Development, field-testing and optimization of tools to quantify soil-transmitted helminths in fecal sludge from school pit latrines in Ethiopia
8 affiliations
- 1School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
- 2Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke-Melle, Belgium
- 3Environmental Health and Ecological Science Department, Ifakara Health Institute, Dar es Salaam, Tanzania
- 4Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada
- 5Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom
- 6Department of Health, Behavior, and Society, Institute of Health, Jimma University, Jimma, Ethiopia
- 7Microvida Laboratory for Medical Microbiology and Immunology, Elisabeth Tweesteden Hospital, Tilburg, The Netherlands
- 8Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
Abstract
Background: Surveys to monitor large-scale deworming programs against soil-transmitted helminthiases (STH) involve collection and examination of stool samples from schoolchildren. These surveys are resource demanding and interrupt school activities. A potentially cost-saving alternative that does not involve children is to process fecal sludge samples from school pit latrines. As a first step towards a proof-of-principle of latrine-based monitoring of STH programs, we optimized tools to collect fecal sludge and to quantify STH eggs in the samples. Methods: First, we developed and field-tested three locally made fecal sludge sampling prototypes. Second, we developed a modified egg counting method and conducted spiking experiments to explore its analytical performance. Third, we estimated the variation in egg counts in fecal sludge samples that were collected from six primary schools in Ethiopia at different pit latrine depths used by boys and girls and that were repeatedly examined. Finally, field data was used to inform an egg count simulation model to quantify the variation in egg counts and to determine the sampling and analysis strategies that resulted in surveys as precise as stool-based surveys. Results: The modified fecal sludge sampling prototypes were generally successful, except for a few pit latrines with dried/solid fecal sludge and insufficient sludge volume. The egg counting method had moderately high analytical sensitivity that varied across the consistency of the samples and examination effort. The variation in egg counts was mainly explained by differences between squat holes followed by repeated fecal sludge sample processing. Latrine-based surveys were as precise as stool-based surveys only for Ascaris and when the intensity of infections was low. Conclusions: We developed a sampling and diagnostic strategy that we will use in a follow-up study which will be conducted in Jimma Zone across 25 schools (52 children per school) and will compare the mean fecal sludge egg counts at school level with the STH prevalence in children. Author summary: Progress of large-scale deworming programs are currently monitored through screening individual stool samples of schoolchildren. A latrine-based survey, without active participation of schoolchildren and interruption of routine school activities, is a potentially cost-effective alternative. As a proof-of-concept, we developed a method to quantify worm eggs in fecal sludge samples, conducted spiking experiments to determine its analytical performance and applied the method across schools in Ethiopia to explore variation in egg counts (e.g., squat holes, depth of sample collection, and repeated analyses). Based on our findings, we then determined the sample collection and laboratory analysis strategy that results in a latrine-based survey as precise as a survey based on screening individual stool samples. The analytical performance was moderately high but varied across the consistency of the samples and diagnostic efforts. The variation in egg counts was mainly driven by variation between squat holes on the same pit latrine, and thus it is better to sample more squat holes than repeatedly processing the same fecal sludge sample. We will now apply this sample collection and analysis across 25 schools (52 children per school) in Ethiopia and compare it with a survey based on screening individual stool samples.
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BibTeX
@article{tiruneh2026development,
title = {{Development, field-testing and optimization of tools to quantify soil-transmitted helminths in fecal sludge from school pit latrines in Ethiopia}},
author = {Abebaw Tiruneh and Zeleke Mekonnen and Sara Roose and Mio Ayana and Fiona Vande Velde and Emmanuel C. Mrimi and John S. Gilleard and Michael R. Templeton and Zewdie Birhanu and Jaco J. Verweij and Luc E. Coffeng and Bruno Levecke},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = sep,
doi = {10.1371/journal.pntd.0014724},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014724},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Development, field-testing and optimization of tools to quantify soil-transmitted helminths in fecal sludge from school pit latrines in Ethiopia
AU - Abebaw Tiruneh
AU - Zeleke Mekonnen
AU - Sara Roose
AU - Mio Ayana
AU - Fiona Vande Velde
AU - Emmanuel C. Mrimi
AU - John S. Gilleard
AU - Michael R. Templeton
AU - Zewdie Birhanu
AU - Jaco J. Verweij
AU - Luc E. Coffeng
AU - Bruno Levecke
PY - 2026
DA - 2026/09/15
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0014724
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014724
AB - Background: Surveys to monitor large-scale deworming programs against soil-transmitted helminthiases (STH) involve collection and examination of stool samples from schoolchildren. These surveys are resource demanding and interrupt school activities. A potentially cost-saving alternative that does not involve children is to process fecal sludge samples from school pit latrines. As a first step towards a proof-of-principle of latrine-based monitoring of STH programs, we optimized tools to collect fecal sludge and to quantify STH eggs in the samples. Methods: First, we developed and field-tested three locally made fecal sludge sampling prototypes. Second, we developed a modified egg counting method and conducted spiking experiments to explore its analytical performance. Third, we estimated the variation in egg counts in fecal sludge samples that were collected from six primary schools in Ethiopia at different pit latrine depths used by boys and girls and that were repeatedly examined. Finally, field data was used to inform an egg count simulation model to quantify the variation in egg counts and to determine the sampling and analysis strategies that resulted in surveys as precise as stool-based surveys. Results: The modified fecal sludge sampling prototypes were generally successful, except for a few pit latrines with dried/solid fecal sludge and insufficient sludge volume. The egg counting method had moderately high analytical sensitivity that varied across the consistency of the samples and examination effort. The variation in egg counts was mainly explained by differences between squat holes followed by repeated fecal sludge sample processing. Latrine-based surveys were as precise as stool-based surveys only for Ascaris and when the intensity of infections was low. Conclusions: We developed a sampling and diagnostic strategy that we will use in a follow-up study which will be conducted in Jimma Zone across 25 schools (52 children per school) and will compare the mean fecal sludge egg counts at school level with the STH prevalence in children. Author summary: Progress of large-scale deworming programs are currently monitored through screening individual stool samples of schoolchildren. A latrine-based survey, without active participation of schoolchildren and interruption of routine school activities, is a potentially cost-effective alternative. As a proof-of-concept, we developed a method to quantify worm eggs in fecal sludge samples, conducted spiking experiments to determine its analytical performance and applied the method across schools in Ethiopia to explore variation in egg counts (e.g., squat holes, depth of sample collection, and repeated analyses). Based on our findings, we then determined the sample collection and laboratory analysis strategy that results in a latrine-based survey as precise as a survey based on screening individual stool samples. The analytical performance was moderately high but varied across the consistency of the samples and diagnostic efforts. The variation in egg counts was mainly driven by variation between squat holes on the same pit latrine, and thus it is better to sample more squat holes than repeatedly processing the same fecal sludge sample. We will now apply this sample collection and analysis across 25 schools (52 children per school) in Ethiopia and compare it with a survey based on screening individual stool samples.
SN - 1935-2735
ER -