High transmission risk in HIV-1 molecular transmission network among MSM is related to unsafe sexual behavior and adverse childhood experiences: a case-control study.

Background: Molecular transmission networks enable successful identification of core transmitters compared to traditional epidemiological surveillance; however, behavioral characteristics and psychological drivers of these spreaders remain poorly characterized. Adverse childhood experiences (ACEs) are significantly more common among HIV-positive individuals than in the general population; yet empirical evidence showing that ACEs increase transmission risk among men who have sex with men (MSM) remains limited. This study investigates transmission risk in molecular network associations with sexual behaviors and adverse childhood experiences among MSM. Methods: This study was a Case-Control Study based on molecular networks. A molecular transmission network was constructed using HIV-1 pol sequences from 1,691 newly diagnosed MSM in Guangzhou (2018-2020). Cases were defined as individuals with a network degree ≥3 (high transmission risk group) and controls were defined as those with a degree <3 (low transmission risk group), matched 1:1 by age (±5 years). Data on sexual behavior and adverse childhood experiences were collected via electronic questionnaires from 2023 to 2024. Logistic regression was used to analyze associations between these factors and transmission risk. Results: Among 1,691 participants, 40.57% were included in the molecular network, comprising 238 high-risk and 448 low-risk individuals. After matching, 119 pairs were analyzed. High-risk MSM exhibited significantly elevated transmission risks associated with sexually transmitted infections (aOR = 2.947, 95% CI: 1.084-8.008); versatile sexual role (aOR = 2.856, 95% CI: 1.323-6.165); infrequent sexual activity (monthly: aOR = 6.487, 95% CI: 1.594-26.407; ≤quarterly: aOR = 6.708, 95% CI: 1.668-26.984); no stable partner or multiple stable partners (aOR = 2.516, 95% CI: 1.231-5.140); childhood sexual abuse (aOR = 2.791, 95% CI: 1.268-6.146); physical neglect (aOR = 2.386, 95% CI: 1.087-5.238). Conclusion: Unsafe sexual behavior and ACEs significantly increased the likelihood of becoming a core transmitter within MSM networks. Integrating screening for these factors into prevention programs could optimize early identification of high-transmission-risk MSM and enhance precision interventions.