The Central Role of Nondisclosed Men Who Have Sex With Men in Human Immunodeficiency Virus-1 Transmission Networks in Guangzhou, China.

Background. Men who have sex with men (MSM) are vulnerable risk group for human immunodeficiency virus (HIV)-1 infection. However, some MSM do not disclose their same-sex behavior and could impact the transmission and prevention of HIV-1 infection. Here, we evaluated the role of nondisclosed MSM in HIV-1 transmission in Guangzhou, China. Methods. The HIV-1 pol sequences were obtained from HIV-infected subjects from 2008 to 2015. A transmission network was constructed using HIV TRAnsmission Cluster Engine (HIV-TRACE) at a pairwise genetic distance of 0.5%. The position of nondisclosed MSM in the network was determined by centrality analysis. Results. Nondisclosed MSM were inferred in 9.92% (61 of 615) of slightly older, self-reported non-MSM (P =.006). They were more likely to be married (P =.002) and less educated (P <.001) than the MSM with whom they clustered. Closeness centrality was bigger for nondisclosed MSM than for MSM (P <.001), indicating the central position of nondisclosed MSM in the networks. The average shortest path length was smaller for nondisclosed MSM than for MSM (P <.001), whereas radiality was bigger for nondisclosed MSM than for MSM, suggesting a relatively greater contribution of nondisclosed MSM in transmitting HIV-1 than MSM. Assortativity analysis indicated that nondisclosed MSM were more likely to link each other with coefficient of 0.025. Conclusions. Nondisclosed MSM are a specific group, and they play an important role in HIV-1 transmission. They could be bisexual and might increase the risk of HIV-1 infection to their sex partners. Therefore, specific prevention and intervention targeting nondisclosed MSM are urgently needed.