Beyond the tap: rethinking WASH for schistosomiasis control

Schistosomiasis remains one of the most persistent neglected tropical diseases. It affects millions of people who rely on freshwater sources for their daily lives, which is why access to reliable water, sanitation and hygiene (WASH) services is essential. However, infrastructure alone is not enough. Sustainable progress depends on understanding local transmission pathways, addressing environmental risks, and empowering communities to lead solutions. 

Why WASH matters for schistosomiasis control 

In places where sanitation is inadequate, parasite eggs can contaminate freshwater sources. People are exposed to infection when they come into contact with this water during everyday activities such as drinking, laundry, bathing, fishing, farming and swimming. 

Access to, and use of, reliable, high-quality WASH services are therefore fundamental to controlling and eliminating the disease. Nonetheless, standard WASH programmes alone are often not enough to stop transmission. 

In many endemic areas, the disease continues to spread due to a range of environmental and behavioural factors. This can include water management, the use of human waste and wastewater in agriculture, the presence of animals, and frequent contact with surface water for work, recreation or cultural purposes.  

Although preventive chemotherapy with praziquantel is effective for treating schistosomiasis and reducing illness, treatment alone does not prevent reinfection when the parasites and their snail vector persist in the environment. Mass treatment campaigns are mainly conducted among the school-aged population, while young children and adults remain largely untreated. This means transmission can continue, even where regular treatment campaigns are conducted.  

What the evidence tells us 

A new 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. 

The body of evidence comes mainly from observational studies focused on prevalence estimates, rather than directly assessing WASH-related risk factors and their impact on transmission. For example, most studies do not address how the disease is transmitted. They may include WASH variables that are not necessarily risk factors (e.g., linking treated drinking water to schistosome infection) and fail to address all likely sources of infection. Many studies focus on whether water and sanitation facilities exist, rather than whether people can access and use them regularly.   

Most observational studies assessed both infection intensity and prevalence; however, only 12% analysed the relationship between infection intensity (measured by egg counts) and WASH-related factors. This is important because infection intensity affects both the severity of disease and the levels of ongoing transmission.  

The pathway most frequently studied was access to an improved water source (50%), which largely focused on the ‘most frequently used’, but often overlooked people’s contact with other water sources, including potentially contaminated surface water.  

In terms of understanding environmental and behavioural risk factors, the main knowledge gaps include the role that animals play in schistosomiasis transmission; how sanitation-related behaviours and practices affect transmission, such as the use of untreated faecal waste in agriculture; and the role of water treatment in risk reduction.  

How a community-led project is putting evidence into action in Uganda  

Since July 2020, Unlimit Health has been collaborating with partners on a schistosomiasis risk-reduction project in high-prevalence communities in Kamuli District, eastern Uganda. Working closely with the community, project partners gathered local evidence to understand where the schistosomiasis risk was coming from, who was most at risk, and which everyday activities were driving transmission. Together, communities and partners used these insights to develop action plans that reflected the local needs and realities.  

This community-led approach is central to the project’s success. Schistosomiasis has been a persistent public health problem for millennia because its transmission is closely linked to the activities people rely on for their livelihoods and daily lives, as well as their interaction with the environment. Sustainable disease prevention must therefore be shaped by community needs and preferences, as well as their socio-economic circumstances. This process has resulted in a clear plan that includes both the communities’ roles and responsibilities, and the water and health services they are entitled to and willing to pay for, from public service providers.    

The project also recognises that infrastructure alone is not enough. The existence of taps or toilets does not guarantee they will be used or maintained. Communities play a vital role in creating demand for services, using them, and where needed, paying for services to ensure their viability. They can also play a fundamental role in addressing transmission pathways that are not covered by WASH services, such as managing water bodies to reduce snail populations and practicing safe water treatment, bathing, laundry, farming and fishing. Local expertise is invaluable in identifying solutions that are practical and most likely to last. 

Why is this important now? 

Community-driven approaches take time and a real commitment to working with, and listening to, those most affected. They often require agencies and ministries to work together in new ways, which can be challenging.  While these approaches may involve higher upfront costs and longer timeframes, they are more likely to deliver sustainable results because they are built around what communities actually want and need.  

The recent scoping review shows that schistosomiasis transmission is complex and varies across contexts. It also highlights that there is limited evidence on which WASH factors or interventions are most effective at interrupting transmission, so future research should focus on specific areas that are currently under-investigated.  

This reinforces the need to understand local transmission pathways when developing disease prevention strategies. The Uganda project is a strong example of how evidence, combined with community knowledge, can inform the most practical actions that deliver lasting improvements to health.