Investigating a sexual network of black men who have sex with men: implications for transmission and prevention of HIV infection in the United States

Abstract

Background: HIV infections increased 48% among young Black men who have sex with men (MSM) in the United States between 2006 and 2009. Incomplete understanding of this trend undermines prevention strategy development. We investigated a sexual network to characterize the risk environment in which young Black MSM acquire HIV.

Methods: Persons reported to the state after diagnosis of HIV or syphilis were included, along with sexual partners. We used network mapping alongside descriptive and bivariate statistics to characterize network connections. Generalized linear models assessed predictors of having untraceable sex partners.

Results: The network included 398 individuals and 419 sexual relationships. Three-quarters were Black (n = 299); 92% were MSM. Median age at first network appearance was 26 years and decreased over time (P < 0.001). HIV prevalence was at least 29% (n = 117); serostatus was unknown for 47% of the network, either because they were untraceable (n = 150) or refused HIV testing (n = 39). One in 5 network members diagnosed with HIV had a subsequent incident sexually transmitted infection. In multivariable models, one-time encounters increased the risk of having an untraceable partner (risk ratio = 4.51, 95% CI: 2.27 to 8.97), whereas being acutely HIV infected at diagnosis reduced it (risk ratio = 0.27, 95% CI: 0.08 to 0.89).

Conclusions: HIV prevalence in this sexual network of young Black MSM rivals that of sub-Saharan Africa, reflecting dramatically increased risk of acquiring HIV from the moment one entered the network. Prevention efforts for this population must consider the effect of sexual networks on HIV risk and find ways of leveraging network structure to reduce transmission.

Figure 1

A Sexual Network of Black Men Who Have Sex with Men, North Carolina, 1989–2010 The final network consisted of 365 men (circles) and 33 women (inverted triangles). The seven separate components of the network are shown; the largest contains 363 nodes, or 91% of all network members. Of the 117 HIV-infected clients, 24 became HIV-infected after initially appearing in the network as uninfected contacts to known cases of HIV or syphilis (arrowheads); 10 were diagnosed with acute HIV (red symbols) and 14 with established, chronic HIV (yellow symbols). Thick blue lines indicate the 82 confirmed relationships in which one partner was HIV-infected and the other uninfected at the time of sex.