Toward the 2020 goal of soil-transmitted helminthiasis control and elimination

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On May 22, 2001, a resolution passed during the 54th World Health Assembly (WHA 54.19) took an historic step toward reducing the morbidity and mortality associated with the world’s most common parasitic worm (helminth) infections [1]. Indeed, an estimated 1.45 billion individuals are infected with soil-transmitted helminths worldwide [2]. The soil-transmitted helminths primarily comprise hookworm (Ancylostoma duodenale and Necator americanus), roundworm (Ascaris lumbricoides), and whipworm (Trichuris trichiura). Taken together, soil-transmitted helminthiasis accounts for a global burden of over 3.3 million disability-adjusted life years [3] and is associated with anemia [4], malnutrition [5], and impaired physical and cognitive development [69]. As the primary recommendation to eliminate soil-transmitted helminthiasis as a public health problem, WHA 54.19 called for improved water and sanitation to reduce transmission and urged that 3 high-risk groups receive regular treatment with anthelmintic drugs: preschool-aged children (PSAC), school-aged children (SAC), and women of reproductive age (WRA) [1].

During the decade 2001–2010, however, soil-transmitted helminthiasis control focused almost exclusively on preventive chemotherapy targeting SAC through the education sector, with a target of achieving at least 75% drug coverage in this population group by 2010 (Table 1). While this target was not reached [10], global efforts to address soil-transmitted helminthiasis were renewed in 2011, when several high-level meetings took place and their reports published in subsequent years. The “Roadmap on Neglected Tropical Diseases” was published first, reiterating the 75% preventive chemotherapy coverage target for PSAC and SAC [11]. This roadmap inspired 22 partners from public and private sectors to endorse the London Declaration on Neglected Tropical Diseases [12] and called on all partners to sustain and expand programs to achieve the 2020 goals outlined in the roadmap. Subsequently, a specific strategic plan for soil-transmitted helminthiasis was published, also in 2012, in which, on top of the 75% target for coverage, the additional target of reducing moderate- and heavy-intensity infections (defined as the number of helminth eggs excreted by an individual exceeding a preset, species-specific threshold, used as a proxy for worm burden) to less than 1% among SAC was affirmed [13]. With 2020 on the horizon, we are well into the second decade post-WHA 54.19. Major challenges remain. Among others, these include (1) the need to maximize the impact of pharmaceutic donations of anthelmintic drugs, (2) the need to clarify targets to guide monitoring efforts moving forward, and (3) the need to take into account recent successes of the Global Program to Eliminate Lymphatic Filariasis (GPELF). The latter challenge results in the consequent scaling down of community-based control interventions, thus reducing the ancillary benefits of this strategy on soil-transmitted helminthiasis [14]. A complete transition from a lymphatic filariasis elimination program to a soil-transmitted helminthiasis control program will have important consequences so that efforts to ensure that all risk groups for soil-transmitted helminthiasis will be adequately covered need to be planned well in advance of the actual transition.

If the goal of eliminating soil-transmitted helminthiasis as a public health problem is to be achieved, it is important to proactively review and address gaps in disease control programs. The Soil-Transmitted Helminthiasis Advisory Committee (subsequently termed “the Committee,” established in 2012, as the successor of the Mebendazole Advisory Committee that was launched in 2006) is an independent group of experts that holds an annual meeting to assess challenges and review progress made in soil-transmitted helminthiasis control, including operational research, monitoring, and evaluation, and to deliberate on next steps. The Committee makes recommendations to address technical and scientific challenges and provides advice to members of the Soil-Transmitted Helminthiasis Coalition and the World Health Organization (WHO) Strategic and Technical Advisory Group (STAG). On October 18–19, 2016, the Committee convened for 2 days in Basel, Switzerland, to review and discuss advances in operational research, anthelmintic treatment options, and diagnostic tools and strategies. Furthermore, programmatic and strategic challenges in global control efforts were debated. Here, we present the recommendations arising from this meeting and highlight challenges and potential solutions on the road toward the 2020 goal of soil-transmitted helminthiasis control and elimination and beyond.