Over the past decade, there has been a massive scale-up of primary and secondary prevention services to reduce the population-wide incidence of HIV. However, the impact of these services on HIV incidence has not been demonstrated using a prospectively followed, population-based cohort from South Africa—the country with the world’s highest rate of new infections. To quantify HIV incidence trends in a hyperendemic population, we tested a cohort of 22,239 uninfected participants over 92,877 person-years of observation. We report a 43% decline in the overall incidence rate between 2012 and 2017, from 4.0 to 2.3 seroconversion events per 100 person-years. Men experienced an earlier and larger incidence decline than women (59% vs. 37% reduction), which is consistent with male circumcision scale-up and higher levels of female antiretroviral therapy coverage. Additional efforts are needed to get more men onto consistent, suppressive treatment so that new HIV infections can be reduced among women.

Health policy makers aspire to achieve an HIV treatment 'cascade' in which diagnostic and treatment services are accessed early and routinely by HIV-infected individuals. However, migrants and highly mobile individuals are likely to interact with HIV treatment programs and the healthcare system in ways that reflect their movement through time and place, affecting their successful progression through the HIV treatment cascade. We review recent research that has examined the challenges in effective and sustained HIV treatment for migrants and mobile populations. Mobility is associated with increased risk of antiretroviral therapy (ART) nonadherence, lost to follow-up, deterioration in CD4 count, HIV-related death, development of drug resistance and general noncontinuity of HIV care. Migrants' slow progression through the HIV treatment cascade can be attributed to feelings of confusion, helplessness; an inability to effectively communicate in the native language; poor knowledge about administrative or logistical requirements of the healthcare system; the possibility of deportation or expulsion based on the legal status of the undocumented migrant; fear of disclosure and social isolation from the exile or compatriot group. Travel or transition to the host country commonly makes it difficult for migrants to remain enrolled in ART programs and to maintain adherence to treatment. Existing public health systems fail to properly account for migration, and actionable knowledge of the health requirements of migrants is still lacking. A large body of research has shown that migrants are more likely to enter into the healthcare system late and are less likely to be retained at successive stages of the HIV treatment cascade. HIV-infected migrants are especially vulnerable to a wide range of social, economic and political factors that include a lack of direct access to healthcare services; exposure to difficult or oppressive work environments; the separation from family, friends and a familiar sociocultural environment. Realizing the full treatment and preventive benefits of the UNAIDS 90-90-90 strategy will require reaching all marginalized subpopulations of which migrants are a particularly large and important group.

To quantify the space-time dimensions of human mobility in relationship to the risk of HIV acquisition. We used data from the population cohort located in a high HIV prevalence, rural population in KwaZulu-Natal, South Africa (2000-2014). We geolocated 8006 migration events (representing 1 028 782 km traveled) for 17 743 individuals (≥15 years of age) who were HIV negative at baseline and followed up these individuals for HIV acquisition (70 395 person-years). Based on the complete geolocated residential history of every individual in this cohort, we constructed two detailed time-varying migration indices. We then used interval-censored Cox proportional hazards models to quantify the relationship between the migration indices and the risk of HIV acquisition. In total, 17.4% of participants migrated at least once outside the rural study community during the period of observation (median migration distance = 107.1 km, interquartile range 18.9-387.5). The two migration indices were highly predictive of hazard of HIV acquisition (P < 0.01) in both men and women. Holding other factors equal, the risk of acquiring HIV infection increased by 50% for migration distances of 40 km (men) and 109 km (women). HIV acquisition risk also increased by 50% when participants spent 44% (men) and 90% (women) of their respective time outside the rural study community. This in-depth analysis of a population cohort in a rural sub-Saharan African population has revealed a clear nonlinear relationship between distance migrated and HIV acquisition. Our findings show that even relatively short-distance migration events confer substantial additional risk of acquisition.

