Behavioral HIV-serosurvey reveals clustering of risk factors likely plays a key role in sustaining HIV epidemic in rural KwaZulu-Natal, South Africa

New Human immunodeficiency virus (HIV) infections among adults have decreased in the last ten years in high HIV prevalent countries. However, unsuppressed individuals with high-risk sexual practices can play a key role in transmitting HIV and maintaining the HIV epidemic. We assessed the association between sexual behavior, HIV awareness, antiretroviral therapy (ART) intake and viral suppression, and the age-gender groups most at risk of maintaining HIV transmission in KwaZulu-Natal, South Africa. We conducted a population-based cross-sectional survey including adolescents and adults aged 15 years and above from August to December 2018 in KwaZulu-Natal, South Africa. In this analysis we included only data from HIV-positive participants aged 15–59 years. In total, 862 HIV-positive individuals aged 15–59 years were included, 76.2% (657) were women, and the median age was 36 IQR 29–46 years, 10.1% (95%CI 8.2–12.3) were unaware of their HIV status, 15.8% (95%CI 13.4–18.2) not on ART, and 16.3% (95%CI 13.9–18.9) virally unsuppressed. Among the 671 participants who had sexual intercourse in the preceding year, 46.9% (315) consistently used condoms. Among those who provided information on the number of sexual partners, 7.5% (64/856) reported more than one. Overall, 10.6% (88/831) (95%CI 8.7–12.9) of HIV-positive participants were either at high or very high risk of sexually transmitting HIV. Of these, 42.0% (37/88) (95%CI 32.1–52.7) were women aged 20–34 years, 39.8% (35/88) (95%CI 30.0-50.4) were men aged 20–59 years, 50.0% (44/88) (95%CI 39.6–60.4) were unaware of their HIV-positive status and 76.1% (67/88) (95%CI 66.0–84.0) were not on ART. Within the 2.3% (95%CI 1.5–3.6) individuals at very high risk of HIV transmission (19 individuals virally unsuppressed with more than one partner and inconsistent condom use), 68.4% (13/19) (95%CI 43.4–85.9) were men aged 20 to 59 years, 52.6% (10/19) (95%CI 29.7–74.5) were unaware of their HIV- positive status, and 78.9% (15/19) (95%CI 53.5–92.4) were untreated. Efforts and age-gender targeted interventions to increase HIV diagnosis and HIV-positivity awareness, detect early ART treatment failure, provide enhanced adherence support and second- or third-line ART, as well as promote behavioral-risk reduction interventions, are needed to reduce the pool of individuals at high-risk of transmitting HIV.