Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Sep 23;10(10):ofad481.
doi: 10.1093/ofid/ofad481. eCollection 2023 Oct.

The Syphilis Epidemic Among Heterosexuals Is Accelerating: Evidence From King County, Washington

Anna Berzkalns  1 , Meena S Ramchandani  1   2 , Chase A Cannon  1   2 , Roxanne P Kerani  1   2   3 , Julie C Dombrowski  1   2   3 , Matthew R Golden  1   2   3
Affiliations

The Syphilis Epidemic Among Heterosexuals Is Accelerating: Evidence From King County, Washington

Anna Berzkalns et al. Open Forum Infect Dis. .

Abstract

Background: We characterized the rapid increase in syphilis among cisgender women in King County, Washington, and compared it with trends among cisgender men who have sex with men.

Method: We used surveillance data from King County, 2007 to 2022, to describe incidence trends stratified by syphilis stage, gender, and gender of sex partners; trends in pregnant cases and congenital syphilis; and trends in rapid plasma reagin titer at diagnosis among late/unknown duration cases. We used joinpoint regression to analyze trends.

Results: Among cisgender women, all-stage syphilis incidence remained stable from 2007 to 2010 but then increased by 16.3% per year (95% CI, 12.0%-20.7%) from 2010 to 2020 and 90.1% per year (95% CI, 26.4%-185.9%) from 2020 to 2022. Early syphilis rates rose gradually from 2007 to 2017 (18% per year; 95% CI, 7.4%-29.6%) and then rapidly from 2017 to 2022 (62.5% per year; 95% CI, 24.1%-112.9%). In contrast, the increase in late/unknown duration syphilis incidence was delayed. Among cisgender men who have sex with women, all-stage syphilis remained stable from 2007 to 2014 and increased 25.0% per year (95% CI, 14.0%-37.0%) from 2014 to 2022. Syphilis incidence increased steadily among men who have sex with men, with all-stage incidence increasing 7.0% per year (95% CI, 4.8%-9.2%) from 2007 to 2022. Median rapid plasma reagin titer among late/unknown duration cases increased significantly over the analysis period.

Conclusions: An explosive epidemic of syphilis is ongoing in King County. The delayed increase in asymptomatic late/unknown duration cases relative to early symptomatic cases suggests that there is a large and growing reservoir of recently acquired undiagnosed syphilis in women. New clinical and public health activities are urgently needed to control the growing epidemic.

PubMed Disclaimer

Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts.

Figures

Figure 1.
Figure 1.
Joinpoint regression analysis of trends in the rate of syphilis among cisgender women in King County, Washington, 2007–2022: A, all stages; B, early; C, late/unknown duration.
Figure 2.
Figure 2.
Early syphilis incidence comparing primary and secondary syphilis with early nonprimary nonsecondary syphilis among cisgender women and men who have sex with men (MSM), King County, Washington, 2007–2022.
Figure 3.
Figure 3.
Trends in rapid plasma reagin titer with late/unknown duration syphilis, King County, Washington, 2007–2022: A, cisgender women; B, cisgender men who have sex with women; C, cisgender men who have sex with men.
See this image and copyright information in PMC

References

    1. Centers for Disease Control and Prevention . Sexually transmitted disease surveillance 2021. Atlanta: Centers for Disease Control and Prevention, 2022.
    1. Rolfs RT, Nakashima AK. Epidemiology of primary and secondary syphilis in the United States, 1981 through 1989. JAMA 1990; 264:1432–7. - PubMed
    1. Webster LA, Rolfs RT. Surveillance for primary and secondary syphilis—United States, 1991. MMWR CDC Surveill Summ 1993; 42:13–9. - PubMed
    1. Centers for Disease Control and Prevention . Comparison of early and late latent syphilis–Colorado, 1991. MMWR Morb Mortal Wkly Rep 1993; 42:155–7. - PubMed
    1. Centers for Disease Control and Prevention . Behavioral risk factor surveillance system. Atlanta: Centers for Disease Control and Prevention, 2023. Available at: https://www.cdc.gov/brfss/index.html