Detailed description of data and methods.

Text A. Data description and pre-control data selection criteria. Text B. Parasitological survey methods and geographical limits of the mapping. Text C. Processing of environmental covariates. Text D. Maps of environmental covariates. Text E. K-folds model validation. Text F. MCMC chain diagnostics. Text G. Posterior distributions of model parameters. Text H. Further maps derived from the predictive posterior distributions. Text I. Geospatial software. Table A. Population growth rates, factor by which the 1990 population count was multiplied for back-calculation to 1975, and proportion of the population aged 0–4 years for OCP countries. Fig A. Village locations in the OCP epidemiological database. Fig B. Location of the data points selected for use in this study after applying pre-control selection criteria. Fig C. Scatterplot of age- and sex-standardised microfilarial prevalence in those aged 5 years and above (Pmf), against the crude, unadjusted prevalence. Fig D. Heatmap of distance (in Km) to nearest pre-control survey data point for each map pixel in the study area. Fig E. Lambert Azimuthal Equal Area projection of the world, centred on Africa. Fig F.1. Maps for covariate values at prediction locations, for NDVI βj covariates included in the final predictive model. Fig F.2. Maps for covariate values at prediction locations, for all other βj covariates included in the final predictive model. Fig G. The location of validation points in each K-fold cross-validation dataset. Fig H. MCMC traceplots of all βj regression coefficients. Fig I. MCMC traceplot of the value of the range parameter, ϕ. Fig J. Highest posterior density (HPD) plots of model parameters. Fig K. Mean of predictive posterior distributions for estimated microfilarial prevalence of Onchocerca volvulus prior to the commencement of the Onchocerciasis Control Programme in West Africa (OCP) in 1975. Fig L. Signal to noise ratio between mean and standard deviation of predictive posteriors. Fig M. Histogram of model output mean (left) and median (right) microfilarial prevalence values at all prediction locations.
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