Progress towards schistosomiasis elimination in Cambodia and Lao PDR

“Transmitted by parasitic worm-infected snails living in contaminated water, the disease remains a significant public health concern in specific parts of both countries, adjacent to the Mekong River where the disease-transmitting snails can thrive,” said Dr Tim Armstrong, WHO Representative to Lao PDR.

“While sustained investment and commitment means that less than 1% of people living in high-risk locations are currently infected, the disease continues to affect thousands in Lao PDR, especially children, making relegating this disease to the past a health priority.”

In Cambodia, approximately 80 000 people are at risk of contracting schistosomiasis in 104 villages in two provinces, Kratie and Stung Treng, which are endemic for the disease.  

In Lao PDR the disease persists in southern Champasack Province, where an estimated 120 000 people reside in 202 high-risk villages across Khong and Mounlapamok districts. 

Left untreated, the disease can cause stomach pain, an enlarged liver, blood in stool, and even severe liver damage – with potentially fatal complications.  

“Schistosomiasis has been a persistent challenge in Cambodia for many years, silently affecting the most underserved populations,” said Dr Marianna Trias, WHO Representative to Cambodia.

“The disease spreads through everyday activities that bring people into contact with infested water from the Mekong River and its tributaries – such as washing, bathing, fishing, and collecting water – where poor hygiene and sanitation further heighten the risk among adolescents and adults. Thanks to the generous support from China and Switzerland, and through joint cross-border efforts, we are working to ensure that no one is left behind in our journey toward elimination.”

The funding – US$1.41m via the Global Development and South-South Cooperation Fund (GDF) of China, and US$1.09m via Switzerland – is enabling a range of comprehensive efforts between June 2024 – May 2026 aiming to ensure zero cases of new locally-transmitted schistosomiasis infections in snails, animals, and humans, with full elimination by 2030.

Key activities include: mass drug administration to clear infections in children and adults in all endemic villages, with more than 175 000 people anticipated to receive treatment; communications for health to raise awareness of risks and prevention; enhanced disease surveillance and building testing capacity; and improved access to clean water and sanitation facilities in villages to reduce transmission.

In support of this, technical assistance is being provided by China’s National Institute of Parasitic Diseases and the Swiss Tropical and Public Health Institute, via training and capacity building for Lao and Cambodian Ministries of Health staff and provincial officials.

WHO has also worked to ensure national health systems are being strengthened in the long-term via the project’s interventions.

This aims to ensure sustainability, particularly building capacity for public health officials at the national, provincial and district level on disease surveillance, and establishing a centralized surveillance data system, allowing schistosomiasis to be more accurately tracked as elimination nears.  

Manivanh Khammanolard, Deputy Head of the Khong District Health Office, has seen first-hand the impacts of schistosomiasis, and is proud to contribute to its elimination.

Regularly implementing elimination activities supported by China and Switzerland, Manivanh supports health promotion – particularly regarding causes of infection, and prevention through good hygiene and sanitation – as well as monitoring of cases, investigations of suspected cases, and mass-treatment efforts.

She says: “It is difficult for people to avoid risky behaviours, because they rely on the river for daily life, including food and income – while some are aware of the disease, but do not take action, or are unaware how dangerous schistosomiasis can be.”

“If schistosomiasis can be eliminated, the community will have better health, more children will be able to go to school, and people will have greater opportunities to work and improve their lives. Fortunately, through education, distribution of medicine, and improved access to clean water, sanitation and toilets especially, we can make progress.”

Given its spread via infested water, improving hygiene and sanitation is a major focus for the project. In 36 villages (directly supporting 34 937 people) across both countries, community-led initiatives to eliminate schistosomiasis by combining deworming with WASH interventions (CL-SWASH) are underway.

As part of this approach, elected committee members conduct household visits to assess latrine use, sanitation practices, and water supply. In many cases, this has resulted in steady improvements in sanitation coverage, primarily making use of the community’s own resources.

Complementing these efforts, support is ensuring access to clean water and improved hygiene is more widely available in high-risk schools and communities.

“While mass drug administration treats infections, sustainable schistosomiasis elimination relies heavily on robust WASH,” said Dr Huy Rekol, Director of the National Center for Parasitology, Entomology and Malaria Control (CNM) in Cambodia. “Providing safe water, improving sanitation, and promoting good hygiene directly disrupt the parasite’s life cycle. WASH is the long-term solution that empowers communities to break the cycle of infection.”

Alongside improved sanitation, educating community members, particularly children, is crucial to keeping people safe – and has been a key focus.

Bounlaiy Sackpasith (pictured below), father of two and Principal of Thakham Primary School, knows how essential awareness is to keeping children and communities safe.

“As a teacher, an important role I play is integrating schistosomiasis lessons into our teaching curriculum,” he says. “Most students now have a better understanding of how dangerous the disease is, and how to prevent it, particularly with good hygiene. It’s important to introduce this topic at the primary school level, because children pay more attention and learn the importance of using toilets.”

Bounlaiy continues: “At our school, to help prevent the disease, support has seen handwashing sinks built, and promotion to encourage the children to wash their hands. After including information about the disease in lessons, and using the toilet correctly.”

Combined, support will see more than 50 000 students reached across hundreds of schools in high-risk areas.

“Eliminating schistosomiasis in the Mekong region is within reach — now more than ever, success relies on collective effort. We are witnessing this collaboration in action through treatment, surveillance, education, and WASH. Together, we can achieve it — that’s the spirit of our partnership among Laos, Cambodia, China, Switzerland, and WHO. From individuals and communities to national institutions, renowned research institutes, and global organization, we are uniting to turn the impossible into reality and drive progress toward eliminating this disease once and for all,” said Jean-Gabriel Duss, Regional Director, Swiss Agency for Development and Cooperation in Mekong Region.

Finally, the most visible and crucial aspect of elimination efforts is mass administration of medication – also known as mass-drug administration. To date, more than 138 000 people have been provided a single-dose of praziquantel – which fully eliminates schistosomiasis from the body – across 103 villages.

Across the entire project, more than 280 000 people will be treated to eliminate schistosomiasis infection.

“This essential step ensures communities are infection-free, and combined with all other efforts, helps break the cycle of reinfection, and moves us closer to a schistosomiasis-free Lao PDR and Cambodia,” said Dr Virasack Banouvong, Director of Center for Malaria Parasitology and Entomology in Lao PDR.

“Achieving elimination of schistosomiasis mekongi will require strong political will, multisectoral and regional collaboration, community engagement, national technical expertise, integrated interventions, and robust systems for surveillance, monitoring, and evaluation. It’s a lot – but – we know it can be done, and must be done, to protect people’s health and way of life.”