{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T06:16:26Z","timestamp":1772172986306,"version":"3.50.1"},"update-to":[{"DOI":"10.1371\/journal.pcbi.1009529","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2021,11,5]],"date-time":"2021-11-05T00:00:00Z","timestamp":1636070400000}}],"reference-count":35,"publisher":"Public Library of Science (PLoS)","issue":"10","license":[{"start":{"date-parts":[[2021,10,26]],"date-time":"2021-10-26T00:00:00Z","timestamp":1635206400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010474","name":"Swiss HIV Cohort Research Foundation","doi-asserted-by":"publisher","award":["#823"],"award-info":[{"award-number":["#823"]}],"id":[{"id":"10.13039\/501100010474","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001711","name":"Schweizerischer Nationalfonds zur F\u00f6rderung der Wissenschaftlichen Forschung","doi-asserted-by":"publisher","award":["#177499"],"award-info":[{"award-number":["#177499"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001711","name":"Schweizerischer Nationalfonds zur F\u00f6rderung der Wissenschaftlichen Forschung","doi-asserted-by":"publisher","award":["#324730_179567"],"award-info":[{"award-number":["#324730_179567"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001711","name":"Schweizerischer Nationalfonds zur F\u00f6rderung der Wissenschaftlichen Forschung","doi-asserted-by":"publisher","award":["BSSGI0_155851"],"award-info":[{"award-number":["BSSGI0_155851"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.ploscompbiol.org"],"crossmark-restriction":false},"short-container-title":["PLoS Comput Biol"],"abstract":"<jats:p>Over the last decade, syphilis diagnoses among men-who-have-sex-with-men (MSM) have strongly increased in Europe. Understanding the drivers of the ongoing epidemic may aid to curb transmissions. In order to identify the drivers of syphilis transmission in MSM in Switzerland between 2006 and 2017 as well as the effect of potential interventions, we set up an epidemiological model stratified by syphilis stage, HIV-diagnosis, and behavioral factors to account for syphilis infectiousness and risk for transmission. In the main model, we used \u2018reported non-steady partners\u2019 (nsP) as the main proxy for sexual risk. We parameterized the model using data from the Swiss HIV Cohort Study, Swiss Voluntary Counselling and Testing center, cross-sectional surveys among the Swiss MSM population, and published syphilis notifications from the Federal Office of Public Health. The main model reproduced the increase in syphilis diagnoses from 168 cases in 2006 to 418 cases in 2017. It estimated that between 2006 and 2017, MSM with HIV diagnosis had 45.9 times the median syphilis incidence of MSM without HIV diagnosis. Defining risk as condomless anal intercourse with nsP decreased model accuracy (sum of squared weighted residuals, 378.8 vs. 148.3). Counterfactual scenarios suggested that increasing screening of MSM without HIV diagnosis and with nsP from once every two years to twice per year may reduce syphilis incidence (at most 12.8% reduction by 2017). Whereas, increasing screening among MSM with HIV diagnosis and with nsP from once per year to twice per year may substantially reduce syphilis incidence over time (at least 63.5% reduction by 2017). The model suggests that reporting nsP regardless of condom use is suitable for risk stratification when modelling syphilis transmission. More frequent screening of MSM with HIV diagnosis, particularly those with nsP may aid to curb syphilis transmission.