The Syphilis Epidemic Among Heterosexuals is Accelerating: Evidence from King County, Washington

Abstract Background We characterized the rapid increase in syphilis among cisgender women King County, WA and compared it to trends men who have sex with (MSM). Methods used surveillance data from WA, 2007-2022 described incidence stratified by stage, gender of partners; pregnant cases congenital syphilis; RPR titer at diagnosis late/unknown duration cases. joinpoint regression analyze trends. Results Among women, all-stage remained stable 2007-2010, increased 16.3% (95% CI, 12.0-20.7%) per year 2010-2020 90.1% 26.4-185.9%) 2020-2022. Early rates rose gradually 2007-2017 (18% [95% 7.4-29.6%] year), then rapidly 2017-2022 (62.5% 24.1-112.9%] year). In contrast, was delayed. 2007-2014 25.0% 14.0-37.0%) 2014-2022. Syphilis steadily MSM, increasing 7.0% 4.8-9.2%) 2007-2022. Median significantly over analysis period. Conclusions An explosive epidemic is ongoing WA. Delayed asymptomatic relative early symptomatic suggests that there a large growing reservoir recently acquired, undiagnosed women. New clinical public health activities are urgently needed control epidemic.