HIV/AIDS-related stigma threatens to undermine interventions to prevent and treat HIV/AIDS. To address stigma in a South African community, a thorough understanding of the nature of stigma in the specific cultural context is needed. The goals of this research were to assess the level of stigmatising attitudes among members of a community, compare this to the level of stigma that is perceived to exist within the community and determine to what extent stigmatising attitudes are affected by socio-demographic characteristics, HIV-related experience and cultural beliefs. A questionnaire was completed by 1077 respondents in key areas in two communities in Tshwane, South Africa. The questionnaire included an assessment of HIV-related experience, HIV-knowledge, personal stigma and perceptions of stigma within the community. The findings indicate that the level of personal stigma was significantly lower than that perceived to be present in the community. Respondents who were more stigmatising were older, male, less educated and less knowledgeable about HIV. They were less likely to know someone with HIV and had more traditional cultural viewpoints. While socio-demographic and cultural factors are difficult to change, efforts aimed at increasing people's knowledge and experience of the epidemic occurring in their community could change the level of stigmatising attitudes within their community. Such efforts could have potential benefits in addressing the epidemic and providing greater support for those with HIV.

Unprecedented levels of habitat transformation and rapid urbanisation are changing the way individuals interrelate with the natural environment in developing countries with high economic disparities. Although the potential benefit of green environments for mental health has been recognised, population-level evidence to this effect is scarce. We investigated the effect of green living environment in potentially countering incident depression in a nationally representative survey in South Africa. We used panel data from the South African National Income Dynamics Study (SA-NIDS). Our study used SA-NIDS data from three waves: wave 1 (2008), wave 2 (2010), and wave 3 (2012). Households were sampled on the basis of a stratified two-stage cluster design. In the first stage, 400 primary sampling units were selected for inclusion. In the second stage, two clusters of 12 dwelling units each were drawn from within each primary sampling unit (or 24 dwelling units per unit). Household and individual adult questionnaires were administered to participants. The main outcome, incident depression (ie, incident cohort of 11 156 study participants without significant depression symptoms at their first entry into SA-NIDS), was assessed in the adult survey via a ten item version of the Center for Epidemiologic Studies Depression Scale; a total score of ten or higher was used as a cutoff to indicate significant depressive symptoms. Each participant was assigned a value for green living space via a satellite-derived normalised difference vegetation index (NDVI) based on the GPS coordinates of their household location. Overall, we found uneven benefit of NDVI on incident depression among our study participants. Although the green living environment showed limited benefit across the study population as a whole, our final analysis based on logistic regression models showed that higher NDVI was a predictor of lower incident depression among middle-income compared with low-income participants (adjusted odds ratio [aOR] 0·98, 0·97–0·99, p<0·0001), although when this analysis was broken down by race, its positive effect was particularly evident amongst African individuals. Living in rural areas was linked to lower odds of incident depression (aOR 0·71, 0·55–0·92, p=0·011) compared with study participants residing in urban informal areas that often lack formal planning. Our results imply the importance of green environments for mental wellbeing in sub-Saharan African settings experiencing rapid urbanisation, economic and epidemiological transition, reaffirming the need to incorporate environmental services and benefits for sustainable socioeconomic development. South African Medical Research Council, National Institutes of Health, and Academy of Finland.

It is common to use the mid-point between the latest-negative and earliest-positive test dates as the date of the infection event. However, the accuracy of the mid-point method has yet to be systematically quantified for incidence studies once participants start to miss their scheduled test dates. We used a simulation-based approach to generate an infectious disease epidemic for an incidence cohort with a high (80–100%), moderate (60–79.9%), low (40–59.9%) and poor (30–39.9%) testing rate. Next, we imputed a mid-point and random-point value between the participant’s latest-negative and earliest-positive test dates. We then compared the incidence rate derived from these imputed values with the true incidence rate generated from the simulation model. The mid-point incidence rate estimates erroneously declined towards the end of the observation period once the testing rate dropped below 80%. This decline was in error of approximately 9%, 27% and 41% for a moderate, low and poor testing rate, respectively. The random-point method did not introduce any systematic bias in the incidence rate estimate, even for testing rates as low as 30%. The mid-point assumption of the infection date is unjustified and should not be used to calculate the incidence rate once participants start to miss the scheduled test dates. Under these conditions, we show an artefactual decline in the incidence rate towards the end of the observation period. Alternatively, the single random-point method is straightforward to implement and produces estimates very close to the true incidence rate.