By Professor Russ Stothard
Schistosomiasis remains one of the most persistent and insidious neglected tropical diseases (NTDs), quietly afflicting tens of millions of people worldwide. Despite being a recognised public health priority, the disease remains overlooked, underdiagnosed, and undertreated.
The push towards schistosomiasis elimination by 2030, spearheaded by the World Health Organization (WHO), is an ambitious but necessary goal. After two decades of research on this disease, I know there are still significant challenges in diagnosis, treatment, and control strategies, threatening to undermine progress.
Diagnostic dilemma
For any disease, accurate diagnosis is the cornerstone of effective treatment and control. Yet, for schistosomiasis, existing diagnostic tools are far from perfect.
Diagnosis is done by examining stool samples or filtering urine and then counting the number of Schistosoma parasite eggs under a microscope. While inexpensive and widely used, these methods suffer from low sensitivity, particularly for light infections. The number of eggs people excrete at any given time can also vary significantly, and missing an infection due to a single negative test is not uncommon.
More advanced molecular tests, such as PCR tests and loop-mediated isothermal amplification (LAMP) methods, offer higher accuracy but remain inaccessible in many endemic regions due to cost, the need for specialised equipment and fragile consumable supply chains, and the complexity of sample preparation.
Meanwhile, rapid diagnostic tools like the circulating cathodic antigen (CCA) test have gained traction. Still, their inconsistent performance across different Schistosoma species and different people, such as children and pregnant individuals, limits their utility as a standalone tool.
Without accessible, highly sensitive, and species-specific diagnostic tools, the burden of schistosomiasis will continue to be underestimated, delaying much-needed treatment and intervention efforts.
Challenges of treatment and control
Praziquantel has been the backbone of schistosomiasis treatment for decades. As the only widely available drug, its mass drug administration (MDA) programs have successfully reduced morbidity in many endemic regions.
However, MDA alone is not a silver bullet. Reinfection rates remain high, and the long-term sustainability of repeated praziquantel use is questionable. While not yet fully confirmed, reports of reduced efficacy and the potential for resistance underscore the urgent need for alternative treatments or combination therapies.
Another growing concern is hybrid schistosomes, parasites resulting from interspecies hybridisation between S. haematobium, the schistosome parasite found in humans, and livestock-related species. These hybrids are not only more challenging to detect using standard diagnostics but also raise serious questions about praziquantel’s long-term efficacy.
WHO has recognised the need to extend schistosomiasis treatment to animals, embracing a One Health approach to tackle transmission across human and animal reservoirs. Implementing this strategy remains a daunting challenge, particularly in regions with limited veterinary healthcare infrastructure.
Migrant health and schistosomiasis on the move
A notable aspect of the disease is that many people are infected asymptomatically for long periods without being aware of the parasites living within them. This has resulted in cases of schistosomiasis cropping up in Europe and beyond with a major outbreak in Corsica in 2013.
If schistosomes spread to Europe it would serve as both a public health risk and a potential distraction from elimination efforts in Africa. This means that attention must be paid to the improving the health of those entering Europe, particularly migrants from sub-Saharan Africa, with presently poorly managed schistosomiasis.
Indeed, expanding access to appropriate medical screening services within a point-of-exit and point-or-entry would make migration safer, prevent the spread of other diseases and be a significant step towards improving universal health coverage.
Looking ahead: Innovation and integration
Although the road to schistosomiasis elimination is fraught with challenges, those that have travelled this route still know there are reasons for optimism. Technological advancements, such as artificial intelligence-assisted microscopy, are enhancing diagnostic accuracy and efficiency.
At the same time, novel drug candidates and vaccine research are progressing. A paediatric formulation of levopraziquantel is set to improve treatment accessibility for preschool-age children, with first steps in deployment taken in Uganda taken earlier this year. Several vaccine candidates are moving through clinical trials, offering hope for adjunct long-term control strategies.
No single intervention will be sufficient on its own. Achieving WHO’s 2030 targets will require a more integrated approach that combines improved diagnostics, better access to treatment, snail control strategies, water and sanitation improvements, and community education. Efforts to enhance surveillance, precision mapping, and monitoring drug efficacy must be prioritised to ensure that control programmes remain effective in the face of evolving challenges.
A Call to Action
Schistosomiasis elimination is not an unattainable dream. The tools, expertise, and knowledge exist, but progress will stall without greater investment, coordination, and innovation. Governments, researchers and funding bodies must recognise that while the disease may be ‘neglected’ in name, it cannot afford to be neglected in action. Achieving meaningful progress will require a shift from short-term interventions to long-term sustainability, ensuring that future generations are free from the burden of this devastating disease.
This opinion piece is based on Professor Stothard’s landmark seminar paper in The Lancet. Read it in full here: https://lstm.ac/LancetHumanSchistosomiasis