Résumé
Background. HIV-serodiscordant couples are at high risk of HIV transmission. In sub-Saharan Africa, HIV-serodiscordant couples contribute average 30% of all new infections in the region. Objectives. To quantify the prevalence of HIV-serodiscordant couples and evaluate steps of the HIV cascade of care among people living with HIV in serodiscordant relationships in four high-prevalence settings in sub-Saharan Africa. Methods. Four HIV prevalence surveys were conducted: in Ndhiwa (Kenya) in 2012, in Chiradzulu (Malawi) in 2013, and in Gutu (Zimbabwe) and Nsanje (Malawi) in 2016. Eligible individuals aged 15 - 59 years were asked to participate in voluntary rapid HIV testing. Viral load and CD4 counts were measured on those who tested HIV-positive. A couple was defined as a man and a woman who reported being married or cohabiting and were living together in the same household. Results. Among 4 385 couples, the prevalence of HIV serodiscordancy was 10.9% (95% confidence interval (CI) 10.2 - 11.5) overall, ranging from 6.7% (95% CI 5.6 - 7.9) in Nsanje to 15.8% (95% CI 14.5 - 17.3) in Ndhiwa. Men were the HIV-positive partner in 62.7% of the serodiscordant couples in Ndhiwa, in 60.4% in Gutu, in 48.8% in Chiradzulu and in 50.9% in Nsanje. Status awareness among HIV-positive partners in serodiscordant couples ranged from 45.4% in Ndhiwa to 70.7% in Gutu. Viral load suppression (VLS) ranged from 33.9% in Ndhiwa to 68.5% in Nsanje. VLS was similar by sex in three settings, Ndhiwa (37.8% (men) v. 27.8% (women); p=0.16), Nsanje (60.7% v. 76.9%; p=0.21) and Gutu (48.2% v. 55.6%; p=0.63), and dissimilar by sex in Chiradzulu (44.4% v. 62.7%; p=0.03). Conclusions. Low HIV status awareness and poor VLS among HIV-positive partners are major gaps in preventing transmission among serodiscordant couples. Intensifying programmes that target couples to test for HIV and timely antiretroviral therapy initiation could increase VLS and reduce HIV transmission.