Zanzibar makes substantial progress towards elimination of schistosomiasis

Unlimit Health now aims not only to treat parasitic disease, but to eliminate it altogether, in line with the World Health Organization (WHO) road map for neglected tropical diseases 2021–2030.

Evidence suggests that the existing strategies of deworming treatment, targeting school-age children, are not sufficient to achieve elimination of parasitic disease.

This is why, in addition to expanding our support for treatment to include further at-risk groups, we work on addressing the key drivers of parasitic disease, such as unsafe water contact and transmission between animals and humans. 

Impact assessments to reach elimination

To further our efforts towards elimination, we are working with several ministries of health (MoH) to conduct impact assessments. Impact assessments seek to measure progress following treatment cycles, measure the current prevalence of schistosomiasis and soil-transmitted helminths, and improve knowledge on disease distribution. By conducting impact assessments, treatment strategies can be adapted to reflect new findings, progress towards elimination can be accelerated by focusing on high-prevalence areas and hotspots, and the risk of over- and/or undertreatment can be minimised through improved data and drug allocation.

A Zanzibar case study 

In collaboration with Zanzibar’s MoH, we supported the collection of data by sampling communities through community-based sampling from July to August 2024.

After cleaning and collecting the data, we used a geostatistical methodology to generate an improved epidemiological understanding of schistosomiasis (SCH) and soil-transmitted helminths (STH) across Unguja, Pemba and other archipelago islands of Zanzibar.

For SCH, prevalence was presented at the sub-district level, known as a ‘shehia’, which is a small local administrative area of the country, while for STH, the focus was on the larger district-level prevalence. 

Learn about geostatistical mapping

 The results for SCH were promising: a mere 7% of shehia were classified as having a prevalence of >10% based on the impact data, as compared with 2023 classifications which indicated 81% for the same category.  

However, the situation for STH remains challenging, with district-level prevalence rates predominantly still above 20%, indicating the need for further investigation and intervention.

In January 2025, we joined the Ministry of Health (MoH) and local stakeholders in for the national impact assessment meeting where the data and findings were discussed. 

During the meetings, discussions covered key topics such as elimination planning for schistosomiasis, particularly in low-prevalence areas, but also planning how to address the high prevalence of STH.

Action points were developed including exploring how different authorities within the country (such as those responsible for water, agriculture, livestock) could potentially collaborate on projects which aided elimination, as well conducting further research into how diseases were being transmitted, and the factors influencing how prevalent SCH and STH are.  

This meeting marked a significant step in advancing Zanzibar’s efforts to eliminate parasitic diseases, and we look forward to continuing our partnership with the Ministry of Health in tackling parasitic diseases.  

We will continue working with our ministry of health partners in many countries to conduct impact assessments, ensuring programmes are better informed and more effective in reaching those most in need.