(P37) POPULATION-BASED SAMPLING FOR SYPHILIS SURVEILLANCE, CHICAGO, IL

Background:
Between 2018 and 2022, the Chicago Department of Public Health (CDPH) saw a 97% increase in all stage syphilis within sex at birth females (SABF). CDPH reallocated public health intervention (PHI) staff to follow up on SABF cases to respond. As such, PHI was unable to conduct comprehensive interventions among sex at birth males (SABM). To better understand current trends among SABMs, CDPH conducted enhanced syphilis surveillance to identify factors to inform interventions among this group.

Methods:
A 20% random sample was selected for investigation among lab-confirmed syphilis positive SABMs reported through the Chicago Health Information Management System. Individuals were batch sampled weekly using a simple random sample methodology after deduplication within SAS. Case data was collected through telephone interviews and stored in REDCap.

Results:
Between September 2023 - January 2024, complete contact attempts were made on 240 sampled individuals with 60.8% successfully contacted and 28.9% (N= 69) interviewed. Among interviewed participants: median age was 31 years, 31.9% Non-Hispanic Black, 26.1% Non-Hispanic White, 26.1% Hispanic, 10.1% Non-Hispanic Multiracial, and 5.7% Other Race Indicated. During their syphilis testing event, 87.0% (60/69) were tested for HIV. 20.3% (14/69) of sample self-reported living with HIV, with 100% taking antiretroviral medications. PrEP usage was high at 54.5% (30/55) of respondents. Approximately 87% indicated having same sex partners with a median of 2 partners in the last three months. For finding partners, participants most often used online dating apps (53.6%), bars and clubs (29.0%), social media (21.7%), social networks (15.9%), and bathhouses (8.7%).

Conclusion:
This data indicates a need for targeted public health interventions coupled with access to social media platforms and dating applications for disease intervention activities. Methodology proved viable for collecting health information useful in informing prevention activities, however new strategies are needed to incentivize participation. Additional assessments are needed to ensure representativeness of the sample.