Soil-Transmitted Helminthiasis (STH) Dossier Overview

Soil-transmitted helminthiasis (STH) refers to a group of intestinal parasitic infections caused mainly by Ascaris lumbricoides, Trichuris trichiura, and hookworms (Necator americanus and Ancylostoma duodenale). These infections are among the most common neglected tropical diseases globally and disproportionately affect populations living in conditions of poverty, inadequate sanitation, and limited access to clean water. School-age children are particularly vulnerable to the morbidity associated with STH, including anemia, malnutrition, impaired growth, and reduced cognitive development.

The World Health Organization has long recommended preventive chemotherapy as the principal public health strategy for STH control, complemented by improvements in water, sanitation, hygiene (WASH), health education, and strengthened surveillance systems, and provided guidance for Programme Managers in the Preventive chemotherapy in human helminthiasis (2006),   Helminth control in school-age children: A guide for managers of control programmes (2nd Edition, 2011). The WHO NTD Road Map 2021–2030 established ambitious targets for elimination of STH as a public health problem, with a strong emphasis on sustained reductions in moderate- and heavy-intensity infections among at-risk populations.

In 2017, WHO published: WHO Guideline: Preventive chemotherapy to control soil-transmitted helminth infections in at-risk population groups (2017), providing updated evidence base for STH control. These procedures support Member States in preparing national dossiers to request validation of elimination of STH as a public health problem.

Further, WHO has provided evaluation frameworks in:  Assessing the epidemiology of soil-transmitted helminths during a transmission assessment survey in the Global Programme for Elimination of Lymphatic Filariasis (2015), and more recently an clarified and updated Monitoring and Evaluation Framework for Schistosomiasis and Soil-Transmitted Helminthiasis (2024). 

The WHO criteria for elimination of STH as a public health problem include:

• Prevalence of moderate- and heavy-intensity STH infections below 2% among school-age children;
• Sustained achievement of this threshold under appropriate surveillance systems;
• Evidence of effective programme implementation, including preventive chemotherapy coverage of at least 75% of school-age children in endemic areas for a minimum of five years, where applicable; plus
• Evidence that the health system can sustain surveillance and respond to potential recrudescence. 

These standardized procedures are intended to guide Member States in preparing STH elimination dossiers for submission to WHO for validation of elimination milestones.

Current situation

In the WHO Regional Office for Africa African Region, substantial progress has been achieved in reducing the burden of STH through large-scale preventive chemotherapy programmes targeting school-age children and other at-risk populations. Several countries are approaching elimination thresholds for STH as a public health problem, while others are strengthening surveillance systems and integrated interventions to sustain gains.

The Region is also increasingly adopting integrated approaches linking STH interventions with school health, nutrition, WASH, maternal and child health, and broader neglected tropical disease programmes. New treatment combinations, improved diagnostics, and strengthened monitoring systems are further supporting progress toward the 2030 targets. As more countries near elimination thresholds, preparation and review of national STH dossiers are becoming an important regional priority.

Role of ESPEN

Expanded Special Project for Elimination of Neglected Tropical Diseases  (ESPEN) supports endemic countries in progressing toward validation of STH elimination milestones through:

• Provision of technical assistance for STH dossier development and finalization;
• Support for strengthening surveillance, monitoring, and evaluation systems aligned with WHO guidance;
• Review of draft dossiers and provision of informal technical feedback to countries;
• Convening Regional Dossier Review Groups for formal review of officially submitted dossiers;
• Supporting countries to address recommendations arising from dossier review processes;
• Facilitating regional coordination, technical capacity strengthening, and sharing of best practices for sustainable STH elimination. 

Contact Section:
ESPEN STH focal point: Dr Pauline Mwinzi – mwinzip@who.int