Using geospatial mapping to design HIV elimination strategies for sub-Saharan Africa

Abstract

UNAIDS, and the WHO, plan to use “treatment as prevention” (TasP) to eliminate HIV. The rationale is that treating HIV-infected individuals reduces their infectivity. We present a novel geostatistical framework for implementing the rollout of TasP in sub-Saharan Africa. We focus on Lesotho, because UNAIDS has identified their epidemic as a priority for elimination. Our framework is based on a density of infection (DoI) map that we generate by gridding high-resolution demographic data, and spatially smoothing georeferenced HIV-testing data. The map reveals the geographic dispersion pattern of HIV-infected individuals, both diagnosed and undiagnosed. We use the map to design a treatment allocation strategy that optimizes, under resource constraints, the efficiency of resource utilization. Using this strategy (rather than the current treatment allocation strategy) would make it easier to find, diagnose and treat individuals. We also use our framework to evaluate the feasibility of UNAIDS’ elimination plan. We show the feasibility of reaching specific treatment coverage levels depends upon the geographic dispersion pattern of HIV-infected individuals, and that this pattern reflects the spatial demographics of Lesotho. Only 20% of HIV-infected individuals live in urban areas; most live in rural settlements where the DoI is less than six infected individuals/km2. Given these conditions, it will be almost impossible to reach a very high coverage of treatment. Therefore, the UNAIDS elimination plan is unlikely to succeed in Lesotho. Taken together, our results show that the spatial demographics of populations will significantly hinder, and may even prevent, the elimination of HIV in sub-Saharan Africa.

Geospatial mapping to identify feasible HIV prevention and treatment strategies that target specific settings

“…The DOI map is a reflection of the spatial diffusion of the epidemic in the general population of Lesotho, the size and dispersion patterns of rural and urban settlements, and geographic variation in population density (1). In the study, the geographic dispersion pattern of HIV-positive (both diagnosed and undiagnosed) individuals mirrors the spatial demographics of the population, and reflect high levels of variability within, as well as between, different healthcare districts.…”

“…The paper recently published by Coburn, Okano, and Blower (1) proposes the use of geospatial mapping to optimize resource allocation to eliminate HIV in Lesotho, a small landlocked country in Southern Africa with a population of about 2 million and an HIV prevalence of approximately 25% in urban centers and 21% in rural settlements. In their study, the authors describe a geostatistical framework for designing a novel treatment as prevention (TasP) for HIV elimination strategy (2).…”

“…In the end, the authors concluded that the UNAIDS goals for a country like Lesotho, which is geographically rural and rugged with a highly transient population, needs redirection (1). Additional commentary has offered other considerations, such as the extent of antiretroviral therapy coverage in modeling, novel strategies to surmount antiretroviral therapy (ART) delivery and access issues in rural areas, and implementation of other prevention strategies (e.g., community-based testing, partner notification) that may need to be factored into future analyses (4).…”

“…Despite the current debate surrounding the Coburn et al findings for UNAIDS policy and programming (1,4,6), and the implications for how to direct resources across Lesotho's urban and rural areas, we offer our perspective on the perspective on the utility of geospatial modeling. We argue that its value extends well beyond the scope of HIV elimination.…”

“…Instead, Coburn et al propose optimizing the efficiency of the TasPbased elimination strategy by allocating treatment resources based on the geographic dispersion pattern of HIV-positive individuals (i.e., allocating more treatment resources to areas with the highest DOI). Although this is currently a topic of debate, as it would result in considerable variation in coverage between districts, and likely intensify ruralurban health disparities, it would still result in the same overall reduction in the AIDS mortality rate at the national level (1,4,6).…”