Official websites use. Share sensitive information only on official, secure websites. All other authors declare no competing interests. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 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 and 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. The main model reproduced the increase in syphilis diagnoses from cases in to cases in Defining risk as condomless anal intercourse with nsP decreased model accuracy sum of squared weighted residuals, 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 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 The model suggests that reporting nsP regardless of condom use is suitable for risk stratification when modelling syphilis transmission.
Syphilis, one of the most common sexually transmitted infections, remains a major public health problem. Over the last decade, a rising number of diagnoses especially in men-who-have-sex-with-men MSM was observed in Western Europe and Northern America.
In Switzerland, the number of syphilis diagnoses in MSM tripled between and In this study, we used a mathematical model to assess the drivers of this increase among MSM in Switzerland. Our model could reproduce the increase in syphilis diagnoses in both MSM with and without HIV diagnosis between and Furthermore, we found that reported sex with non-steady partners is a useful proxy of behavioral risk.
Considering counterfactual scenarios, we showed that increasing the screening frequency for syphilis among MSM with HIV diagnosis and with non-steady partners from once a year to twice per year can reduce syphilis incidence by Syphilis, a sexually transmitted infection caused by bacteria Treponema pallidum , remains a major public health problem.
