Policy action 1: Target deworming drugs to the right people, in the right place, in the right quantity

“Equity’s role is to prevent the law from adhering too rigidly to its own rules and principles when those rules and principles produce injustice”—Aristotle

With the first large donation of anthelmintic drugs for STH and morbidity control as the primary objective, health and education ministries sought to scale up access as quickly as possible, for as little cost as possible. The strategy adopted in many settings was school-based deworming administered by teachers, with the frequency of deworming determined by a baseline threshold. District-level prevalence was often established from aggregated available national data and erred toward increased access since donated high-quality drugs were extremely safe and offered in a one-tablet single oral dose. Deworming campaigns have also been integrated with other neglected tropical disease (NTD) control programs and delivered to whole communities, but stand-alone administration is usually school based. The epidemiologic profile of endemic countries is likely to have changed considerably since programs were initiated, and there is an urgent need for surveys with sufficient precision to target those still at risk. To improve targeting of deworming drugs based on empirical data and epidemiological evidence, this may mean moving away from district-level implementation units to smaller ones that better delineate areas of ongoing transmission and targeting high-risk populations within geographies. This would require a more considered sampling approach tailored to the setting and decisions to be made.

With an anticipated reduction in prevalence and intensity of infection as the programs reach high population and geographic coverage, WHO guidelines call for impact surveys after ≥5 years of regular deworming [10]. As of 2019, only 15/102 (approximately 15%) of endemic countries have been able to collect these crucial monitoring data [11]. As a result, drug requests based on population rather than current epidemiology continue without being contingent on evidence of morbidity. Where programs have conducted parasitologic surveys, STH prevalence and intensity have been dramatically reduced, and the morbidity target met [2,9,12]. Conversely, where control programs have failed to reach adequate geographic and population coverage, there are likely hot spots with high parasite burdens and risk of morbidity. Continuing with the status quo of population-driven, rather than prevalence and morbidity-driven, programming fails to adequately account for impact of the program and increasingly different epidemiologic situations of prevalence and intensity following years of deworming.

Population-based programming may also exacerbate the challenges associated with the limited resources available for STH control programs. Despite being cost-effective [13], deworming programs place significant demands on governments and communities regarding time, energy, attention, and resources. An epidemiologic-informed approach will help allocate scarce resources toward individuals who still require treatment and away from those who are no longer at risk. While funding for monitoring STH control programs is typically limited, investing in field-based epidemiologic surveys is crucial after ≥5 years of successful deworming to target treatment. Since the risk of intestinal worms is environmentally linked, geostatistical modeling approaches can be used to guide programs toward high-risk areas and to make decisions on treatment frequency [14]. Where the WHO NTD Road Map target has not been reached, and people are still at risk of parasite-related morbidity, STH control programs must move beyond the school and embrace context-specific innovative delivery platforms and a comprehensive strategy that leaves no one behind. These may include integration with other mass drug administration programs, antenatal clinics, immunization programs, or other population-based public health programs.

Policy action 2: Use the right drug(s) for the prevalent parasite species

Despite over a decade of deworming efforts, certain geographic areas still have MHI infection prevalence among children that surpasses the WHO-specified threshold of 2% [15]. This can, in part, be attributed to high baseline prevalence and programmatic issues such as low treatment or geographic coverage; however, the choice of therapeutic regimen might also contribute to the persistence of these infections [16].

Large-scale deworming programs are typically based on albendazole (400 mg) or mebendazole (500 mg) monotherapy. This is not because these regimens are the most efficacious or the best choice in clinical practice but because they are safe and easy to administer (a standardized single oral dose) and are suited to scale up in large populations because of the donation programs. While monotherapy albendazole and mebendazole are highly efficacious against A. lumbricoides (egg reduction rate (ERR): >95%), they are considerably less efficacious against T. trichiura (ERR: >50%). Similarly, the drugs are efficacious but suboptimal for hookworm (albendazole ERR: >90%, mebendazole ERR: >70%) [16]. The scientific evidence that there are more effective therapeutic regimens using single or combination therapy is compelling. However, shifting programs away from less-efficacious but free drugs to the most efficacious drugs requires a paradigm shift in thinking [17,18]. An exception is the combination therapy of albendazole plus ivermectin, which has already been safely distributed in areas where STH was co-endemic with LF. This combination was recently added to the WHO Model Lists of Essential Medicines for treating STH [19].

