(P141) LOW CASE-FINDING FROM SYPHILIS PARTNER SERVICES IN KING COUNTY, WA

Background:
While partner services (PS) are traditionally a core component of public health efforts to control syphilis, its effectiveness in addressing the current epidemic is uncertain.  We evaluated case-finding efficacy of PS and how PS may have helped index cases receive syphilis treatment.

Methods:
We analyzed routinely collected syphilis PS data for King County, WA from 2023 and compared to outcomes observed in 2017. Analyses evaluated the following indices measured per interviewed index case: contact (partners named), epidemiologic (partners treated) and brought-to-treatment (infected partners treated).  We assessed how many index cases were treated after their PS interview.  Analyses were stratified into the following groups: cisgender (cis-) men and transgender or non-binary persons who have sex with men (MSM/trans/NB); cis-men who have sex with women (MSW); and cis-women.

Results:
In 2023, 1,662 cases of syphilis were reported, of which 1,094 (66%) were initiated for PS and 464 (28%) were interviewed. DIS initiated 31% (225/716) of cases in MSM/trans/NB persons, of whom 42% (95) were interviewed.  Among MSW/cis-women, DIS initiated 94% (741/787) of cases, of which 45% (355) were interviewed. In 2017, the contact, epidemiologic, and brought to treatment indices, respectively, were as follows: MSM/trans/NB (1.04, 0.53, 0.10), MSW (0.68, 0.32, 0.09), cis-women (1.31, 0.42, 0.19).  In 2023, compared to 2017, all three indices among all three populations declined: MSM/trans/NB (0.24, 0.04, 0.02), MSW (0.46, 0.09, 0.06), cis-women (0.59, 0.13, 0.06).  Only 21 partners, 13 diagnosed with syphilis, and 72 (16%) index cases were treated after DIS interviews.

Conclusion:
Syphilis PS indices have declined substantially in King County. Syphilis PS seldom lead to partner treatment, with the lowest success occurring in MSM/trans/NB index cases. PS facilitate index case treatment in some cases. Among other jurisdictions with similar outcomes, health departments should investigate modifying their approach to PS and investing in alternative syphilis case-finding activities.