Prevalence and Factors Associated With Sexually Transmitted Infections Among People who Inject Drugs in the San Diego-Tijuana Border Region.

Abstract

Background: Few estimates exist of the prevalence of sexually transmitted infections (STIs) and associated risk factors among people who inject drugs (PWID) in the San Diego-Tijuana border region, despite the high prevalence of HIV.

Methods: PWID living in San Diego or Tijuana underwent testing for bacterial STIs between December 2022 and February 2024. Urogenital gonorrhea and chlamydia infections were assessed using a urine test, the Aptima CT/GC assay. Syphilis was assessed using the treponemal Syphilis Health Check Rapid Point-of-Care assay and nontreponemal rapid plasma reagin Treponema pallidum Particle Agglutination test. HIV was tested using the fingerstick tests Miriad HCV/HIV POU+ Test and Oraquick HIV-1. Bacterial STI prevalence was calculated, and logistic regression was conducted to identify correlates of bacterial STI prevalence.

Results: Of 519 participants, 6.0% (95% CI, 3.9%-8.0%) tested positive for 1 or more bacterial STIs. Despite higher HIV prevalence in Tijuana, bacterial STIs were more prevalent in San Diego. Unstable housing, female birth, and US residency were associated with significantly higher adjusted odds of a bacterial STI compared with the reference groups (aOR, 2.61; 95% CI, 1.09-6.27; aOR, 2.41; 95% CI, 1.15-5.08; and OR, 2.79; 95% CI, 1.03-7.53; respectively).

Conclusions: Overall prevalence of bacterial STIs was consistent with other estimates of STIs among PWID in the United States. STI screening guidelines should recommend PWID for routine testing at least annually. Point-of-care testing should be expanded to increase access to STI screening and treatment for marginalized populations.