title: The impact of an 8-year mass drug administration programme on prevalence, intensity and co-infections of soil-transmitted helminthiases in Burundi.
abstract: BACKGROUND
  Soil-transmitted helminth (STH) infections are amongst the most prevalent infections in the world. Mass drug administration (MDA) programmes have become the most commonly used national interventions for endemic countries to achieve elimination. This paper aims to describe the effect of an 8-year MDA programme on the prevalence, intensity of infection and co-infection of STH in Burundi from 2007 to 2014 and critically appraise the trajectory towards STH elimination in the country.
  
  
  RESULTS
  Annual STH parasitological surveys (specifically, a "pilot study" from 2007 to 2011, an "extension study" from 2008 to 2011, and a "national reassessment" in 2014; n = 27,658 children), showed a significant drop in prevalence of infection with any STH ("pooled STH") between baseline and 2011 in both studies, falling from 32 to 16 % in the pilot study, and from 35 to 16 % in the extension study. Most STH infections were of low intensity according to WHO classification. The national reassessment in 2014 showed that prevalence of pooled STH remained significantly below the prevalence in 2007 in both studies but there was no further decrease in STH prevalence from 2011 levels during this time. Spatial dependence analysis showed that prevalence of Trichuris trichiura and Ascaris lumbricoides had a tendency to cluster over the years, whilst only trends in spatial dependence were evident for hookworm infections. Spatial dependence fluctuated over the course of the programme for Ascaris lumbricoides and Trichuris trichiura. However, spatial trends in spatial dependence were evident in 2010 for Ascaris lumbricoides. Analysis of spatial clustering of intensity of infection and heavy infections revealed that the intensity changed over time for all parasites. Heavy intensity was only evident in Ascaris lumbricoides for 2008 and did not appear in proceeding years and other parasites.
  
  
  CONCLUSIONS
  These results demonstrate that sustained annual MDA significantly reduced the prevalence of STH infection in school-age children but was unable to achieve elimination. Additionally, significant decline in prevalence was accompanied by a drop in spatial clustering of infection indicators across all sites from 2008. The lack of consistency in the results of the spatial dependence analysis highlights that MDA programmes can interrupt the normal transmission dynamics of STH parasites.
authors.affiliation: Schistosomiasis Control Initiative, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK. g.ortu@malariaconsortium.org.
authors.forename: Giuseppina
authors.identifier: http://orcid.org/0000-0001-9437-6524
authors.initials: G
authors.lastname: Ortu
authors.affiliation: School of Medicine, The University of Queensland, Brisbane, Australia.|Children's Health and Environment Program, Child Health Research Centre, The University of Queensland, Brisbane, Australia.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Assoum
authors.affiliation: Schistosomiasis Control Initiative, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK.
authors.forename: Udo
authors.initials: U
authors.lastname: Wittmann
authors.affiliation: Schistosomiasis Control Initiative, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Knowles
authors.affiliation: Schistosomiasis Control Initiative, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Clements
authors.affiliation: Programme National Intégré de lutte contre les Maladies Tropicales Négligées et la Cécité (PNIMTNC) - Ministère de la Santé Publique et de la lutte contre le SIDA, Bujumbura, Burundi.
authors.forename: Onésime
authors.initials: O
authors.lastname: Ndayishimiye
authors.affiliation: Schistosomiasis Control Initiative, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK.|London Centre for Neglected Tropical Disease Research, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK.
authors.forename: Maria-Gloria
authors.initials: MG
authors.lastname: Basáñez
authors.affiliation: Children's Health and Environment Program, Child Health Research Centre, The University of Queensland, Brisbane, Australia.|Research School of Population Health, Australian National University, Canberra, Australia.
authors.forename: Colleen
authors.initials: C
authors.lastname: Lau
authors.affiliation: Research School of Population Health, Australian National University, Canberra, Australia.
authors.forename: Archie
authors.initials: A
authors.lastname: Clements
authors.affiliation: Schistosomiasis Control Initiative, Imperial College London, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St. Mary's Campus), Norfolk Place, London, W2 1PG, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Fenwick
authors.affiliation: Children's Health and Environment Program, Child Health Research Centre, The University of Queensland, Brisbane, Australia.|School of Veterinary Science, The University of Queensland (Gatton Campus), Via Warrego Highway, Gatton, QLD, 4343, Australia.
authors.forename: Ricardo J Soares
authors.initials: RJ
authors.lastname: Magalhaes
keywords: Burundi; Impact; Intensity; Mass drug administration; Prevalence; Soil-transmitted helminth infections; Spatial dependence analysis