Community Assessments of Socio-economic Constraints for Schistosomiasis Control: A Case Study from Misungwi District, Tanzania

Justina Mosha and Teckla Angelo, National Institute for Medical Research, Mwanza, Tanzania 07/09/2018

One of the main objectives of the Water Infrastructure for Schistosomiasis-Endemic Regions (WISER) Project is to identify the society at risk for schistosomiasis transmission and assess the water contact practices taking place within endemic settings.  Community surveys were conducted in Misungwi district, Tanzania from 26th June to 31st July 2018. The aim was to collect primary data to assess the socioeconomic impact of schistosomiasis transmission in four selected communities namely Mwakalima, Nyang’holongo, Chole and Kigongo from Misungwi district, Mwanza region, Tanzania. Study participants were from the Sukuma ethnic group and their age ranged from 20-55 years. The villages lie along Lake Victoria. Fishing along the lake is one of the major sources of income generation for inhabitants of these communities. Community members also practice subsistence farming for food and cash crops. Crops like maize, sweet potatoes and rice serve as food crops while cotton is a cash crop.

The study used both qualitative (interviews) and quantitative (questionnaires) methods to obtain in-depth insight on people’s knowledge, perceptions and attitudes towards schistosomiasis. Socio-demographic characteristics of the recruited participants were analysed. The willingness of people to participate in initiatives for schistosomiasis control was also explored.

Data were collected by seven well-trained research assistants; five applied the quantitative method and two used the qualitative method. All interviews were conducted in Swahili. This allowed open communication and enabled participants to express their responses reasonably well and also freely give their views.

One of the male Focus Group Discussions (Chole village)

One of the male Focus Group Discussions (Chole village)

Consent to record the discussions and interviews were sought prior to the beginning of the session. Participants were given unique numbers and no personal identifiers were used in the study forms to ensure confidentiality. Participants were randomly selected from the identified communities to be interviewed.

A Research assistant administering a quantitative questionnaire to a female participant at Kigongo village

A Research assistant administering a quantitative questionnaire to a female participant at Kigongo village

One of the Interviews with Key Informant (A member of village committee Nyangh’olongo Village)

One of the Interviews with Key Informant (A member of village committee Nyangh’olongo Village)

The majority of participants were aware of the existence of schistosomiasis in their communities and were able to mention other diseases affecting them. For instance some participants pointed out schistosomiasis symptoms like passing blood in urine. They admitted to neither visiting health facilities for checkups nor taking any kind of medicine due to the long distance to these facilities and poverty. Generally the disease was viewed as a part of their life and a cause for poor health in children. Most of the interviewees also complained about lacking clean water sources in their local settings. Participants suggested that provision of safe and clean water for their daily activities in their communities will reduce schistosomiasis transmission.

Participants are in a great need of alternative ways to survive and rescue their life from schistosomiasis, since the main economic activities fishing and rice cultivation involves water contact.

The full findings of this study will be published at a later date.

Community Case Studies - The task ahead for WISER


A major outcome of the WISER project is to design guidelines and recommend appropriate, sustainable, affordable and equitable water infrastructure in partnership with the communities. Participation and ownership by the communities and individuals most affected by schistosomiasis, poverty and other developmental issues are very important. We cannot underestimate the power of adequate and robust stakeholder engagement by all parties – communities, Government, NGOs, schools etc. It is almost certain that risk and behavioural change communication will be crucial alongside other important factors: social and cultural beliefs, costs, maintenance requirements, local education and training needs, gender and class equity issues. Hence, the words we use with the community needs to be cautiously crafted in clear and understandable terms.

Two global conferences in particular over the past 20 years have helped create and shape the direction of Social and Behavioural Change Communication SBCC - the 1997 Bellagio Conference on Communication and Social Change and the 2006 World Congress on Communication for Development. The practice and systems of communications have the power to transform lives, and to influence the behaviour of institutions, communities and nations. Communities must therefore play an essential role in finding their own communication solutions and developing their own communication strategies. The images and stories that define and shape a group, a community or a people are primarily theirs alone to make. Successfully documented projects show how marginalized people, given the opportunity, can create solutions for complex problems, and often possess the energy and vision that will help ensure the best outcome.

