Increased Syphilis Testing of Men Who Have Sex With Men: Greater Detection of Asymptomatic Early Syphilis and Relative Reduction in Secondary Syphilis

Background Syphilis rates have increased markedly among men who have sex with men (MSM) internationally. We examined trends in syphilis testing and detection of early syphilis among MSM in Australia. Methods Serial cross-sectional analyses on syphilis testing and diagnoses among MSM attending a national sentinel network of 46 clinics in Australia between 2007 and 2014. Results 359313 clinic visits were included. The proportion of MSM serologically tested for syphilis annually increased in HIV-negative (48% to 91%; Ptrend < .0001) and HIV-positive MSM (42% to 77%; Ptrend < .0001). The mean number of tests per man per year increased from 1.3 to 1.6 in HIV-negative MSM (Ptrend < .0001) and from 1.6 to 2.3 in HIV-positive MSM (Ptrend < .0001). 2799 and 1032 syphilis cases were detected in HIV-negative and HIV-positive MSM, respectively. Among HIV-negative MSM, the proportion of infections that were early latent increased from 27% to 44% (Ptrend < .0001), while the proportion that were secondary decreased from 24% to 19% (Ptrend = .030). Among HIV-positive MSM, early latent infections increased from 23% to 45% (Ptrend < .0001), while secondary infections decreased from 45% to 26% (Ptrend = .0003). Among HIV-positive MSM, decreasing secondary syphilis correlated with increasing testing coverage (r = -0.87; P = .005) or frequency (r = -0.93; P = .001). Conclusions Increases in syphilis screening were associated with increased detection of asymptomatic infectious syphilis and relative falls in secondary syphilis for both HIV-positive and HIV-negative MSM nationally, suggesting interruption of syphilis progression.