TARGETED HIV AND STI SCREENING STRATEGIES AMONGST MSM IN BALTIMORE, AND THE IMPACT ON THE HIV EPIDEMIC: Using Agent Based Models to Study STI- HIV Co-infection Dynamics

Co-infection of men who have sex with men who have sex with men (MSM) with HIV and and Neisseria gonorrhoeae/Chlamydia trachomatis (NG/CT) remains a significant public health problem in the United States due to co-infection dynamics creating an epidemiologic phenomenon whereby co-epidemics of HIV and NG/CT (along with other STIs) help propagate each other. One of the key components of the US National AIDS Strategy revolves around the HIV Care Continuum, in which HIV-infected persons are diagnosed, linked to care, retained in care and virally suppressed to prevent transmission. Screening for HIV is the entry point for the care continuum and various understanding the most efficacious strategies for this is of utmost importance to help identify HIV-infected persons and link them to care. We used an agent-based model to test three screening strategies for efficacy: targeting high-risk MSM, increased general HIV screening, and improved NG/CT screening amongst HIV-infected MSM. Targeting high-risk MSM and increased general HIV screening produced significant decreases in the HIV and NG/CT incidence relative to baseline, but the former produced steeper declines while simultaneously testing thousands less persons. Improved NG/CT screening amongst HIV-infected MSM has no impact on the incidence rate of either. The targeting high-risk MSM strategy produced steep declines in HIV incidence, and efficiently achieved this in less HIV tests given per year compared to the general HIV screening. This suggests that targeting high-risk MSM may be a more effective approach to achieve a reduction in HIV incidence. Furthermore, it suggests that the HIV epidemic amongst MSM in Baltimore may be concentrated amongst a subset of the MSM population