The aim of Objective 3 of WISER is to engage communities through case studies in Ethiopia and Tanzania so as to consider the critical practical non-technical (e.g. socio-economic, cultural) challenges to address when applying the water treatment processes and biosensors for effective intervention. The WISER team visited one of the case study communities, Chole Isamilo near Mwanza, Tanzania on 26th of April 2018. The community, situated on the bank of Lake Victoria, was conducting their normal daily activities (occupational and domestic) without any apparent concern about the potential for the water to be contaminated with schistosome cercariae. Perhaps they have no choice, having no alternative water source, or maybe, they lack awareness regarding the disease burden of schistosomiasis. Perhaps their only source of income is occupational fishing. How do we communicate the risk to such communities? How do we fully engage them? One potential way is through role play. It is evident that “When you create a story with a community, and they see or hear people like themselves acting it out, the message resonates more deeply". Our community stakeholders generally want to lead happy and productive lives that improve themselves, their children and their communities.

pic 16.jpg

During the First Dissemination and Stakeholder Engagement Workshop held on the 24th (Addis) and 27th (Mwanza) of April 2018, we had a session which specifically targeted community representatives from all the case study communities. Some local officials were also in attendance and we had well over 80 people in total for both sessions led by Acting for Health. Volunteers amongst the community members staged role plays, and some important themes began to emerge during the course of the session. These included: complexes and problems associated with schistosomiasis including stigma; obstacles including distance to accessing health services; moral and cultural/traditional beliefs causing parents to refuse medication for children; delaying treatment due to poverty; believing praziquantel to be responsible for lower sex drive/reproduction among men; alternative traditional medicine etc. At the end of the session, the representatives were asked how far in the future they thought schistosomiasis could be eliminated. Their general response was – “It is difficult to say in terms of years because of how our daily routine is so related with contact with the contaminated water body”. But on a positive note, they felt that proper and continued education on the relationship between schistosomiasis and water contact, provision of alternative water supplies, adequate sanitation, and availability of chemotherapy, as well as the willingness of parents to seek hospital medical help instead of traditional treatment, will all greatly help. Some also felt that the use of personal protective equipment for fishermen (e.g. boots and gloves to minimise occupational water contact), with the right messaging, could be helpful. All in all, it was an excellent session that gave us some initial insight into the huge but possible task of eliminating schistosomiasis.       

A great example of WISER’s early positive impact through stakeholder engagement is the changes adopted by a local NGO - Cheka Sana Tanzania - that works on supporting Street Involved Children, Youth and their families in Mwanza.  For a long time, during outreach work, children were taken to a place along Lake Victoria - known as Kigoto, to have a wash and improve their personal hygiene. By the time WISER started interacting with Cheka Sana, coupled with an increase in schistosomiasis cases amongst the children with whom they were involved with, Cheka Sana built an alternative washing facility in their Day centre which is now available for the children to use. They no longer take the children to the lake to wash. This is a great example of how adequate stakeholder engagement can influence policy and change behaviours positively. Although it has been difficult to stop some of the children who still go into the lake for leisure, we will look at how we can further liaise with the organisation to engage the kids and build their understanding of behavioural risks associated with water contact and schistosomiasis. Communicating the risk of exposure due to water contact with contaminated sources like Lake Victoria is very important for meaningful progress.

Now what next? We will work with the case study communities in assessing their knowledge of schistosomiasis and relationship to water (water contact), attitudes and perceptions towards the various strategies for controlling schistosomiasis, willingness to adopt potential interventions such as safe alternative water supplies or protective equipment, ownership and willingness to contribute to maintenance and sustainability of an alternative water supply, if applicable, as well as different approaches to behavioural change and attitudes.

