Sexually Transmitted Infections in Melbourne, Australia from 1918 to 2016: nearly a century of data.

Introduction: Our aim was to describe trends in the number of bacterial sexually transmitted infections (STIs) diagnosed at Melbourne's sexual health clinic over a century.

Methods: A retrospective analysis of STI diagnoses (gonorrhoea, infectious syphilis and chancroid) among individuals attending Melbourne's sexual health service over 99 years between 1918 and 2016.

Results: Substantial increases in STI rates coincided with World War II, the 'Sexual Revolution of the 1960s and 1970s', and the last 10 years. Substantial declines coincided with the advent of antibiotics and the HIV/AIDS pandemic. There were also key differences between STIs. Chancroid virtually disappeared after 1950. Syphilis fell to very low levels in women after about 1950 and has only rebounded in men. The declines in gonorrhoea were less marked. A substantial peak in gonorrhoea occurred in women in the early 1970s and rates are currently rising in women, albeit much less than in men.

Conclusions: Both antibiotics and changing sexual behaviour have had a powerful effect on STI rates. These data suggest gonorrhoea is more difficult to control than syphilis or chancroid. Indeed, the past rates suggest substantial endemic gonorrhoea transmission in heterosexuals occurred in the third quarter of last century before the appearance of the HIV pandemic. Worryingly, there is a suggestion that endemic heterosexual gonorrhoea may be returning. The data also suggest that future control of gonorrhoea and syphilis in men who have sex with men is going to be challenging.