title: Oral and anal sex are key to sustaining gonorrhoea at endemic levels in MSM populations: a mathematical model.
abstract: OBJECTIVE
  Despite early treatment of urethral infection, gonorrhoea is endemic in urban populations of men who have sex with men (MSM) in Australia. By contrast, gonorrhoea is not common in urban heterosexual populations. Sexual activities among MSM usually involve anal or oral sex, and as these behaviours are becoming increasingly common among heterosexuals, there is a need to investigate their roles in transmission of gonorrhoea.
  
  
  METHODS
  We developed individual-based models of transmission of gonorrhoea in MSM and heterosexuals that incorporate anatomical site-specific transmission of gonorrhoea. We estimated the probabilities of transmission for anal sex and oral sex by calibrating an MSM model against prevalence of gonorrhoea and sexual activity data. These probabilities were then applied to a heterosexual model in order to examine whether gonorrhoea can persist in a heterosexual population through the addition of anal sex and oral sex.
  
  
  RESULTS
  In the MSM model, gonorrhoea can persist despite prompt treatment of urethral infections. The probability of gonorrhoea persisting is reduced if use of condom for oral sex is increased to more than 15% of acts. Assuming that treatment of symptomatic infections is prompt, gonorrhoea is unlikely to persist in a heterosexual population even with the addition of anal and oral sex.
  
  
  CONCLUSIONS
  Our models suggest that oral sex has an important role in sustaining gonorrhoea in a population of MSM by providing a pool of untreated asymptomatic infection. The importance of anal sex or oral sex in sustaining gonorrhoea in a heterosexual population remains uncertain due to the lack of information linking different types of sex acts and transmissibility.
authors.affiliation: The Kirby Institute, UNSW Australia, Sydney, Australia.
authors.forename: B
authors.initials: B
authors.lastname: Hui
authors.affiliation: School of Population and Global Health, University of Melbourne, Melbourne, Australia Melbourne Sexual Health Centre, Alfred Health, Melbourne, Australia Australian Research Centre in Sex, Health and Society, La Trobe University, Melbourne, Australia.
authors.forename: C K
authors.initials: CK
authors.lastname: Fairley
authors.affiliation: School of Population and Global Health, University of Melbourne, Melbourne, Australia Melbourne Sexual Health Centre, Alfred Health, Melbourne, Australia Australian Research Centre in Sex, Health and Society, La Trobe University, Melbourne, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.affiliation: The Kirby Institute, UNSW Australia, Sydney, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Grulich
authors.affiliation: Centre for Women's Health, Gender and Society, University of Melbourne, Melbourne, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Hocking
authors.affiliation: The Kirby Institute, UNSW Australia, Sydney, Australia Australian Research Centre in Sex, Health and Society, La Trobe University, Melbourne, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Prestage
authors.affiliation: Melbourne Sexual Health Centre, Alfred Health, Melbourne, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Walker
authors.affiliation: The Kirby Institute, UNSW Australia, Sydney, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Law
authors.affiliation: The Kirby Institute, UNSW Australia, Sydney, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Regan
mesh_terms: D000328:Adult; D001315:Australia / Q000453:epidemiology; D017280:Condoms / Q000706:statistics & numerical data*; D006069:Gonorrhea / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D007722:Health Knowledge, Attitudes, Practice; D018451:Homosexuality, Male / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D010614:Pharynx / Q000821:virology*; D015995:Prevalence; D012007:Rectum / Q000821:virology*; D012307:Risk Factors; D012725:Sexual Behavior; D012747:Sexual Partners; D014505:Urban Population
keywords: GAY MEN; GONORRHOEA; MODELING; ORAL SEX