7 challenges and opportunities to eliminate soil-transmitted helminth infections

07 May 2019
 Progress for PC coverage (by country) in SAC and where STH infection is no longer considered a public health problem (MHI <1%).

Every year the Soil-Transmitted Helminthiasis (STH) Advisory Committee brings together leading experts to discuss and identify the best practices and opportunities for the prevention and control of the parasitic worms.

With the end of the WHO 2020 roadmap on NTDs in sight, this meeting provides a vital resource to revitalise and shape the control and elimination policies and strategies that will be implemented in the coming years.

In November 2017, discussions centred on the critical need to develop a data-driven guide to the STH endgame on late-stage programme functioning, processes, and surveillance. The focus was on research and field experiences from countries approaching the “elimination of STH infection as a public health problem”.

From this meeting the Committee (including LSHTM's Dr Rachel Pullan) published a special PLOS NTDs article that identified seven key areas that need attention and proposed recommendations for immediate action.

Challenges and recommendations

Challenge #1: Incomplete and inconsistent monitoring of programme impact
Define standard impact goals and targets post-2020.

In line with WHO recommendations, current reporting is often focused on treatment coverage rather than on the impact of that treatment. The impact data that is available, often varies from place to place thereby limiting comparison and analysis.

Country programmes require a comprehensive, standardized, yet flexible approach to measure progress toward morbidity-related goals. Such an approach would capture essential programmatic elements and can be used by countries to map their needs, commitments, and resources.

The WHO’s ESPEN programme, has successfully collected data on 5 preventive chemotherapy (PC) NTDs from 47 African countries in Africa. This approach should be rolled out in other regions where STHs are endemic.

Challenge #2: Reaching at-risk groups other than school aged children 
Identify new PC strategies, platforms, and reporting mechanisms.

Analysis shows that control programmes that include the wider community rather than just focusing on school-aged children are more effective. Currently, many national control programmes are school-based.

There is a need for the WHO to develop implementation guidelines to help countries target at risk groups including women of reproductive age and pre-school-aged children.  Operational research is needed to define platforms, partners, and reporting tools to monitor progress of control programmes that target all at risk groups.

Attention also needs to be paid to the development and supply of safe and effective drugs suitable for these groups.

Challenge #3: The risk of anthelmintic drug resistance
Recommendation: Develop standardized indicators to detect emerging resistance.

As vets well know, years of large-scale treatment with the same drugs can result in anthelmintic drug resistance. In terms of human treatment, there are currently no routine, field-applicable diagnostics that can effectively identify and monitor signs of emerging resistance.

A standardized approach to the monitoring of potential emerging resistance needs to be established to track both drug efficacy and mutations known to be associated with resistance.

Challenge #4: Poor diagnostics to assess programme needs by implementation stage
Employ validated programme stage-specific diagnostic techniques.

The Kato–Katz technique, while relatively inexpensive, widely used, and sensitive is less effective in low-prevalence settings. There is a need for new, highly sensitive tests that can be employed in settings that are moving from STH control to elimination.

Challenge #5: Limited efficacy of current drugs and gaps in drug availability
Promote research into combination therapies and fast track pre-qualification processes.

The existing anthelmintic drugs have variable efficacies against different STH species, with particularly low efficacies against T. trichiura when using single-dose treatments. New efforts must be undertaken to provide guidelines for use cases for combination therapies in general and specifically in which T. trichiura is the predominant species. Additionally manufacturers will need to become prequalified to meet the growing demand from STH control programmes.

Challenge #6: Limited coordination with the water, sanitation, and hygiene (WASH) sector
Identify WASH indicator(s) to be included in routine STH M&E.

The 2020 WHO Roadmap identified the critical role of WASH in the control of STH infection but did not set actionable targets or strategies. Building on the WHO WASH–NTD global strategy there is a need for improved quantification of the specific mechanisms and use of consistent indicators to identify and remedy potential WASH short-comings.

Challenge #7: New targets needed for post-2020
Develop clearly defined, quantitative programme targets for all at-risk groups and move beyond PC coverage estimates.

There is a need to look beyond simple coverage measures and include impact targets for other at-risk groups such as women of reproductive age and pre-school-aged children. Benchmarks for WASH will encourage investment in WASH in STH-endemic areas. Estimates of PC uptake along the distribution chain that would give accurate estimates for not only availability of the drug, but population compliance.


The experts concluded that whilst there has been significant success work remains to accelerate action to achieve the elimination targets in many places. Progress that builds on the 2020 Roadmap will be achieved through active collaboration and coordination by government ministries, researchers, donors, WHO, drug manufacturers, and multisectoral collaboration.

Download the publication

Freeman MC, Akogun O, Belizario V Jr, et al. (2019) Challenges and opportunities for control and elimination of soil-transmitted helminth infection beyond 2020. PLoS Negl Trop Dis 13(4): e0007201.