PLoS Neglected Tropical Diseases (Feb 2023)

Exploring water, sanitation, and hygiene coverage targets for reaching and sustaining trachoma elimination: G-computation analysis

  • Kristin M. Sullivan,
  • Emma M. Harding-Esch,
  • Alexander P. Keil,
  • Matthew C. Freeman,
  • Wilfrid E. Batcho,
  • Amadou A. Bio Issifou,
  • Victor Bucumi,
  • Assumpta L. Bella,
  • Emilienne Epee,
  • Segni Bobo Barkesa,
  • Fikre Seife Gebretsadik,
  • Salimato Sanha,
  • Khumbo M. Kalua,
  • Michael P. Masika,
  • Abdallahi O. Minnih,
  • Mariamo Abdala,
  • Marília E. Massangaie,
  • Abdou Amza,
  • Boubacar Kadri,
  • Beido Nassirou,
  • Caleb D. Mpyet,
  • Nicholas Olobio,
  • Mouctar D. Badiane,
  • Balgesa E. Elshafie,
  • Gilbert Baayenda,
  • George E. Kabona,
  • Oscar Kaitaba,
  • Alistidia Simon,
  • Tawfik Q. Al-Khateeb,
  • Consity Mwale,
  • Ana Bakhtiari,
  • Daniel Westreich,
  • Anthony W. Solomon,
  • Emily W. Gower

Journal volume & issue
Vol. 17, no. 2

Abstract

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Background Trachoma is the leading infectious cause of blindness. To reduce transmission, water, sanitation, and hygiene (WaSH) improvements are promoted through a comprehensive public health strategy. Evidence supporting the role of WaSH in trachoma elimination is mixed and it remains unknown what WaSH coverages are needed to effectively reduce transmission. Methods/Findings We used g-computation to estimate the impact on the prevalence of trachomatous inflammation—follicular among children aged 1–9 years (TF1-9) when hypothetical WaSH interventions raised the minimum coverages from 5% to 100% for “nearby” face-washing water (Conclusions Our results support Sustainable Development Goal 6 and provide insight into potential WaSH-related coverage targets for trachoma elimination. Targets can be tested in future trials to improve evidence-based WaSH guidance for trachoma. Author summary Previous work has been unable to determine what water, sanitation, and hygiene (WaSH)-related coverages are needed to optimally limit trachoma transmission. This study uses a large, multi-national dataset to explore the impact of hypothetical WaSH interventions designed to increase coverages of face-washing water and latrine use in districts that have met and those that have not met trachoma elimination targets. We used statistical models to explore how these interventions impacted the prevalence of trachoma among children as compared to the observed data. Our findings provide evidence-based insight into potential WaSH coverage targets that could be hypothesized to achieve meaningful reductions in trachoma prevalence. We found that in areas working to reach trachoma elimination targets, increasing face-washing water and latrine use coverages to a minimum of ≥30% were consistently associated with (modelled) reductions in active trachoma prevalence. However, in areas that had already met trachoma elimination targets, we did not see the same pattern. This finding supports our theory that the WaSH-trachoma relationship differs in these areas and suggests a need for additional research to explore these relationships. Our estimates can be used to inform programmatic WaSH targets and future field trials.