Cambodia moves closer to eliminating schistosomiasis mekongi

On World Neglected Tropical Diseases Day 2026, we look at Cambodia’s major progress towards eliminating schistosomiasis mekongi, a parasitic disease that once posed a serious public health threat along the Mekong River. Through decades of sustained mass drug administration, strengthened surveillance, improved sanitation and strong community engagement, the country has reduced disease prevalence to very low levels, bringing Cambodia within reach of elimination and demonstrating what long-term commitment to neglected diseases can achieve.

Found only in two countries in Southeast Asia—Cambodia and the Lao People’s Democratic Republic—schistosomiasis mekongi may sound unfamiliar today. Yet for decades, its impact was deeply felt by communities living along the Mekong River.

“Twenty years ago, schistosomiasis was very common at my hospital, and many cases were severe,” recalled Mr Phan Tola, Director of Sambour Referral Hospital in Kratie Province. “We saw two to five cases each day, with symptoms such as blood in stool, enlarged liver and spleen, and abdominal swelling.”

Now, that reality seems far away.

Disease prevalence has fallen from over 70% to less than 1% across all sentinel sites, largely due to the sustained implementation of regular mass drug administration (MDA). By 2016, schistosomiasis mekongi was no longer considered a public health concern in Cambodia, although continued surveillance remains essential to prevent re-emergence.

"I haven't seen any cases," said Mr Tola. "This has eased the hospital's workload, with fewer severe admissions."

Breaking the disease cycle

As its name suggests, schistosomiasis mekongi primarily affects communities living along the Mekong River and its tributaries. Kratie and Stung Treng are Cambodia’s highest-risk provinces.

Transmission occurs when parasitic larvae released from freshwater snails penetrate human skin. A critical part of the transmission cycle is open defecation, where water carries parasite eggs back into the river, allowing the disease to continue spreading.

Since 1996, the Ministry of Health has implemented regular MDA to interrupt transmission, reaching large numbers of people across affected communities. Over time, this was complemented by an integrated approach that combined treatment with health education and improved sanitation, key measures to prevent resurgence.

Village health volunteers and teachers play a key role in translating this vision into daily practice.

Community engagement at the heart of success

“Before, we had only eight toilets in the entire village,” said Ms Ouk Em, a member of the Village Health Support Group (VHSG) in Kampong Krabei village, Kratie province.

Every day, Em visits households to promote hygiene practices and encourage latrine use.

Ms Ouk Em, a Village Health Support Group (VHSG) volunteer, visits a villager who previously underwent surgery due to schistosomiasis. © WHO / Monika Mey

“At first, people didn’t want to build latrines. They said it was useless and a waste of money,” she explained. “But once we explained how schistosomiasis spreads, they became afraid and began to understand the importance of protecting themselves.”

After 20 years as a health volunteer, Em has witnessed a remarkable transformation. Her village now has more than 100 toilets and has been declared Open Defecation Free, a critical milestone in breaking the transmission cycle.

Schools have also played a central role in reinforcing healthy behaviors from an early age.

At Kampong Krabei Primary School, Ms Mao Sreynich (right) and her colleague regularly remind students about the risks and prevention of schistosomiasis. © WHO / Monika Mey

“At my school, teachers regularly remind students to wash their hands, usually before lessons or breaks,” said Ms Mao Sreynich, a teacher at Kampong Krabei Primary School. “We also display posters in classrooms to reinforce habits like washing hands and using a toilet. It’s important to tell the children to practice these habits at home as well.”

“I’ve noticed improvements in most students, especially in handwashing. When the bell rings, I see students run to wash their hands before buying snacks. It makes me happy to see them practicing good hygiene,” added Sreynich.

International collaboration and surveillance

Sustaining progress toward elimination requires strong partnerships and continuous surveillance. The World Health Organization (WHO) has been a key technical partner to the Center for Parasitology, Entomology, and Malaria Control (CNM) of the Ministry of Health, supporting Cambodia’s efforts to eliminate schistosomiasis mekongi.

This support has been made possible with generous financial contributions from the Global Development and South-South Cooperation Fund of China and the Swiss Agency for Development and Cooperation.

During a Kato-Katz demonstration, health workers in Kratie and Stung Treng learned stool examination techniques to track schistosomiasis eggs and monitor disease prevalence. © WHO / Monika Mey

Through this collaboration, the National Institute of Parasitic Diseases and the Swiss Tropical and Public Health Institute are partnering with Cambodia to strengthen local capacity in surveillance, including stool examination techniques such as Kato-Katz, to detect schistosomiasis eggs and monitor potential hotspots.

This technical cooperation is essential for early detection and rapid treatment response. By identifying and treating individual cases or conducting targeted MDA in hotspots, Cambodia can effectively interrupt any remaining transmission and ensure that gains toward elimination are sustained.

The way forward

Cambodia’s progress against schistosomiasis mekongi demonstrates what is possible through long-term commitment, strong partnerships, and community leadership.

Working alongside the Ministry of Health, health workers, and communities, WHO will continue to support Cambodia in maintaining surveillance, strengthening prevention, and safeguarding hard-won gains—so that a future free from schistosomiasis is firmly within reach.

This elimination effort stands as a powerful reminder that no one is left behind, even in the fight against the most neglected diseases.