<\/jats:p>","DOI":"10.1371\/journal.pcbi.1009529","type":"journal-article","created":{"date-parts":[[2021,10,26]],"date-time":"2021-10-26T13:33:44Z","timestamp":1635255224000},"page":"e1009529","update-policy":"https:\/\/doi.org\/10.1371\/journal.pcbi.corrections_policy","source":"Crossref","is-referenced-by-count":8,"title":["Assessing the drivers of syphilis among men who have sex with men in Switzerland reveals a key impact of screening frequency: A modelling study"],"prefix":"10.1371","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9250-4078","authenticated-orcid":true,"given":"Suraj","family":"Balakrishna","sequence":"first","affiliation":[]},{"given":"Luisa","family":"Salazar-Vizcaya","sequence":"additional","affiliation":[]},{"given":"Axel J.","family":"Schmidt","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0310-3764","authenticated-orcid":true,"given":"Viacheslav","family":"Kachalov","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4638-1940","authenticated-orcid":true,"given":"Katharina","family":"Kusejko","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1357-0347","authenticated-orcid":true,"given":"Maria Christine","family":"Thurnheer","sequence":"additional","affiliation":[]},{"given":"Jan A.","family":"Roth","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4133-8177","authenticated-orcid":true,"given":"Dunja","family":"Nicca","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0933-7833","authenticated-orcid":true,"given":"Matthias","family":"Cavassini","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6638-3679","authenticated-orcid":true,"given":"Manuel","family":"Battegay","sequence":"additional","affiliation":[]},{"given":"Patrick","family":"Schmid","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9724-8373","authenticated-orcid":true,"given":"Enos","family":"Bernasconi","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1142-6723","authenticated-orcid":true,"given":"Huldrych F.","family":"G\u00fcnthard","sequence":"additional","affiliation":[]},{"given":"Andri","family":"Rauch","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9220-8348","authenticated-orcid":true,"given":"Roger D.","family":"Kouyos","sequence":"additional","affiliation":[]},{"name":"the Swiss HIV Cohort Study (SHCS)","sequence":"additional","affiliation":[]}],"member":"340","published-online":{"date-parts":[[2021,10,26]]},"reference":[{"issue":"22","key":"pcbi.1009529.ref001","article-title":"Sexually transmitted infections and chlamydia screening in England, 2016","volume":"10","author":"Public Health England","year":"2016","journal-title":"Health Protection Report."},{"key":"pcbi.1009529.ref002","first-page":"147","article-title":"The resurgence of syphilis in high-income countries in the 2000s: a focus on Europe","author":"G Spiteri","year":"2019","journal-title":"Epidemiol Infect"},{"key":"pcbi.1009529.ref003","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jaad.2019.02.073","article-title":"Sexually acquired syphilis: Historical aspects, microbiology, epidemiology, and clinical manifestations","volume":"82","author":"AK Forrestel","year":"2020","journal-title":"J Am Acad Dermatol"},{"key":"pcbi.1009529.ref004","unstructured":"BAG-Bulletin 47. Federal Office of Public Health, Switzerland; 2018."},{"key":"pcbi.1009529.ref005","doi-asserted-by":"crossref","first-page":"1907","DOI":"10.1097\/QAD.0b013e32833bfe21","article-title":"Occurrence, risk factors, diagnosis and treatment of syphilis in the prospective observational Swiss HIV Cohort Study","volume":"24","author":"MC Thurnheer","year":"2010","journal-title":"AIDS Lond Engl"},{"key":"pcbi.1009529.ref006","doi-asserted-by":"crossref","first-page":"e5849","DOI":"10.1097\/MD.0000000000005849","article-title":"Factors associated with syphilis incidence in the HIV-infected in the era of highly active antiretrovirals","volume":"96","author":"M Shilaih","year":"2017","journal-title":"Medicine (Baltimore)."},{"key":"pcbi.1009529.ref007","article-title":"Repeated Syphilis Episodes in HIV-Infected Men Who Have Sex With Men: A Multicenter Prospective Cohort Study on Risk Factors and the Potential Role of Syphilis Immunity","volume":"7","author":"JA Roth","year":"2020","journal-title":"Open Forum Infect Dis"},{"key":"pcbi.1009529.ref008","article-title":"Effect of syphilis infection on HIV acquisition: a systematic review and meta-analysis","author":"MY Wu","year":"2020","journal-title":"Sex Transm Infect"},{"key":"pcbi.1009529.ref009","doi-asserted-by":"crossref","first-page":"1550","DOI":"10.1016\/S0140-6736(16)32411-4","article-title":"Syphilis","volume":"389","author":"EW Hook","year":"2017","journal-title":"The