Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A dynamic network model to disentangle the roles of steady and casual partners for HIV transmission among MSM
Stockholm University, Faculty of Science, Department of Mathematics.
Stockholm University, Faculty of Science, Department of Mathematics.
Stockholm University, Faculty of Science, Department of Mathematics.
Number of Authors: 42019 (English)In: Epidemics, ISSN 1755-4365, E-ISSN 1878-0067, Vol. 27, p. 66-76Article in journal (Refereed) Published
Abstract [en]

HIV is a sexually transmitted infection (STI) whose transmission process is highly dependent on the sexual network structure of the population under consideration. Most sexual behaviour data is egocentric in nature. We develop a stochastic dynamic sexual network model that utilises this type of egocentric network data. The model incorporates both steady and casual sex partners, and can be seen as a stochastic form of a generalised pair-formation model. We model the spread of an infection where individuals are susceptible, infectious, or successfully treated (and unable to transmit) and derive analytical expressions for several epidemiological quantities. We use sexual behaviour and HIV prevalence data that was gathered among 403 MSM at an STI clinic in Stockholm. To accurately capture transmission dynamics for this population, we need to explicitly model both casual sex partners and steady partnerships. Our model yields an estimate for the mean time until diagnosis followed by successful treatment that is in line with literature. This study indicates that small reductions in the time to diagnosis, and thereby, beginning of treatment, may substantially reduce HIV prevalence. Moreover, we find that moderate increases in condom use with casual sex partners have greater impact on reducing prevalence than the same increases in condom use with steady sex partners. This result demonstrates the relative importance of casual contacts on the HIV transmission dynamics among MSM in Sweden. Our results highlight the importance of HIV testing and condom-use interventions, and the role that casual and steady partners play in this, in order to turn the epidemiological trend in Sweden towards decreased HIV incidence.

Place, publisher, year, edition, pages
2019. Vol. 27, p. 66-76
Keywords [en]
Mathematical models, Dynamic networks, Sexual behaviour, HIV, Steady and casual partners
National Category
Infectious Medicine Mathematics
Research subject
Mathematical Statistics
Identifiers
URN: urn:nbn:se:su:diva-170112DOI: 10.1016/j.epidem.2019.02.001ISI: 000469416700008PubMedID: 30738786OAI: oai:DiVA.org:su-170112DiVA, id: diva2:1333623
Available from: 2019-07-01 Created: 2019-07-01 Last updated: 2019-10-07Bibliographically approved
In thesis
1. Modelling Sexual Interactions: Sexual behaviour and the spread of sexually transmitted infections on dynamic networks
Open this publication in new window or tab >>Modelling Sexual Interactions: Sexual behaviour and the spread of sexually transmitted infections on dynamic networks
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis we develop statistical and mathematical models to study different factors of relevance for the spread of sexually transmitted infections (STIs). Two special interest groups for STI interventions are considered: sexually active youths and men who have sex with men (MSM). The statistical models developed make it possible to estimate individuals’ dispositions towards sexual behaviours related to the spread of STIs: condom use and anal sex. To study the spread of an infection in a population we use mathematical models. The mathematical models in this thesis give insights into the transmission process of HIV among MSM in Sweden—a population at high risk for HIV infection.

The focus of the first paper is on mechanisms giving rise to observed sexual behaviour, such as condom use, among sexually active youths in Sweden. We study the sexual dispositions of individuals and how these interact and generate the observed sexual outcomes.

The second paper concerns the sexual behaviour of MSM in Sweden and the transmission process of HIV within this population. The population is modelled by a stochastic dynamic network model that incorporates both steady partnerships and casual contacts. We model the spread of an infection where individuals are susceptible, infectious or diagnosed (unable to transmit) and derive the basic reproduction number R0, the probability of a major outbreak, and the endemic prevalence.

The third paper further develops the dynamic network model of the second paper. The model now takes into account that individuals may be sexually high-active or sexually low-active. The division into two activity groups makes it possible to study a preventive intervention against HIV that is only targeted to sexually high-active. The intervention studied is pre-exposure prophylaxis for HIV (PrEP), i.e. that the antiviral drugs tenofovir-emtricitabine are taken by individuals with negative HIV serostatus to prevent getting infected by HIV. We study the PrEP coverage needed to reduce the observed HIV prevalence of 5% to a value close to 0%.

In the fourth and final paper we focus on condom dispositions among MSM. The disposition models from the first paper are extended to better fit an MSM population and are additionally extended to be used for more types of sexual behaviour data.

Place, publisher, year, edition, pages
Stockholm: Department of Mathematics, Stockholm University, 2019. p. 40
Keywords
Mathematical modelling, Sexually transmitted infections, Egocentric network analysis, Dynamic networks, Sexual behaviour, HIV, Statistical inference
National Category
Probability Theory and Statistics
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:su:diva-172941 (URN)978-91-7797-857-2 (ISBN)978-91-7797-858-9 (ISBN)
Public defence
2019-11-28, sal 14, hus 5, Kräftriket, Roslagsvägen 101, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2019-11-05 Created: 2019-09-16 Last updated: 2019-10-22Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Hansson, DisaLeung, KaYinBritton, Tom
By organisation
Department of Mathematics
In the same journal
Epidemics
Infectious MedicineMathematics

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 285 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf