title: Soil-transmitted helminthiasis: the relationship between prevalence and classes of intensity of infection.
abstract: BACKGROUND
  Recently, WHO has developed a predictive model to evaluate the impact of preventive chemotherapy programs to control the morbidity of soil-transmitted helminths (STHs). To make predictions, this model needs baseline information about the proportion of infections classified as low, moderate and high intensity, for each of the three STH species. However, epidemiological data available are often limited to prevalence estimates.
  
  
  METHODS
  We reanalyzed available data from 19 surveys in 10 countries and parameterized the relationship between prevalence of STH infections and the proportion of moderate and heavy intensity infections.
  
  
  RESULTS
  The equations derived allow feeding the WHO model with estimates of the proportion of the different classes of infection intensity when only prevalence data is available.
  
  
  CONCLUSIONS
  The prediction capacities of the STH model using the equations developed in the present study, should be tested by comparing it with the changes on STH epidemiological data observed in control programs operating for several years.
authors.affiliation: Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland montresora@who.int.
authors.forename: Antonio
authors.initials: A
authors.lastname: Montresor
authors.affiliation: Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland.
authors.forename: Natacha
authors.initials: N
authors.lastname: À Porta
authors.affiliation: Ivo de Carneri Fondation, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Albonico
authors.affiliation: Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland.
authors.forename: Albis Francesco
authors.initials: AF
authors.lastname: Gabrielli
authors.affiliation: Centre for Health Economics, University of York, York, UK.
authors.forename: Dina
authors.initials: D
authors.lastname: Jankovic
authors.affiliation: Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland.
authors.forename: Christopher
authors.initials: C
authors.lastname: Fitzpatrick
authors.affiliation: Department of Virology, Parasitology and Immunology, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium.
authors.forename: Jozef
authors.initials: J
authors.lastname: Vercruysse
authors.affiliation: Department of Virology, Parasitology and Immunology, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium.
authors.forename: Bruno
authors.initials: B
authors.lastname: Levecke
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D005243:Feces / Q000469:parasitology*; D006373:Helminthiasis / Q000453:epidemiology* / Q000635:transmission*; D006801:Humans; D008390:Markov Chains; D011203:Poverty; D015995:Prevalence; D012720:Severity of Illness Index; D012987:Soil / Q000469:parasitology*; D012988:Soil Microbiology / Q000592:standards*
chemical_list: D000871:Anthelmintics; D012987:Soil
keywords: Epidemiology; Soil-transmitted helminths