Mapping and Characterising HIV Transmission Hotspots in Sub-Saharan Africa: A Geospatial Analysis of National Survey Data

Abstract

Background: In the generalised epidemics of sub-Saharan Africa (SSA), HIV prevalence shows patterns of clustered micro-epidemics. We mapped and characterised these so-called 'hotspots' for young adults (15-29 years of age), as a proxy for transmission hotspots, for seven countries in Eastern and Southern Africa: Kenya, Malawi, Mozambique, Tanzania, Uganda, Zambia, and Zimbabwe. Methods: We used geolocated survey data and applied kriging to predict HIV prevalence at unmeasured locations. We explored to what extent behavioural, socioeconomic and environmental factors explain HIV prevalence at the individual- and sample location-level, by developing a series of multilevel multivariable logistic regression models. We then compared and geospatially visualised how heterogeneity and hotspots can be explained by the models. Findings: We found clear HIV hotspots among young adults, characterised by areas with prevalences of over 11% or 15% alternating with areas of prevalences between 0% and 2%. Heterogeneity could be explained for 15·6% by an interplay of known behavioural, socioeconomic and environmental factors. Maps of the interpolated random effect estimates show that environmental variables, representing indicators of economic activity, were most powerful in explaining HIV hotspot locations. Interpretation: In young adults, micro-epidemics of relatively high HIV prevalence alternate with areas of very low prevalence, clearly illustrating the existence of transmission hotspots. These hotspots are partially characterised by high economic activity, relatively high socioeconomic status, and risky sexual behaviour. Localised HIV prevention interventions specifically tailored to the populations at risk will be essential to curb transmission. More fine-scale geospatial mapping of key populations, such as sex workers, and migrant populations, could help to further understand the drivers of these transmission hotspots, and to determine to what extent they fuel the generalised epidemics in SSA. Funding Statement: This study was funded by the Dutch AIDS Foundation (P-29702). Furthermore, Jan Hontelez was supported by the NWO Talent Scheme. Till Barnighausen was supported by the Alexander von Humboldt Foundation through the Alexander von Humboldt Professor award, funded by the Federal Ministry of Education and Research; the Wellcome Trust; and from NICHD of NIH (R01-HD084233), NIA of NIH (P01-AG041710), NIAID of NIH (R01-AI124389 and R01-AI112339) as well as FIC of NIH (D43-TW009775). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: Not required.