11 August 2026
Schistosomiasis is intrinsically linked to water, sanitation, and hygiene (WASH), yet important gaps remain in our understanding of how WASH services, behaviours, and environmental factors affect transmission, according to new research supported by Unlimit Health.
The scoping review, brings together evidence from 181 studies to examine WASH-related risk factors for schistosomiasis and identify where further research is needed to support disease elimination.
While previous research has established clear links between WASH and schistosomiasis, questions remain about how different factors affect specific transmission pathways and how interventions can most effectively contribute to interrupting transmission.
The researchers found a growing body of evidence on WASH access and water-contact behaviours, particularly domestic, recreational, and occupational activities. However, they also identified several important limitations.
Many studies rely on basic measures of access to water and sanitation, without assessing the quality and functionality or consistent use of those services over time. Other potential transmission pathways remain under-investigated, while inconsistent WASH definitions and limited reporting by parasite species and infection intensity make findings difficult to compare across studies.
Among the 21 intervention studies, over 90% reported reductions in infection. However, relatively few assessed whether changes in WASH behaviours and service use were sustained or considered wider environmental impacts.
“As countries move towards elimination, understanding how WASH services affect transmission is more important than ever. The review highlights where evidence is most abundant, and where critical gaps remain,” said Laura Braun, the review’s lead author and Assistant Professor at the London School of Hygiene & Tropical Medicine.
The authors call for future research to adopt standardised WASH definitions and transmission-specific conceptual frameworks, report outcomes by parasite species and infection intensity, and more comprehensively evaluate the quality, functionality, and sustained use of WASH services.
Intervention studies should also examine whether programmes are delivered as intended, whether changes are sustained over time, and whether they achieve sufficient population coverage. Longer-term follow-up will be important for understanding reinfection and determining whether interventions produce lasting reductions in transmission.
Strengthening this evidence base can help countries better understand how WASH can complement preventive chemotherapy and other interventions as part of comprehensive approaches to schistosomiasis elimination.
Citation: Braun L, Velleman Y, Straily A, Secor WE (2026) Water, sanitation, and hygiene in schistosomiasis control: A scoping review of evidence gaps across transmission pathways. PLOS Glob Public Health 6(7): e0006916. https://doi.org/10.1371/journal.pgph.0006916
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