Lancet"},{"key":"pcbi.1009529.ref010","doi-asserted-by":"crossref","first-page":"1157","DOI":"10.1080\/09540121.2019.1612006","article-title":"Risk factors of syphilis co-infection among HIV-infected men who have sex with men in Tel-Aviv, Israel","volume":"31","author":"A Polansky","year":"2019","journal-title":"AIDS Care"},{"key":"pcbi.1009529.ref011","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1071\/SH14174","article-title":"Syphilis transmission: a review of the current evidence","volume":"12","author":"JE Stoltey","year":"2015","journal-title":"Sex Health"},{"key":"pcbi.1009529.ref012","first-page":"2","article-title":"Increases in Condomless Sex in the Swiss HIV Cohort Study","author":"RD Kouyos","year":"2015","journal-title":"Open Forum Infect Dis"},{"key":"pcbi.1009529.ref013","first-page":"1","article-title":"Sexually Transmitted Diseases Treatment Guidelines, 2015","volume":"64","author":"KA Workowski","year":"2015","journal-title":"MMWR Recomm Rep Morb Mortal Wkly Rep Recomm Rep"},{"key":"pcbi.1009529.ref014","doi-asserted-by":"crossref","first-page":"966","DOI":"10.2307\/4591989","article-title":"Epidemiologic treatment of contacts to infectious syphilis","volume":"78","author":"MB Moore","year":"1963","journal-title":"Public Health Rep"},{"key":"pcbi.1009529.ref015","doi-asserted-by":"crossref","first-page":"711","DOI":"10.1001\/jama.1971.03190180033006","article-title":"Therapy for incubating syphilis. Effectiveness of gonorrhea treatment","volume":"218","author":"AL Schroeter","year":"1971","journal-title":"JAMA"},{"key":"pcbi.1009529.ref016","article-title":"Routinized Syphilis Screening Among Men Living With Human Immunodeficiency Virus: A Stepped Wedge Cluster Randomized Controlled Trial","author":"AN Burchell","year":"2021","journal-title":"Clin Infect Dis"},{"key":"pcbi.1009529.ref017","doi-asserted-by":"crossref","first-page":"298","DOI":"10.1097\/OLQ.0b013e3181ca3c0a","article-title":"Frequent testing of highly sexually active gay men is required to control syphilis","volume":"37","author":"RT Gray","year":"2010","journal-title":"Sex Transm Dis"},{"key":"pcbi.1009529.ref018","article-title":"Screen more or screen more often? Using mathematical models to inform syphilis control strategies","author":"AR Tuite","year":"2013","journal-title":"BMC Public Health"},{"key":"pcbi.1009529.ref019","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.mbs.2016.03.017","article-title":"A mathematical model of syphilis transmission in an MSM population","volume":"277","author":"CM Saad-Roy","year":"2016","journal-title":"Math Biosci"},{"key":"pcbi.1009529.ref020","doi-asserted-by":"crossref","first-page":"3573","DOI":"10.1016\/j.apm.2015.09.090","article-title":"Population dynamics of a mathematical model for syphilis","volume":"40","author":"E Iboi","year":"2016","journal-title":"Appl Math Model"},{"key":"pcbi.1009529.ref021","unstructured":"Population data, 1950\u20132018. Federal statistical office, Switzerland; 2019. Available: https:\/\/www.bfs.admin.ch\/bfs\/en\/home\/statistics\/population.assetdetail.9466635.html"},{"key":"pcbi.1009529.ref022","article-title":"The Denominator problem: estimating the size of local populations of men-who-have-sex-with-men and rates of HIV and other STIs in Switzerland","author":"AJ Schmidt","year":"2019","journal-title":"Sex Transm Infect"},{"key":"pcbi.1009529.ref023","doi-asserted-by":"crossref","first-page":"2509","DOI":"10.1097\/QAD.0000000000000878","article-title":"The HIV care cascade in Switzerland: reaching the UNAIDS\/WHO targets for patients diagnosed with HIV","volume":"29","author":"P Kohler","year":"2015","journal-title":"AIDS Lond Engl"},{"key":"pcbi.1009529.ref024","doi-asserted-by":"crossref","first-page":"1179","DOI":"10.1093\/ije\/dyp321","article-title":"Cohort profile: the Swiss HIV Cohort study.","volume":"39","author":"Swiss HIV Cohort Study","year":"2010","journal-title":"Int J Epidemiol"},{"key":"pcbi.1009529.ref025","unstructured":"Lociciro S, Bize R. Les comportements face au VIH\/Sida des hommes qui ont des rapports sexuels avec des hommes. Enqu\u00eate Gaysurvey 2014. Lausanne, Institut universitaire de m\u00e9decine sociale et pr\u00e9ventive, 2015 (Raisons de sant\u00e9 253)."