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Epidemiology poster session 2: Population: Men who have sex with men
P1-S2.57 Using an online survey to investigate risk behaviours and social networks in a syphilis outbreak among men who have sex with men in Toronto
  1. R Shahin1,
  2. C Rank2,
  3. B Kinniburgh2,
  4. A Jolly2,
  5. D Al-Bargash1,
  6. B Clarke1,
  7. M Ofner2,
  8. M L Gilbert2
  1. 1Toronto Public Health, Toronto Canada
  2. 2Public Health Agency of Canada, Ottawa, Canada


Background An outbreak of infectious syphilis among men who have sex with men (MSM) in Toronto began in 2002 and peaked in 2009 when 579 cases were reported. We developed an internet-based enhanced surveillance tool to investigate HIV coinfection, sexual risk behaviours, and social networks among a sample of cases in 2010.

Methods Males with infectious syphilis in Toronto from 15 April 2010 to 30 June 2010 were invited to complete a self-administered online survey. Data were collected on sexual partners, risk behaviours, condom use, and venues where respondents looked for sex partners in the 6 months before syphilis infection. We assessed key survey variables by HIV status, and carried out social network analyses to examine links between cases, sexual contacts and venues.

Results Of 84 eligible cases, 46 were successfully contacted and 27 completed the survey. Three of 27 respondents (11%) identified sexual contacts and 16 (59%) reported having multiple sex partners during routine case follow-up. In the online survey, almost all men (n=26) reported at least one male sex partner in the six months before syphilis infection (median 5 partners; IQR 2–12). HIV prevalence among respondents was 70% (vs 35% among non-respondents, p<0.01). Predominant risk behaviours were anonymous sex (64%), group sex (56%), and 55% indicated participation in barebacking (63% of HIV-positive and 33% of HIV-negative men). Of 19 HIV-positive respondents, 17 (89%) had at least one HIV-positive partner; condom use with HIV-positive partners was low (16% and 28% used condoms all or most times during receptive and insertive anal sex, respectively). Among 25 cases who provided information on venues where they looked for sex partners, most sought partners online (88%), at bathhouses (60%) or bars (36%); 22 cases were linked by six common venues—three websites, two bathhouses and one bar.

Conclusions A substantial proportion of men in our sample reported multiple sex partners and low condom use. As respondents were predominantly HIV-positive MSM with seroconcordant sex partners, risk behaviours, venue attendance and patterns of condom use may not be representative of all MSM with syphilis in Toronto. Nevertheless, collection of behavioural data using an online survey allowed for enhanced descriptive analyses beyond the scope of routine surveillance. In addition to social network analyses, these data are useful to inform targeted prevention and control efforts.

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