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Syphilis epidemic

A monthly review of real-time syphilis data.


Short URL: kingcounty.gov/syphilis

In 2021, there were 11 cases of congenital syphilis (parent to child transmission) in King County, a more than 10-fold increase compared to 2020 when only 1 case of congenital syphilis was identified. Congenital syphilis is a devastating disease that can lead to miscarriage, stillbirth, neonatal death, prematurity, and long-term health outcomes in infants affected. Congenital syphilis is a consequence of rising rates of syphilis among heterosexual cis-men and -women. Syphilis cases among gay, bisexual, and other men who have sex with men are also very high and rising. Currently, reported syphilis cases are low (less than 1%) among transgender and non-binary people.

In response, Public Health — Seattle & King County has created a Syphilis task force which includes a monthly review of real time syphilis data to guide public health interventions. The data presented on this page report on the monthly syphilis case counts by population in Seattle and King County. These data are not final and are subject change. Only the annual STD Epidemiology Report should be used for the most accurate reporting.

Syphilis: An Accelerating Epidemic

Incidence of all-stage syphilis among cisgender women, King County, Washington 2007-2022

Incidence of all-stage syphilis among cisgender women, King County, Washington 2007-2022

Syphilis cases by stage, King County, WA
August 2024 (824 KB) January 2024 (878 KB)
July 2024 (824 KB) December 2023 (822 KB)
June 2024 (805 KB) November 2023 (824 KB)
May 2024 (818 KB) October 2023 (821 KB)
April 2024 (821 KB) September 2023 (825 KB)
March 2024 (819 KB) August 2023 (816 KB)
February 2024 (821 KB)  

2024 Syphilis testing guidelines for cisgender women (including pregnant individuals) and cisgender men who have sex with women*

  • Sexually active individuals aged 45 and under who have not been tested since January 2021 should get tested for syphilis.
  • Sexually active individuals should test annually and whenever they get medical care (up to every 3 months) if they: (1) use injection drugs (2) use methamphetamine or nonprescription opioids (3) are houseless or unstably housed (4) have transactional sex (5) entered a correctional facility or have been  incarcerated in the last 2 years (6) had syphilis or gonorrhea in the last 2 years (7) are living with HIV and are sexually active outside of a mutually monogamous relationship (8) are a woman whose male partners have sex with both men and women (9) have a sex partner with any of the above risk factors for syphilis.
  • Pregnant individuals should be tested during their: (1) first prenatal care visit (2) 3rd-trimester [laboratory testing done during the 24th-28th week of pregnancy] (3) time of delivery.
  • Pregnant individuals who have not had prenatal care, or their prenatal care status is unknown, should be tested any time they are in a clinical setting (i.e., emergency department, jail, substance use treatment facilities, OB triage, labor and delivery, etc.)
  • Pregnant individuals should also be tested if their fetus has died after 20 weeks.

*Syphilis testing guidelines for other populations can be found in the 2024 Syphilis Screening Guidelines (431 KB)

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