Water treatment for schistosomiasis endemic regions: the role of water infrastructure in reducing transmission and reinfection following chemotherapy

Laura Braun, Imperial College London, 21/2/2018

Since the first full description of the schistosome lifecycle in 1908, the focus of control programs has shifted between different interventions (1). Initially, control measures focused on mollusciciding and preventing contact with contaminated water (2). The enthusiasm for snail control led to the development of molluscicides (3). The research on water treatment and snail control was slowed by the development of effective orally-administered drugs in the late 1970’s (3, 4). Ever since, chemotherapy has been the focus of schistosomiasis control programs (5). Although praziquantel is effective, safe, and inexpensive, the treatment does not prevent subsequent re-infection. As schistosomiasis control targets become more ambitious and move towards elimination, interest is again increasing in the potentially complementary roles of water, sanitation, and hygiene (WASH) interventions which may disrupt transmission of the parasite, thereby reducing reinfection following treatment.

The options for providing safe water (safe meaning free of viable schistosome cercariae) are either treating the water, or providing an alternate safe source of water (such as boreholes or rainwater). In endemic regions, there is often no safe alternative water source, and hence water treatment is required to provide a safe water supply. Water infrastructure must provide water for domestic activities such as washing, laundry, and bathing - activities which are associated with long water-contact periods and therefore risk of exposure to cercariae. Exposure while drinking water is not the main concern when it comes to schistosomiasis, though of course safe drinking water must also be provided in many cases.

There are numerous challenges with implementing water treatment infrastructure. The first is that there are no robust, evidence-based guidelines on how to effectively design water treatment processes to remove or inactivate cercariae. A recently completed systematic review confirmed that there is no consistent, complete data that could be used to design a reliable water treatment infrastructure. The review focused on five water treatment methods – storage, heating, chlorination, filtration and ultraviolet disinfection, all of which have been previously used as water treatment in developing countries and which have shown to be effective against schistosome cercariae to varying degrees, though these previous studies used different experimental protocols for the application of the water treatment processes and for measuring cercaria viability. Our WISER project aims to generate robust, reproducible water treatment data that can be developed into guidelines, for example to say what minimum sand grain size and bed depth effectively filter out cercariae from water.

Although water treatment infrastructure can provide safe water for many household activities, it will not prevent all contact with contaminated water. Occupational activities such as fishing rely on contact with natural water bodies, and exposure to contaminated water will not be affected by the introduction of a safe water supply. Even with access to safe water, the community may continue to visit transmission sites for reasons including overcrowding or lack of privacy at the safe water source. Therefore, for the water infrastructure to be effective in preventing exposure to contaminated water bodies, it will require that risk awareness campaigns accompany the infrastructure implementation (see Objective 3 of WISER). While completely eliminating contact with infested water bodies may be unachievable, strategies should at least be targeted at reducing this contact during and after drug administration programmes, to minimise reinfection and hence maximise the value of the chemotherapy investment, thus hopefully allowing a move towards complete elimination of infection in the community.


1. Bergquist R, Kloos H, Adugna A. Schistosomiasis: Paleopathological perspectives and historical notes. In: Jamieson B, editor. Schistosoma: Biology, Pathology and Control: CRC Press; 2016.

2. Great Britain Army Medical Services. Memoranda on medical diseases in the tropical and sub-tropical war areas. London: 1919.

3. King CH, Bertsch D. Historical perspective: Snail control to prevent schistosomiasis. PLoS Negl Trop Dis. 2015;9(4):e0003657.

4. Sandbach FR. The history of schistosomiasis research and policy for its control. Med Hist. 1976;20(3):259-75.

5. Sturrock RF. Schistosomiasis epidemiology and control: how did we get here and where should we go? Mem Inst Oswaldo Cruz. 2001;96 17-27.

Developing new biotechnologies for detecting schistosomiasis parasites in water

Alexander Webb, Imperial College London, 02/11/2017

Access to a reliable source of clean water is a luxury many people and animals lack in the world. Parasites are a major water contaminant and are a concern in all parts of the globe. There is, therefore, an urgent need to research parasites and to discover new biotechnologies that can help us to detect and remove water-borne parasites so that we can improve access to safe drinking water for as many people as possible.

