There has been a rapid rise in cases of syphilis among men who have sex with men. Rates of infections are now at their highest for the last 60 years and almost all infected are men. Experts are blaming the increased infection rates on gay and bisexual men whose sexual contacts are mostly unprotected. New syphilis diagnoses rose 13% in 2016, with 356 infections – the highest number since 1952. An incredible 83% of new infections were among men who said they have sex with men, while just 20 new cases were among women. The latest increase in syphilis comes after the number diagnoses doubled between 2014 and 2015, from 159 to 316. Of the 295 cases involving gay and bisexual men, 19 said they had had between 10 and 20 sexual partners in the three months prior to diagnosis and six reported more than 20. However, the majority – 195 – said they had had fewer than five, and 27 had had between five and nine. The remainder did not provide an estimate. For heterosexual respondents the number is 4 and less.