Soares Magalhaes, University of Queensland School of Veterinary Science, AUSTRALIA PLoS Negl Trop Dis 10(1):Įditor: Ricardo J. (2016) Model-Based Geostatistical Mapping of the Prevalence of Onchocerca volvulus in West Africa. We present the first pre-control Bayesian geostatistical map of infection (microfilarial) prevalence in the OCP with the objectives of: a) identifying important environmental covariates which help to estimate prevalence in areas without observed survey data b) understanding the distribution of areas of initially high endemicity, where the current CDTI strategy may be insufficient to achieve elimination goals and intensified CDTI or novel/complementary tools may be required c) re-estimating the initial numbers of persons at-risk and with onchocerciasis in 1975.Ĭitation: O’Hanlon SJ, Slater HC, Cheke RA, Boatin BA, Coffeng LE, Pion SDS, et al. The level of endemicity (measured as infection prevalence) prior to control interventions has been shown to be an important determinant of the feasibility of elimination by CDTI. Currently, national control programmes in the former OCP and the World Health Organization African Programme for Onchocerciasis Control (APOC) are shifting their focus from morbidity control to elimination of the infection where feasible through community-directed treatment with ivermectin (CDTI). Operational between 19, the Onchocerciasis Control Programme in West Africa (OCP) was one of the first large-scale intervention programmes ever implemented, and was successful in controlling the disease as a problem of public health importance. Onchocerciasis is a neglected tropical disease caused by Onchocerca volvulus and transmitted by Simulium blackflies. Within OCP boundaries, 17.8 million people were deemed to have been at risk, 7.55 million to have been infected, and mean microfilarial prevalence to have been 45% (range: 2–90%) in 1975. The mean Pearson’s correlation between observed and estimated prevalence at validation locations was 0.693 the mean prediction error (average difference between observed and estimated values) was 0.77%, and the mean absolute prediction error (average magnitude of difference between observed and estimated values) was 12.2%. Uncertainty in model predictions was measured using a suite of validation statistics, performed on bootstrap samples of held-out validation data. These 737 data points, plus a set of statistically selected environmental covariates, were used in a Bayesian model-based geostatistical (B-MBG) approach to generate a continuous surface (at pixel resolution of 5 km x 5km) of microfilarial prevalence in West Africa prior to the commencement of the OCP. Pre-control microfilarial prevalence data from 737 villages across the 11 constituent countries in the OCP epidemiological database were used as ground-truth data.
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