Despite persistent HIV and syphilis epidemics among men who have sex with men (MSM), the relationship between HIV and syphilis contact networks has not been well characterized. We aimed to measure interconnectivity between HIV and syphilis contact networks among MSM and identify network communities with heightened interconnectivity of the syphilis network with the HIV network.
Using contact-tracing data, we generated independent and combined HIV and syphilis networks for all MSM diagnosed with HIV or early syphilis, respectively, in North Carolina between 2015 and 2017. We treated the independent networks as layers and identified network communities, or groups of densely connected nodes, in the 2-layer network. We assessed interconnectivity by comparing the mean node degree among syphilis network members in the syphilis network alone versus the combined HIV/syphilis network, both overall and by network community.
The syphilis network was interconnected with the HIV network, especially in network communities with younger median age, higher proportions of persons self-identifying as Black, non-Hispanic, and higher proportions of syphilis cases diagnosed at sexually transmitted disease clinics.
Interconnected contact networks underlie HIV and syphilis epidemics among MSM, particularly among young, Black MSM. Intensified transmission prevention interventions within highly interconnected network communities may be particularly beneficial.