regan DG, Wilson DP. Sampling and sensitivity analyses tools (SaSAT) for computational modelling. Theor Biol Med Model 2008; 5 4.
| Crossref | GoogleScholarGoogle Scholar |
[35] Bonjoch A, Paredes R, Domingo P, Cervantes M, Pedrol E, Ribera E, et al. Long-term safety and efficacy of nevirapine-based approaches in HIV type 1-infected patients. AIDS Res Hum Retroviruses 2006; 22 321–9.
| Crossref | GoogleScholarGoogle Scholar |
[36] Rangsin R, Chiu J, Khamboonruang C, Sirisopana N, Eiumtrakul S, Brown AE, et al. The natural history of HIV-1 infection in young Thai men after seroconversion. J Acquir Immune Defic Syndr 2004; 36 622–9.
| Crossref | GoogleScholarGoogle Scholar |
[37] Richardson BA, Mbori-Ngacha D, Lavreys L, John-Stewart GC, Nduati R, Panteleeff DD, et al. Comparison of human immunodeficiency virus type 1 viral loads in Kenyan women, men, and infants during primary and early infection. J Virol 2003; 77 7120–3.
| Crossref | GoogleScholarGoogle Scholar |
[38] Sabin CA, Devereux H, Phillips AN, Hill A, Janossy G, Lee CA, et al. Course of viral load throughout HIV-1 infection. J Acquir Immune Defic Syndr 2000; 23 172–7.
[39] Simon V, Ho DD, Abdool Karim Q. HIV/AIDS epidemiology, pathogenesis, prevention, and treatment. Lancet 2006; 368 489–504.
| Crossref | GoogleScholarGoogle Scholar |
[40] Yozviak JL, Doerfler RE, Woodward WC. Effectiveness and tolerability of nevirapine, stavudine, and lamivudine in clinical practice. HIV Clin Trials 2001; 2 474–6.
| Crossref | GoogleScholarGoogle Scholar |
[41] Zablotska I, Prestage G, Grulich AE, Imrie J. Differing trends in sexual risk behaviours in three Australian states: New South Wales, Victoria and Queensland, 1998–2006. Sex Health 2008; 5 125–30.
| Crossref | GoogleScholarGoogle Scholar |
[42]
[43] Zhang H, Dornadula G, Beumont M, Livornese L, Van Uitert B, Henning K, et al. Human immunodeficiency virus type 1 in the semen of men receiving highly active antiretroviral therapy. N Engl J Med 1998; 339 1803–9.
| Crossref | GoogleScholarGoogle Scholar |
