Modelling the distribution and transmission intensity of lymphatic filariasis in sub-Saharan Africa prior to scaling up interventions: integrated use of geostatistical and mathematical modelling

• Type of Material: Article
• Authors: Paula Moraga, London School of Hygiene & Tropical Medicine; Jorge Cano, London School of Hygiene & Tropical Medicine; Rebecca F. Baggaley, London School of Hygiene & Tropical Medicine; John O. Gyapong, University of Ghana; Sammy M. Njenga, Kenya Medical Research Institute; Birgit Nikolay, London School of Hygiene & Tropical Medicine; Emmanuel Davies, Ministry of Health, Nigeria; Maria Rebollo Polo, Emory University; Rachel L. Pullan, London School of Hygiene & Tropical Medicine; Moses J. Bockarie, Liverpool School for Tropical Medicine; T. Déirdre Hollingsworth, University of Warwick; Manoj Gambhir, Monash University; Simon J. Brooker, London School of Hygiene & Tropical Medicine
• Language: English
• Date: 2015-10-24
• Publisher: BioMed Central
• Publication Version: Final Published Version
• Copyright Statement: © Moraga et al. 2015
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1186/s13071-015-1166-x
• Title of Journal or Parent Work: Parasites and Vectors
• ISSN: 1756-3305
• Volume: 8
• Issue: 1
• Grant/Funding Information: This work received financial support from the Coalition for Operational Research on the NTDs (COR-NTD) which is funded at the Task Force for Global Health by the Bill & Melinda Gates Foundation through its Neglected Tropical Diseases Program.; The Wellcome Trust through a Senior Research Fellowship to SJB (098045), the Bill & Melinda Gates Foundation (OPP1033751), GlaxoSmithKline (JC, SJB, MJB) and the United Kingdom Department for International Development (MPR, MJB) also contributed to this work.
• Keywords: Sub-Saharan Africa; Wuchereria bancrofti; Basic reproductive number; Mathematical modelling; Bayesian geostatistical modelling; Lymphatic filariasis
• Research Categories: Health Sciences, Epidemiology; Biology, Parasitology

Abstract

Background Lymphatic filariasis (LF) is one of the neglected tropical diseases targeted for global elimination. The ability to interrupt transmission is, partly, influenced by the underlying intensity of transmission and its geographical variation. This information can also help guide the design of targeted surveillance activities. The present study uses a combination of geostatistical and mathematical modelling to predict the prevalence and transmission intensity of LF prior to the implementation of large-scale control in sub-Saharan Africa. Methods A systematic search of the literature was undertaken to identify surveys on the prevalence of Wuchereria bancrofti microfilaraemia (mf), based on blood smears, and on the prevalence of antigenaemia, based on the use of an immuno-chromatographic card test (ICT). Using a suite of environmental and demographic data, spatiotemporal multivariate models were fitted separately for mf prevalence and ICT-based prevalence within a Bayesian framework and used to make predictions for non-sampled areas. Maps of the dominant vector species of LF were also developed. The maps of predicted prevalence and vector distribution were linked to mathematical models of the transmission dynamics of LF to infer the intensity of transmission, quantified by the basic reproductive number (R0). Results The literature search identified 1267 surveys that provide suitable data on the prevalence of mf and 2817 surveys that report the prevalence of antigenaemia. Distinct spatial predictions arose from the models for mf prevalence and ICT-based prevalence, with a wider geographical distribution when using ICT-based data. The vector distribution maps demonstrated the spatial variation of LF vector species. Mathematical modelling showed that the reproduction number (R0) estimates vary from 2.7 to 30, with large variations between and within regions. Conclusions LF transmission is highly heterogeneous, and the developed maps can help guide intervention, monitoring and surveillance strategies as countries progress towards LF elimination.