Who mixes with whom among men who have sex with men? Implications for modelling the HIV epidemic in southern India

K M Mitchell, A M Foss, H J Prudden, Z Mukandavire, M Pickles, J R Williams, H C Johnson, B M Ramesh, R Washington, S Isac, S Rajaram, A E Phillips, J Bradley, M Alary, S Moses, C M Lowndes, C H Watts, M-C Boily, P Vickerman

Research output: Contribution to journalArticle

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Abstract

In India, the identity of men who have sex with men (MSM) is closely related to the role taken in anal sex (insertive, receptive or both), but little is known about sexual mixing between identity groups. Both role segregation (taking only the insertive or receptive role) and the extent of assortative (within-group) mixing are known to affect HIV epidemic size in other settings and populations. This study explores how different possible mixing scenarios, consistent with behavioural data collected in Bangalore, south India, affect both the HIV epidemic, and the impact of a targeted intervention. Deterministic models describing HIV transmission between three MSM identity groups (mostly insertive Panthis/Bisexuals, mostly receptive Kothis/Hijras and versatile Double Deckers), were parameterised with behavioural data from Bangalore. We extended previous models of MSM role segregation to allow each of the identity groups to have both insertive and receptive acts, in differing ratios, in line with field data. The models were used to explore four different mixing scenarios ranging from assortative (maximising within-group mixing) to disassortative (minimising within-group mixing). A simple model was used to obtain insights into the relationship between the degree of within-group mixing, R0 and equilibrium HIV prevalence under different mixing scenarios. A more complex, extended version of the model was used to compare the predicted HIV prevalence trends and impact of an HIV intervention when fitted to data from Bangalore. With the simple model, mixing scenarios with increased amounts of assortative (within-group) mixing tended to give rise to a higher R0 and increased the likelihood that an epidemic would occur. When the complex model was fit to HIV prevalence data, large differences in the level of assortative mixing were seen between the fits identified using different mixing scenarios, but little difference was projected in future HIV prevalence trends. An oral pre-exposure prophylaxis (PrEP) intervention was modelled, targeted at the different identity groups. For intervention strategies targeting the receptive or receptive and versatile MSM together, the overall impact was very similar for different mixing patterns. However, for PrEP scenarios targeting insertive or versatile MSM alone, the overall impact varied considerably for different mixing scenarios; more impact was achieved with greater levels of disassortative mixing.

Original languageEnglish
Pages (from-to)140-50
Number of pages11
JournalJournal of Theoretical Biology
Volume355
Early online date13 Apr 2014
DOIs
Publication statusPublished - 21 Aug 2014
Externally publishedYes

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India
HIV
gender
Modeling
Marginal Structural Models
Scenarios
Segregation
Sexual Behavior
disease control
Model
Large Data
Deterministic Model
Population
mouth
Likelihood

Keywords

  • HIV Infections
  • HIV-1
  • Homosexuality, Male
  • Humans
  • India
  • Male
  • Models, Biological
  • Prevalence
  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Mathematical model
  • Mixing matrix
  • Sexually transmitted infection
  • Disassortative mixing
  • Pre-exposure prophylaxis

Cite this

Who mixes with whom among men who have sex with men? Implications for modelling the HIV epidemic in southern India. / Mitchell, K M; Foss, A M; Prudden, H J; Mukandavire, Z; Pickles, M; Williams, J R; Johnson, H C; Ramesh, B M; Washington, R; Isac, S; Rajaram, S; Phillips, A E; Bradley, J; Alary, M; Moses, S; Lowndes, C M; Watts, C H; Boily, M-C; Vickerman, P.

In: Journal of Theoretical Biology, Vol. 355, 21.08.2014, p. 140-50.

Research output: Contribution to journalArticle

Mitchell, KM, Foss, AM, Prudden, HJ, Mukandavire, Z, Pickles, M, Williams, JR, Johnson, HC, Ramesh, BM, Washington, R, Isac, S, Rajaram, S, Phillips, AE, Bradley, J, Alary, M, Moses, S, Lowndes, CM, Watts, CH, Boily, M-C & Vickerman, P 2014, 'Who mixes with whom among men who have sex with men? Implications for modelling the HIV epidemic in southern India' Journal of Theoretical Biology, vol. 355, pp. 140-50. https://doi.org/10.1016/j.jtbi.2014.04.005
Mitchell, K M ; Foss, A M ; Prudden, H J ; Mukandavire, Z ; Pickles, M ; Williams, J R ; Johnson, H C ; Ramesh, B M ; Washington, R ; Isac, S ; Rajaram, S ; Phillips, A E ; Bradley, J ; Alary, M ; Moses, S ; Lowndes, C M ; Watts, C H ; Boily, M-C ; Vickerman, P. / Who mixes with whom among men who have sex with men? Implications for modelling the HIV epidemic in southern India. In: Journal of Theoretical Biology. 2014 ; Vol. 355. pp. 140-50.
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AU - Mukandavire, Z

AU - Pickles, M

AU - Williams, J R

AU - Johnson, H C

AU - Ramesh, B M

AU - Washington, R

AU - Isac, S

AU - Rajaram, S

AU - Phillips, A E

AU - Bradley, J

AU - Alary, M

AU - Moses, S

AU - Lowndes, C M

AU - Watts, C H

AU - Boily, M-C

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N2 - In India, the identity of men who have sex with men (MSM) is closely related to the role taken in anal sex (insertive, receptive or both), but little is known about sexual mixing between identity groups. Both role segregation (taking only the insertive or receptive role) and the extent of assortative (within-group) mixing are known to affect HIV epidemic size in other settings and populations. This study explores how different possible mixing scenarios, consistent with behavioural data collected in Bangalore, south India, affect both the HIV epidemic, and the impact of a targeted intervention. Deterministic models describing HIV transmission between three MSM identity groups (mostly insertive Panthis/Bisexuals, mostly receptive Kothis/Hijras and versatile Double Deckers), were parameterised with behavioural data from Bangalore. We extended previous models of MSM role segregation to allow each of the identity groups to have both insertive and receptive acts, in differing ratios, in line with field data. The models were used to explore four different mixing scenarios ranging from assortative (maximising within-group mixing) to disassortative (minimising within-group mixing). A simple model was used to obtain insights into the relationship between the degree of within-group mixing, R0 and equilibrium HIV prevalence under different mixing scenarios. A more complex, extended version of the model was used to compare the predicted HIV prevalence trends and impact of an HIV intervention when fitted to data from Bangalore. With the simple model, mixing scenarios with increased amounts of assortative (within-group) mixing tended to give rise to a higher R0 and increased the likelihood that an epidemic would occur. When the complex model was fit to HIV prevalence data, large differences in the level of assortative mixing were seen between the fits identified using different mixing scenarios, but little difference was projected in future HIV prevalence trends. An oral pre-exposure prophylaxis (PrEP) intervention was modelled, targeted at the different identity groups. For intervention strategies targeting the receptive or receptive and versatile MSM together, the overall impact was very similar for different mixing patterns. However, for PrEP scenarios targeting insertive or versatile MSM alone, the overall impact varied considerably for different mixing scenarios; more impact was achieved with greater levels of disassortative mixing.

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KW - HIV Infections

KW - HIV-1

KW - Homosexuality, Male

KW - Humans

KW - India

KW - Male

KW - Models, Biological

KW - Prevalence

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

KW - Mathematical model

KW - Mixing matrix

KW - Sexually transmitted infection

KW - Disassortative mixing

KW - Pre-exposure prophylaxis

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JO - Journal of Theoretical Biology

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