The final network included 365 men and 33 women; three quarters were Black (n=299). Across all network members, the median age at the initial PCRS interview was 26 years (range, 16 to 56); this decreased significantly over time, from 35.5 in 1995 to 24 in 2010 (p<0.001 for trend). A similar trend was noted for the 29% of the network that was HIV-infected (2 women, 115 men); median age at diagnosis fell from 36.5 in 1993 to 27 in 2010 (p<0.001). Overall, 23% of the network was confirmed to be HIV-uninfected (n=92). Serostatus could not be determined for 47% of the network (n=189), either because PCRS was unable to trace them (n=150) or they refused HIV testing (n=39). Fifty-eight percent of the network self-identified as MSM (217 MSM and 13 MSM who also reported sex with women), but when we included untraceable male partners who had sex with a male client (n=135), the proportion of MSM increased to 92%. Among the 209 clients for whom HIV status was known (), the majority were less than 30 years old (78%); male (96%); Black (97%); and self-identified as MSM (90%). There were no significant differences in any characteristic between HIV-infected and uninfected clients.
Characteristics of Clients with Confirmed HIV Status
depicts the 398 network members and their sexual relationships. The network’s final structure consisted of seven components, the largest of which contained 363 members (91% of the entire network). Sequential figures depicting sexual relationships, incident STIs, and HIV seroconversions over time can be found in Supplementary Digital Content
. Twenty-four individuals acquired HIV after initially appearing as uninfected contacts to known cases of HIV or syphilis, following a median of 1 year in the network (interquartile range [IQR], 0–3 years). Of these seroconverters (arrowheads), 14 were found to have established infection at the time of diagnosis (yellow) and 10 had AHI (red). Overall, 26 clients (22% of known HIV-infected persons) were diagnosed with AHI; all were detected through our statewide pooled nucleic acid screening program.7,8
A Sexual Network of Black Men Who Have Sex with Men, North Carolina, 1989–2010
Indicators of sexual risk activity were frequently observed among HIV-infected clients following their diagnosis. Twenty-five of the 117 network members with HIV (21%) had an incident STI reported to the state following the date of their HIV diagnosis, after a median of 1.91 years (interquartile range, IQR, 1.08–2.85); all were MSM. Syphilis accounted for most of these STIs, with 28 cases diagnosed among 22 individuals; the other 3 men had gonorrhea.
Of the 419 dyads in the network, there were only 27 in which the race of the client and partner differed (6%). We noted wide variation in partnership duration, with a median of 92 days (IQR, 2–365). Over half of all relationships had occurred recently, between 2008–2010 (n=226, 54%), with another 42% distributed between 2003–2007 (n=177).
As shown in blue lines in and boldface in , there were 82 serodiscordant dyads, in which the HIV status of client and sex partner was confirmed to differ; 20% involved clients with AHI. We identified 18 relationships in which clients with AHI named sex partners who were HIV-infected, suggesting possible donor-recipient pairs. Approximately 40% of dyads involved chronically infected clients (n=167), again reflecting ongoing sexual activity among HIV-infected persons following diagnosis. One in five relationships linked HIV-infected clients to partners whose status could not be evaluated (n=96). In 40 dyads, it was not possible to determine clients’ serostatus at the time of sexual activity, since diagnoses of established HIV infection were made after the relationship ended and no prior testing was on record.
Opportunities for Sexual Transmission of HIV across All Dyads
We compared characteristics of dyads featuring traceable versus untraceable partners, and found several significant differences (). Clients with untraceable partners more often reported encounters involving anal intercourse as the only sexual activity (P=0.01), whereas when both oral and anal sex occurred, partners were more often identifiable by PCRS (P=0.03). The number of sexual encounters with a partner influenced traceability, with one-time only partners being more difficult to locate (P<0.001). While the majority of clients reported use of condoms inconsistently or not at all, avoidance of condoms was more often reported by clients with traceable partners (P=0.04). Nearly one in four relationships began by meeting online, with a trend toward such partners being more difficult to trace (P=0.05). Partners met at bars or clubs were readily found by PCRS (P=0.03). In contrast, when clients met their partner at school or work, those individuals were more often untraceable (P=0.002), suggesting that clients may have been reticent to disclose identifying information for classmates or colleagues.
Characteristics of 419 Dyads in Sexual Network
Finally, we evaluated whether client, partner, or dyad-specific characteristics were associated with an outcome of having an untraceable partner (). Bivariate analyses revealed a significant association between having an untraceable partner and having a one-time sexual encounter (risk ratio [RR] 4.44; 95% confidence interval [CI], 2.43, 8.14). Using recreational drugs during sex seemed to independently reduce the risk of having an untraceable partner (RR 0.47; 95% CI, 0.29, 0.77). Being a client with AHI also reduced the risk of a partner being untraceable (RR 0.30; 95% CI, 0.15, 0.56), reflecting PCRS efforts to identify sexual contacts potentially exposed to HIV during the period of heightened infectivity. In a multivariate model, having a one-time sexual encounter (RR 4.51; 95% CI, 2.27, 8.97) and being acutely HIV infected (RR 0.27; 95% CI, 0.08, 0.89) had the strongest influences on the risk of having an untraceable partner.
Client, Sex Partner, and Relationship-Level Predictors of Having an Untraceable Sex Partner