title: How effective is school-based deworming for the community-wide control of soil-transmitted helminths?
abstract: BACKGROUND
  The London Declaration on neglected tropical diseases was based in part on a new World Health Organization roadmap to "sustain, expand and extend drug access programmes to ensure the necessary supply of drugs and other interventions to help control by 2020". Large drug donations from the pharmaceutical industry form the backbone to this aim, especially for soil-transmitted helminths (STHs) raising the question of how best to use these resources. Deworming for STHs is often targeted at school children because they are at greatest risk of morbidity and because it is remarkably cost-effective. However, the impact of school-based deworming on transmission in the wider community remains unclear.
  
  
  METHODS
  We first estimate the proportion of parasites targeted by school-based deworming using demography, school enrolment, and data from a small number of example settings where age-specific intensity of infection (either worms or eggs) has been measured for all ages. We also use transmission models to investigate the potential impact of this coverage on transmission for different mixing scenarios.
  
  
  RESULTS
  In the example settings <30% of the population are 5 to <15 years old. Combining this demography with the infection age-intensity profile we estimate that in one setting school children output as little as 15% of hookworm eggs, whereas in another setting they harbour up to 50% of Ascaris lumbricoides worms (the highest proportion of parasites for our examples). In addition, it is estimated that from 40-70% of these children are enrolled at school.
  
  
  CONCLUSIONS
  These estimates suggest that, whilst school-based programmes have many important benefits, the proportion of infective stages targeted by school-based deworming may be limited, particularly where hookworm predominates. We discuss the consequences for transmission for a range of scenarios, including when infective stages deposited by children are more likely to contribute to transmission than those from adults.
authors.affiliation: London Centre for Neglected Tropical Diseases, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom. roy.anderson@imperial.ac.uk
authors.forename: Roy M
authors.initials: RM
authors.lastname: Anderson
authors.forename: James E
authors.initials: JE
authors.lastname: Truscott
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Pullan
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Brooker
authors.forename: T Deirdre
authors.initials: TD
authors.lastname: Hollingsworth
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003140:Communicable Disease Control / Q000379:methods; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D005260:Female; D006302:Health Services Research; D006373:Helminthiasis / Q000188:drug therapy* / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D006801:Humans; D008131:London / Q000453:epidemiology; D008297:Male; D016896:Treatment Outcome
chemical_list: D000871:Anthelmintics