Background The spectrum of sexual practices that transmit Neisseria gonorrhoeae in men who have sex with men (MSM) is controversial. No studies have modelled potential Neisseria gonorrhoeae transmission when one sexual practice follows another in the same sexual encounter (‘sequential sexual practices’). Our aim was to test what sequential practices were necessary to replicate the high proportion of MSM who have more than one anatomical site infected with gonorrhoea (‘multisite infection’).
Methods To test our aim, we developed eight compartmental models. We first used a baseline model (model 1) that included no sequential sexual practices. We then added three possible sequential transmission routes to model 1: (1) oral sex followed by anal sex (or vice versa) (model 2); (2) using saliva as a lubricant for penile–anal sex (model 3) and (3) oral sex followed by oral–anal sex (rimming) or vice versa (model 4). The next four models (models 5–8) used combinations of the three transmission routes.
Results The baseline model could only replicate infection at the single anatomical site and underestimated multisite infection. When we added the three transmission routes to the baseline model, oral sex, followed by anal sex or vice versa, could replicate the prevalence of multisite infection. The other two transmission routes alone or together could not replicate multisite infection without the inclusion of oral sex followed by anal sex or vice versa.
Conclusions Our gonorrhoea model suggests sexual practices that involve oral followed by anal sex (or vice versa) may be important for explaining the high proportion of multisite infection.
- gay men
- incidence studies
- sexual behaviour
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Handling editor Laith J Abu-Raddad
Twitter @EricPFChow, @drdebwilliamson
Contributors XX, LZ and CKF conceived and designed the study; XX and LZ established the model; XX and LZ did the analysis; MS contributed in checking the analysis and gave overall feedback to the analysis; XX wrote the first draft; CKF provided critical insights for framing of the first draft; EPFC, JJO, CJPAH, DB, MS, FYSK, JSH, CKF and LZ revised the manuscript. All authors reviewed drafts and approved the final manuscript.
Funding EPFC, DW and CKF are supported by an Australian National Health and Medical Research Council (NHMRC) Emerging Leadership Investigator Grant (GNT1172873, GNT1174555 and GNT1172900, respectively). JJO is supported by an Australian NHMRC early career fellowship (APP1104781). MS was supported by the National Natural Science Foundation of China (grant number:11 801 435 (MS)), China Postdoctoral Science Foundation (grant number 2018M631134M631134), the Fundamental Research Funds for the Central Universities (grant number: xjh012019055, xzy032020026) and Natural Science Basic Research ProgramProgram of Shaanxi Province (Grant number: 2019JQ-187). LZ is supported by the National Natural Science Foundation of China (Grant number: 81950410639); Outstanding Young Scholars Support Program (Grant number: 3111500001); Xi’an Jiaotong University Basic Research and Profession Grant (Grant number: xtr022019003, xzy032020032); Epidemiology modeling and risk assessment (Grant number: 20200344) and Xi’an Jiaotong University Young Scholar Support Grant (Grant number: YX6J004).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study used secondary data analysis of datasets obtained from previous publications and therefore ethical approval was not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. The data were all collected from published articles and reports. Data are available in the supplementary materials.