The World Health Organization (WHO) estimates more than 1.5 billion people are infected with soil-transmitted helminths (STHs) worldwide. That is:
The DeWorm3 approach
DeWorm3 tests the feasibility of interrupting the transmission of STH infections, to develop feasible, effective strategies for scaling-up transmission interruption programs.
One approach to interrupting the STH transmission cycle and prevent ongoing transmission to children is to broadly administer the deworming drug albendazole to people of all age groups in these areas (community-wide deworming) compared to the current regime of only deworming children (school-based deworming).
New modelling of STH transmission dynamics suggests that it may be possible to interrupt the transmission of STH using preventative chemotherapy (PC) alone – with an “intensified” community-wide MDA strategy.
The principal hypothesis:
- Three years of community-wide treatment with albendazole will be sufficient to interrupt transmission of each individual species in the same areas, whereas programmes targeted at pre-school and school-age children will not achieve such interruption.
DeWorm3 Endpoint Scenarios.© Arianna Means, DeWorm3
Current WHO guidelines
Current WHO STH guidelines recommend delivering preventative chemotherapy - albendazole or mebendazole - via
- mass drug administration (MDA) campaigns
- targeting pre-school and school-age children
- living in areas where the baseline prevalence of any STHs infection is 20% or higher among children.
The purpose of this strategy is to reduce STH-associated morbidity by reducing STH worm burdens in children.
However, the targeted approach is unlikely to break transmissions of STHs in the community because adults and other untreated community members may act as reservoirs for STHs infections, contributing to ongoing reinfection of treated children.
WHO 2030 NTD Roadmap
In 2021, the WHO launched it's high-level, strategic document and advocacy tool "Ending the neglect to attain the Sustainable Development Goals: a road map for neglected tropical diseases 2021–2030." The road map sets global targets and milestones to prevent, control, eliminate or eradicate 20 diseases and disease groups as well as cross-cutting targets aligned with the Sustainable Development Goals. Three foundational pillars will support global efforts to achieve the targets: accelerate programmatic action (pillar 1), intensify cross-cutting approaches (pillar 2) and change operating models and culture to facilitate country ownership (pillar 3). If DeWorm3 is successful, it could contribute towards the roadmap's global targets by reducing the amount of people requiring STH interventions, reducing the disability adjusted life years related to STH and contributing to the overall elimination of STH transmission.
- Focus: To identify effective drug-delivery strategies to interrupt soil-transmitted helminth transmission.
- Funding: Bill and Melinda Gates Foundation
- Start date: 2015
- End date: 2021
Anderson R, Truscott J, Hollingsworth TD (2014) The coverage and frequency of mass drug administration required to eliminate persistent transmission of soil-transmitted helminths Philos Trans R Soc Lond B Bio Sci 369: 20130435.
Preventive chemotherapy to control soil-transmitted helminth infections in at-risk population groups World Health Organisation, September 17 2017.