title: Water, Sanitation and Hygiene (WASH) and environmental risk factors for soil-transmitted helminth intensity of infection in Timor-Leste, using real time PCR.
abstract: No investigations have been undertaken of risk factors for intensity of soil-transmitted helminth (STH) infection in Timor-Leste. This study provides the first analysis of risk factors for intensity of STH infection, as determined by quantitative PCR (qPCR), examining a broad range of water, sanitation and hygiene (WASH) and environmental factors, among communities in Manufahi District, Timor-Leste.
  
  
  
  A baseline cross-sectional survey of 18 communities was undertaken as part of a cluster randomised controlled trial, with additional identically-collected data from six other communities. qPCR was used to assess STH infection from stool samples, and questionnaires administered to collect WASH, demographic, and socioeconomic data. Environmental information was obtained from open-access sources and linked to infection outcomes. Mixed-effects multinomial logistic regression was undertaken to assess risk factors for intensity of Necator americanus and Ascaris infection.
  
  
  
  2152 participants provided stool and questionnaire information for this analysis. In adjusted models incorporating WASH, demographic and environmental variables, environmental variables were generally associated with infection intensity for both N. americanus and Ascaris spp. Precipitation (in centimetres) was associated with increased risk of moderate-intensity (adjusted relative risk [ARR] 6.1; 95% confidence interval [CI] 1.9-19.3) and heavy-intensity (ARR 6.6; 95% CI 3.1-14.1) N. americanus infection, as was sandy-loam soil around households (moderate-intensity ARR 2.1; 95% CI 1.0-4.3; heavy-intensity ARR 2.7; 95% CI 1.6-4.5; compared to no infection). For Ascaris, alkaline soil around the household was associated with reduced risk of moderate-intensity infection (ARR 0.21; 95% CI 0.09-0.51), and heavy-intensity infection (ARR 0.04; 95% CI 0.01-0.25). Few WASH risk factors were significant.
  
  
  
  In this high-prevalence setting, strong risk associations with environmental factors indicate that anthelmintic treatment alone will be insufficient to interrupt STH transmission, as conditions are favourable for ongoing environmental transmission. Integrated STH control strategies should be explored as a priority.
authors.affiliation: Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, Acton, Australian Capital Territory, Australia.
authors.forename: Suzy J
authors.identifier: 0000-0001-5540-1360
authors.initials: SJ
authors.lastname: Campbell
authors.affiliation: Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, Acton, Australian Capital Territory, Australia.
authors.forename: Susana V
authors.initials: SV
authors.lastname: Nery
authors.affiliation: Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, Acton, Australian Capital Territory, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Wardell
authors.affiliation: Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, Acton, Australian Capital Territory, Australia.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: D'Este
authors.affiliation: Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, Acton, Australian Capital Territory, Australia.|Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.|School of Public Health, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Gray
authors.affiliation: School of Public Health, University of Queensland, Brisbane, Queensland, Australia.|Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: James S
authors.initials: JS
authors.lastname: McCarthy
authors.affiliation: Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Traub
authors.affiliation: Menzies School of Health Research, Charles Darwin University, Casuarina, Northern Territory, Australia.
authors.forename: Ross M
authors.initials: RM
authors.lastname: Andrews
authors.affiliation: Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Stacey
authors.initials: S
authors.lastname: Llewellyn
authors.affiliation: Kirby Institute, University of New South Wales, Wallace Wurth Building, Kensington, New South Wales, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Vallely
authors.affiliation: School of Public Health, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Gail M
authors.initials: GM
authors.lastname: Williams
authors.affiliation: Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, Acton, Australian Capital Territory, Australia.
authors.forename: Archie C A
authors.initials: AC
authors.lastname: Clements
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D005243:Feces / Q000469:parasitology; D005260:Female; D006373:Helminthiasis / Q000453:epidemiology*; D006376:Helminths / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D006920:Hygiene; D007223:Infant; D007411:Intestinal Diseases, Parasitic / Q000453:epidemiology*; D008297:Male; D008685:Meteorological Concepts; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors; D012499:Sanitation / Q000379:methods*; D012987:Soil / Q000737:chemistry; D011795:Surveys and Questionnaires; D049648:Timor-Leste / Q000453:epidemiology; D014871:Water Microbiology; D055815:Young Adult
chemical_list: D012987:Soil