Parasites are living organisms that live in or on another organism (the parasite's host). Parasites thereby obtain easy access to nutrients from the host. One such family of parasites is the Schistosomes which cause a neglected tropical disease called Schistosomiasis. These parasites infect people via contact in infected freshwater courses. The widespread presence of this parasite gives rise to an estimated 280,000 deaths annually. In this WISER project, we are aiming to develop new technologies for detecting Schistosomes so that we can assess the efficacy of our new water treatment processes.  

The difficulty with dealing with this family of parasites lies in their life cycle. As part of its life cycle, Schistosomal eggs are released into watercourses via the urine or faeces of infected people/animals. The eggs hatch and release the Miracidial larvae, which then go on to infect the intermediate host - freshwater snails. These infected snails act as the reservoir for the larval stage (Cercarial larvae) that infects humans and other animals. The larvae infect humans and other animals via contact with their dermis (skin), which stimulates the release of proteases (protein-based enzymes that cut up other proteins) that enable the larvae to penetrate the host.

It is this part of the lifecycle that we are trying to detect. One of these released proteases, called elastase, is known to act upon the dermis and weaken it so that the larvae can enter the host’s body. We have therefore developed a range of bioreporters (also known as biosensors) that can detect and report (through colour change) the presence of this elastase enzyme – thus detecting schistosomes. Of course, we are continually aiming to improve our bioreporter designs to improve the specificity and/or sensitivity of detection. Since our bioreporter designs are modular, we can rapidly change and improve upon our existing bioreporter designs. For instance, we can change the output of the bioreporter such that a positive output, in that the presence of the parasite in the water has been confirmed, could result in a fluorescent signal or the enzymatic production of a coloured compound that is visible to the naked eye. The picture below describes how our published prototype bioreporters, which are localised on the surface of bacterial cells, work.


Detection of Schistosomes via the presence of the elastase activity. The bioreporters shown are whole-cell bioreporters in that they are part of the cell-surface of bacterial cells. Detection of elastase results in cutting of the bioreporter from the surface of the bacterial cell, and a ‘loss of colour’. Ref:    Webb  et al  (2016), Scientific Reports, 6:24725. DOI: 10.1038/srep24725   . Image used under licence CC BY 4.0.

Detection of Schistosomes via the presence of the elastase activity. The bioreporters shown are whole-cell bioreporters in that they are part of the cell-surface of bacterial cells. Detection of elastase results in cutting of the bioreporter from the surface of the bacterial cell, and a ‘loss of colour’. Ref: Webb et al (2016), Scientific Reports, 6:24725. DOI: 10.1038/srep24725. Image used under licence CC BY 4.0.

With the continued development of faster, more specific, and even more sensitive bioreporter designs, we hope that in conjunction with the rest of the WISER team, we will be able to develop new strategies to provide reliable sources of clean water free from parasite contamination.

Water, sanitation, and hygiene for the control of schistosomiasis

Jack Grimes, Imperial College London, 07/07/2017

Water, sanitation, and potentially hygiene are increasingly seen as key components of a sustainable schistosomiasis control strategy. Schistosomiasis control relies primarily upon distribution of praziquantel, the anthelmintic drug, which is highly effective at killing schistosomes. Praziquantel kills the adult worms, which live in the bloodstream. It thus prevents worm eggs subsequently being put into the blood, and causing inflammation, organ damage and other problems.

However, praziquantel does not prevent re-infection after treatment, and it is not effective against juvenile worms that might have infected a person in the weeks leading up to treatment. There is therefore increasing interest in complementing the praziquantel treatment with interventions to prevent transmission of the parasite. People become infected during dermal contact with water containing schistosome larvae (cercariae), and these cercariae are released by snails that were previously infected with other larvae (miracidia) that hatch from eggs in an infected person’s urine or faeces. There is therefore reason to believe that reducing contact with environmental water bodies (river, streams, lakes and so on, that might be infested with cercariae), and proper containment of excreta (urine and faeces) should reduce transmission of the disease. Furthermore, soap is toxic to cercariae, so its use during bathing and the washing of clothes in the river is thought to protect people from infection. However, there is surprisingly little evidence of the relationships between water, sanitation, and hygiene (WASH), and schistosomiasis. Starting to generate this evidence has been the focus of my PhD and postdoctoral work. This work has consisted of three main projects on schistosomiasis and WASH: a systematic review and meta-analysis, a descriptive review, and a national mapping project in Ethiopia.

