title: Global epidemiology of yaws: a systematic review.
abstract: BACKGROUND
  To achieve yaws eradication, the use of the new WHO strategy of initial mass treatment with azithromycin and surveillance twice a year needs to be extended everywhere the disease occurs. However, the geographic scope of the disease is unknown. We aimed to synthesise published and unpublished work to update the reported number of people with yaws at national and subnational levels and to estimate at-risk populations.
  
  
  METHODS
  We searched PubMed and WHO databases to identify published data for prevalence of active and latent yaws from Jan 1, 1990, to Dec 31, 2014. We also searched for ongoing or recently completed unpublished studies from the WHO yaws surveillance network. We estimated yaws prevalence (and 95% CIs). We collected yaws incidence data from official national surveillance programmes at the first administrative level from Jan 1, 2010, to Dec 31, 2013, and we used total population data at the second administrative level to estimate the size of at-risk populations.
  
  
  RESULTS
  We identified 103 records, of which 23 published articles describing 27 studies and four unpublished studies met the inclusion criteria. Prevalence of active disease ranged from 0·31% to 14·54% in yaws-endemic areas, and prevalence of latent yaws ranged from 2·45% to 31·05%. During 2010-13, 256 343 yaws cases were reported to WHO from 13 endemic countries, all of which are low-income and middle-income countries. 215 308 (84%) of 256 343 cases reported to WHO were from three countries-Papua New Guinea, Solomon Islands, and Ghana. We estimated that, in 2012, over 89 million people were living in yaws-endemic districts.
  
  
  CONCLUSIONS
  Papua New Guinea, Solomon Islands, and Ghana should be the focus of initial efforts at implementing the WHO yaws eradication strategy. Community-based mapping and active surveillance must accompany the implementation of yaws eradication activities.
  
  
  BACKGROUND
  None.
authors.affiliation: Barcelona Institute for Global Health, Barcelona Centre for International Health Research, Hospital Clinic, University of Barcelona, Barcelona, Spain; Lihir Medical Centre-International SOS, Newcrest Mining, Lihir Island, Papua New Guinea. Electronic address: oriol.mitja@isglobal.org.
authors.forename: Oriol
authors.initials: O
authors.lastname: Mitjà
authors.affiliation: Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, UK; Hospital for Tropical Diseases, University College London Hospitals NHS Trust, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Marks
authors.affiliation: Laboratoire Biostatistique et d'Informatique Médicale, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire.
authors.forename: Diby J P
authors.initials: DJ
authors.lastname: Konan
authors.affiliation: Centre de Dépistage et de Traitement de l'Ulcère de Buruli d'Allada, Cotonou, Benin.
authors.forename: Gilbert
authors.initials: G
authors.lastname: Ayelo
authors.affiliation: Barcelona Institute for Global Health, Barcelona Centre for International Health Research, Hospital Clinic, University of Barcelona, Barcelona, Spain.
authors.forename: Camila
authors.initials: C
authors.lastname: Gonzalez-Beiras
authors.affiliation: Programme National de Lutte contre les Maladies Tropicales Négligées, Ministère de la Santé Publique, de la Population et de la Lutte contre le SIDA, Bangui, Central African Republic.
authors.forename: Bernard
authors.initials: B
authors.lastname: Boua
authors.affiliation: Disease Control Branch, National Department of Health, Port Moresby, Papua New Guinea.
authors.forename: Wendy
authors.initials: W
authors.lastname: Houinei
authors.affiliation: Programme National de Lutte contre l'Ulcère de Buruli et la Lèpre, Lomé, Togo.
authors.forename: Yiragnima
authors.initials: Y
authors.lastname: Kobara
authors.affiliation: National Leprosy, Buruli Ulcer, Yaws and Leishmaniasis Control Programme, Ministry of Public Health, Yaoundé, Cameroon.
authors.forename: Earnest N
authors.initials: EN
authors.lastname: Tabah
authors.affiliation: Ghana Health Service, Public Health Division, Accra, Ghana.
authors.forename: Agana
authors.initials: A
authors.lastname: Nsiire
authors.affiliation: Programme National de Lutte contre l'Ulcère de Buruli, Ministère de la Santé Publique, Brazzaville, Congo.
authors.forename: Damas
authors.initials: D
authors.lastname: Obvala
authors.affiliation: Neglected Tropical Diseases Program, Public Health Directorate, Health Department, Port Vila, Vanuatu.
authors.forename: Fasiah
authors.initials: F
authors.lastname: Taleo
authors.affiliation: National Leprosy and Yaws Programme, Ministry of Health, Jakarta, Indonesia.
authors.forename: Rita
authors.initials: R
authors.lastname: Djupuri
authors.affiliation: World Health Organization Country Office, Honiara, Solomon Islands; WHO Country Office, Manila, Philippines.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Zaixing
authors.affiliation: Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.
authors.forename: Jürg
authors.initials: J
authors.lastname: Utzinger
authors.affiliation: World Health Organization Regional Office for the Western Pacific, Manila, Philippines.
authors.forename: Lase S
authors.initials: LS
authors.lastname: Vestergaard
authors.affiliation: Barcelona Institute for Global Health, Barcelona Centre for International Health Research, Hospital Clinic, University of Barcelona, Barcelona, Spain.
authors.forename: Quique
authors.initials: Q
authors.lastname: Bassat
authors.affiliation: Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland.
authors.forename: Kingsley
authors.initials: K
authors.lastname: Asiedu
mesh_terms: D003906:Developing Countries; D019353:Endemic Diseases; D005869:Ghana / Q000453:epidemiology; D014943:Global Health; D006801:Humans; D007182:Income; D008542:Melanesia / Q000453:epidemiology; D010219:Papua New Guinea; D015001:Yaws / Q000453:epidemiology*