In addition to the superior therapeutic efficacy for T. trichiura and hookworm [17], and the long-term programmatic impact on T. trichiura infections [20], this combination therapy has several advantages over monotherapy. Firstly, it has intrinsic efficacy in controlling S. stercoralis, and hence, upscaling this combination therapy for STH control contributes to WHO targets 1 and 4 (Table 1). Secondly, it has been shown in veterinary medicine that combination therapy slows the emergence of anthelmintic resistance [21]. Thirdly, ivermectin can reduce other NTDs, including scabies, ectoparasites, and mosquito-borne diseases [22]. The administration of albendazole plus ivermectin combination therapy is more challenging than monotherapy as the ivermectin dose can be more than one tablet, based on height. Research is being conducted to evaluate a single fixed dose albendazole/ivermectin co-formulated tablet [23].

Targeting the right parasite species with the right drug(s) is crucial for optimally treating STH and achieving 2030 milestones. Novel treatments are currently being developed, with emodepside being the front-runner [17]. Yet, we do not have to wait for these compounds to reach the market: in intervention areas where morbidity from any species is low or where A. lumbricoides is the dominant species, monotherapy with either albendazole or mebendazole is an optimal use of resources; where hookworm is prevalent, albendazole should be used; and where T. trichiura is the predominant species, programs should use albendazole plus ivermectin. The time is now to reset the strategy to sustainably focus on offering the remaining affected people deworming drugs that are locally effective against the parasites causing morbidity.

Policy action 3: Increase coordination, accountability, and country ownership

WHO has provided guidance for national deworming programs, while pharmaceutical companies and other agencies have donated billions of deworming tablets, and national programs and their partners have mobilized to distribute them, all greatly reducing morbidity attributable to intestinal worms [24]. The strategy has been based on assumptions: universally high prevalence and MHI infections across endemic areas and the continuation of drug donations in perpetuity. Neither of these assumptions are still valid. The future will need to be different from the past, with donated drugs targeted to populations at risk in lower-income countries, while middle-income countries reduce the frequency of deworming where morbidity is controlled and purchase medicines for areas where population-level deworming is still indicated. In an environment of increasing country ownership and declining donated resources, allocating those resources should be optimized. Treatment and monitoring, and evaluation guidelines exist but are not always applied. To optimize the programs, there needs to be a transparent and defensible allocation of donated drugs and financial resources. With a restated alignment to the WHO NTD Road Map goal of eliminating morbidity from STH (defined as <2% MHI infection prevalence among children), stakeholders must develop a coordinated strategy to achieve and measure it. This will need to include an accountability/sustainability framework with consensus to apply it. With such a coordinated strategy, delivery and program monitoring objectives can be developed for each partner that considers the “who, where, what, and how” of program delivery. “Who” are the target groups at risk of morbidity? “Where” are they, “what” are the dominant parasite species, and what are the best treatment regimens for them? With this knowledge at hand, the “how” to reach the right people, in the right place, with the right drug(s) with high coverage and minimal cost can be addressed.

Global and national-level coordination between partners will improve efficiency, free up precious time for health care personnel, save money, reduce inadvertent duplication of effort, and allow integration of deworming not only with other NTD programs such as LF, schistosomiasis, and trachoma but also with immunization, maternal child health, and other primary healthcare activities. At this pivotal point in the global control program, improving collaboration and accountability within the global STH control program is crucial for continued success and investment. By fostering cooperation, accountability, and responsible resource allocation, we can address the persistent challenges faced by control efforts more effectively. To achieve this level of coordination, we must bring together key actors to reinforce commitments and create a unified strategy for STH control within the broader context of integrated healthcare initiatives.