Background
Representative data on HIV transmission networks and incident infections are rare but essential for targeting HIV prevention services. We conducted a contact tracing investigation of individuals with incident HIV.
Methods
From 2021-24, a matched case-control study was nested within the Rakai Community Cohort Study, a population-based longitudinal HIV surveillance cohort spanning 34 Ugandan communities. Persons with incident HIV were matched to HIV-negative controls based on age, sex, religion, and community. Sexual partner contact details (name, residence) were elicited; for female sex worker (FSW) partners without complete contact details, venue information was collected. Named and potential FSWs partners at venues were enrolled and tested for HIV and viremia (>1,000 copies/ml). Conditional logistic regression compared sexual networks and risk profiles.
Results
We identified 99 women and 87 men with incident HIV and matched them to 186 controls. Male cases elicited 321 partners compared to 188 from male controls. Female cases elicited 183 partners versus 118 from female controls. Male cases lacked complete contact details for most partners (177, 55.1%) in contrast to male controls (60, 31.9%), female cases (60, 32.8%), or female controls (22, 18.6%); most of these 177 partners (62.1%) were venue-based FSWs. We enrolled 437 named partners from cases (n=237) and controls (n=200), respectively (Figure). From 27 venues (4-200 FSW/venue) linked to 35 male cases, we enrolled 227 FSWs, of whom 36% (n=80) were living with HIV. Most venues (73%) were unknown to local outreach services. Compared to controls, cases had significantly higher odds of having >=1 partner with HIV (conditional odds ratio [cOR]=9.63; 95%CI:4.65–19.93) and >=1 partner with viremia (cOR=8.00; 95%CI:2.83–22.62). Male cases had 16.5 times higher odds than controls of reporting ≥1 FSW partner (95%CI:3.96–68.76). PrEP use was rare among HIV-negative partners of persons with viremia (2.9%; 2/70) and FSWs (6.9%, 10/144).
Conclusions
Incident HIV among men was strongly linked to reporting FSW sexual partners. Many men had no partner contact details beyond venue information. Incorporating venue-based partner elicitation into partner notification services could improve HIV case notification and service outreach. Additionally, low PrEP use among HIV-negative partners of viremic individuals including FSWs highlights a significant unmet need for services and an urgency for targeted intervention.