Back to WATER INSIGHTS
By Tyne Eckmyn, Publishing Associate: Researcher and Writer at Save the Water™ | February 11, 2026
Edited by Joshua Awolaye, Publishing Associate: Editor at Save the Water™
Globally, hundreds of millions of people rely on water sources that are home to a parasitic worm called Schistosoma. This worm causes a disease called schistosomiasis. It affects roughly 240 million people globally, making it the second most significant parasitic disease after malaria. Schistosomiasis is most prevalent in tropical and sub-tropical regions like northern South America, Sub-Saharan Africa, and parts of Southeast Asia. Poorer communities lacking public health, sanitation, and water infrastructure are the most affected.
Schistosoma worms live in freshwater bodies such as rivers and lakes. They enter the human body by burrowing in through the skin during contact with polluted water. Once inside, the parasites migrate through the bloodstream, infect organs, and reproduce by laying eggs. These eggs are then released through the stool of infected individuals. In communities with poor sanitation systems, it can enter nearby rivers and lakes.
Once back in the water, the eggs hatch and infect certain species of freshwater snails, which serve as temporary hosts. Within the snails, the parasites grow and reenter the water as free-swimming larvae. At that point, they are able to infect humans.
Symptoms of infection can vary. In the first few months, they may include fever, diarrhea, muscle cramps, blood in the stool, and organ damage. Repeated infections can lead to anemia, malnutrition, and learning difficulties. The disease’s burden is particularly high among children, who are more likely to swim or play in unsafe water. Also, chronic infection can stunt both their mental and physical development if untreated. Although schistosomiasis mainly causes disability, the World Health Organization estimates it still causes about 12,000 deaths worldwide each year.
Cambodia and Lao PDR efforts focus mainly on communities along the Mekong River, where the schistosome species Schistosoma mekongi is endemic. Their approach to eliminating the disease has four parts: treatment, surveillance, education, and infrastructure.
Treatment: Mass drug administration campaigns using praziquantel aim to eliminate the parasite from entire populations in high-risk areas. Treating infected individuals at scale reduces transmission from humans back into local water sources.
Surveillance: Improved monitoring of new infections and potential outbreaks allows public health authorities to respond quickly. This ensures timely treatment and limits further spread of the disease.
Education: Programs that work with local communities and youth organizations focus on increasing awareness of transmission risks. They promote practical steps that individuals can take in their daily lives to reduce exposure.
Infrastructure: Improvements in water, sanitation and hygiene (WASH) infrastructure aim to improve the safety and cleanliness of water sources. They also keep sewage and wastewater from contaminating water bodies.
In addition to this four-part strategy, health authorities in Cambodia and Lao PDR are coordinating cross-border efforts. These will reduce transmission of the parasite along shared waterways and prevent resurgences wherever the disease is eliminated. In Lao PDR, where schistosomiasis still affects about 120,000 people in the Mekong region, the goal is elimination by 2035. Cambodia, where an estimated 80,000 people remain at risk, should get rid of it by 2030.
Lack of access to clean and safe water is, of course, a challenge not limited to Southeast Asia. Poor and rural communities worldwide face the same problem. The work done by Cambodia, Lao PDR, and their international partners already offer valuable lessons. It will also provide a model for other regions seeking to eliminate water-related diseases across borders in the coming years.
Save the Water™ is a 501 (c)(3) non-profit organization with a mission to conduct research to identify and remove harmful contaminants in water and to raise public awareness about water contamination and its health impacts.