If WASH is thought to reduce schistosome transmission, then an obvious place to start is to look at whether people with better access to WASH are less likely to be infected. In collaboration with colleagues at the Swiss TPH and Emory University, we carried out a systematic review and meta-analysis (open access paper) to bring together the data in the published literature, to answer that question. We found no studies on soap use and infection (perhaps because soap use, being an activity, is transient and more difficult to assess than access to water and sanitation infrastructure). However, we found that people with better access to safe water did have significantly lower odds of infection, as did those with better access to sanitation. This applied for all species of schistosome. Interestingly, the effect sizes (how much less likely infection was in people with better WASH) varied substantially from study to study – perhaps suggesting that there are many social and environmental factors that mediate an impact of WASH on infection. It’s well known that correlation does not imply causation, and these studies were all observational: their results (and those of the meta-analysis) must therefore be interpreted with caution. People with better WASH are less likely to be infected, but is this because of the WASH, or is it because they are of higher socio-economic status? Higher socioeconomic status likely confers better access to treatment, better knowledge of schistosome transmission and the seriousness of the disease, and perhaps less occupational exposure (people of higher socio-economic status might be teachers rather than fishermen, for example).

Even if water supplies provide safe water for drinking and cooking, schistosome transmission is likely to continue if other activities leading to contact with infested water are not provided for. Laundry and bathing, leading to frequent and long-duration contacts with infested water, are likely to be of prime importance. Here, Congolese refugees in Rwanda are making use of laundry slabs provided with safe water, thereby avoiding exposure to potentially infested water.  Image credit: Oxfam East Africa/Flickr .

Even if water supplies provide safe water for drinking and cooking, schistosome transmission is likely to continue if other activities leading to contact with infested water are not provided for. Laundry and bathing, leading to frequent and long-duration contacts with infested water, are likely to be of prime importance. Here, Congolese refugees in Rwanda are making use of laundry slabs provided with safe water, thereby avoiding exposure to potentially infested water. Image credit: Oxfam East Africa/Flickr.

With this in mind, the question of the impact of WASH on schistosomiasis can be approached from a different angle: what role does the biology of the parasites and their snail intermediate hosts suggest for WASH? With the same colleagues, we explored this question in a second, descriptive review (open access paper). This review highlighted some surprising aspects of the parasites’ biology. For example, while complete containment of eggs would cause a complete cessation of transmission, the result of containing 50%, 90%, or 99% of the eggs is unclear. It seems unlikely that these would result in 50%, 90% and 99% reductions in worms in people. Instead, it seems that very small numbers of eggs need to get into the water to maintain intense transmission: a miracidium infecting a snail can, over time, develop into tens of thousands of cercariae, each of which has the potential to develop into an adult worm in a person. Even if people have and always use adequate sanitation, infected animals, and eggs washing off the body or clothes might sustain transmission. While water contact has a more direct impact on infection levels, it is similarly difficult to predict the impact of various levels of reduction in water contact, on level of infection. A person coming into contact with infested water at twice the rate will not necessarily have twice the number of worms: immunology and physiology are important regulators of infection.

The third main project was the national mapping of schistosomes and soil-transmitted helminths in Ethiopia (open access paper), carried out in collaboration with the Ethiopian Public Health Institute, the Ethiopian Ministry of Health, the Schistosomiasis Control Initiative and the Partnership for Child Development. The primary aim of this project was to understand the burdens of these parasites across the country, in order to design a control programme. Happily, as children were tested for the parasites across the country, the school WASH was also assessed – allowing for a comparison between schools’ WASH and their parasitic burdens. Schools with more frequent water collection did indeed have higher Schistosoma burdens, but no significant difference was seen when comparing sanitation with schistosomiasis – lending support to the findings of the descriptive review. Once more, this work was observational: it generated evidence for the relationship between WASH and schistosomiasis, but again, it’s possible that correlation does not imply causation. This is the motivation for a hands-on testing of different water supply solutions, as will be seen in the WISER project.