},{"key":"pcbi.1009529.ref026","volume-title":"R: A language and environment for statistical computing","author":"R Core Team","year":"2020"},{"key":"pcbi.1009529.ref027","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v033.i03","article-title":"Inverse Modelling, Sensitivity and Monte Carlo Analysis in R Using Package FME","volume":"33","author":"K Soetaert","year":"2010","journal-title":"J Stat Softw"},{"key":"pcbi.1009529.ref028","unstructured":"EMIS-2017 \u2013The European Men-Who-Have-Sex-With-Men Internet Survey. In: European Centre for Disease Prevention and Control [Internet]. 29 Aug 2019 [cited 15 Jun 2020]. Available: https:\/\/www.ecdc.europa.eu\/en\/publications-data\/emis-2017-european-men-who-have-sex-men-internet-survey"},{"key":"pcbi.1009529.ref029","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1007\/s12105-009-0127-0","article-title":"Syphilis: The Renaissance of an Old Disease with Oral Implications","volume":"3","author":"G Ficarra","year":"2009","journal-title":"Head Neck Pathol"},{"key":"pcbi.1009529.ref030","doi-asserted-by":"crossref","first-page":"567","DOI":"10.1136\/sextrans-2013-051494","article-title":"Sex on demand: geosocial networking phone apps and risk of sexually transmitted infections among a cross-sectional sample of men who have sex with men in Los Angeles County","volume":"90","author":"MR Beymer","year":"2014","journal-title":"Sex Transm Infect"},{"key":"pcbi.1009529.ref031","doi-asserted-by":"crossref","first-page":"360","DOI":"10.1097\/OLQ.0000000000000454","article-title":"Online Sex Partner Meeting Venues as a Risk Factor for Testing HIV Positive Among a Community-Based Sample of Black Men Who Have Sex With Men.","volume":"43","author":"LA Eaton","year":"2016","journal-title":"Sex Transm Dis"},{"key":"pcbi.1009529.ref032","doi-asserted-by":"crossref","first-page":"462","DOI":"10.1097\/OLQ.0000000000000784","article-title":"A Network Analysis of Sexually Transmitted Diseases and Online Hookup Sites Among Men Who Have Sex With Men","volume":"45","author":"PA Chan","year":"2018","journal-title":"Sex Transm Dis"},{"key":"pcbi.1009529.ref033","article-title":"Grindr Users Take more Risks, but are more Open to HIV Pre-Exposure Prophylaxis: Could this Dating App Provide Platform for HIV Prevention Outreach?","author":"M Hoenigl","year":"2019","journal-title":"Clin Infect Dis Off Publ Infect Dis Soc Am"},{"key":"pcbi.1009529.ref034","unstructured":"Hicks BC, Clement M. Syphilis: Epidemiology, pathophysiology, and clinical manifestations in HIV-uninfected patients. Available: https:\/\/www.uptodate.com\/contents\/syphilis-epidemiology-pathophysiology-and-clinical-manifestations-in-hiv-uninfected-patients"},{"key":"pcbi.1009529.ref035","doi-asserted-by":"crossref","first-page":"617","DOI":"10.1111\/hiv.12878","article-title":"2019 update of the European AIDS Clinical Society Guidelines for treatment of people living with HIV version 10.0","volume":"21","author":"L Ryom","year":"2020","journal-title":"HIV Med."}],"updated-by":[{"DOI":"10.1371\/journal.pcbi.1009529","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2021,11,5]],"date-time":"2021-11-05T00:00:00Z","timestamp":1636070400000}}],"container-title":["PLOS Computational Biology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pcbi.1009529","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,11,5]],"date-time":"2021-11-05T13:35:15Z","timestamp":1636119315000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pcbi.1009529"}},"subtitle":[],"editor":[{"given":"Benjamin Muir","family":"Althouse","sequence":"first","affiliation":[]}],"short-title":[],"issued":{"date-parts":[[2021,10,26]]},"references-count":35,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2021,10,26]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pcbi.1009529","relation":{"has-preprint":[{"id-type":"doi","id":"10.1101\/2021.01.20.21250179","asserted-by":"object"}]},"ISSN":["1553-7358"],"issn-type":[{"value":"1553-7358","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,26]]}}}