Sustainable access to deworming drugs in a changing landscape

Eliminating morbidity caused by neglected tropical diseases by 2030

The objective of this manuscript is to provide selective examples of the work of the Pan American Health Organization/World Health Organization (PAHO/WHO) Collaborating Centre for Research and Training in Parasite Epidemiology and Control which contribute to the WHO goal of eliminating neglected tropical diseases by 2030. This PAHO/WHO CC specifically aligns its activities with the Sustainable Development Goals and with the goals outlined in the WHO Road Map for Neglected Tropical Diseases 2021-2030. Its role is to contribute to advancing global action on NTDs, primarily through policy development and knowledge translation. Three important projects have recently been completed: 1. Finalizing the Monitoring and Evaluation Framework for the NTD Road Map (published May 2021; this PAHO/WHO CC was a member of the working group); 2. Developing new guidelines for the preventive chemotherapy of Taenia solium taeniasis (published September 2021; this PAHO/WHO CC was co-Chair; and 3. Formulating a policy brief on deworming for adolescent girls and women of reproductive age (published January 2022; this PAHO/WHO CC is co-lead). These projects are the result of the integration of expertise and experience from multiple partners, including from PAHO and WHO (where both organizations provided key leadership), this PAHO/WHO CC, government ministries, civil society organizations and universities, among others. In conclusion, this PAHO/WHO CC contributes timely guidance to country-led evidence-informed public health policy, to cost-effective program implementation and to the identification of priority research topics - all focused, ultimately, on eliminating NTD-attributable morbidity by 2030.

The yin and yang of human soil-transmitted helminth infections

The major soil-transmitted helminths that infect humans are the roundworms, whipworms and hookworms. Soil-transmitted helminth infections rank among the most important neglected tropical diseases in terms of morbidity, and almost one billion people are still infected with at least one species. While anthelmintic drugs are available, they do not offer long term protection against reinfection, precipitating the need for vaccines that provide long-term immunologic defense. Vaccine discovery and development is in advanced clinical development for hookworm infection, with a bivalent human hookworm vaccine in clinical trials in Brazil and Africa, but is in its infancy for both roundworm (ascariasis) and whipworm (trichuriasis) infections. One of the greatest hurdles to developing soil-transmitted helminth vaccines is the potent immunoregulatory properties of these helminths, creating a barrier to the induction of meaningful long-term protective immunity. While challenging for vaccinologists, this phenomenon presents unique opportunities to develop an entirely new class of anti-inflammatory drugs that capitalise on these immunomodulatory strategies. Epidemiologic studies and clinical trials employing experimental soil-transmitted helminth challenge models, when coupled with findings from animal models, show that at least some soil-transmitted helminth-derived molecules can protect against the onset of autoimmune, allergic and metabolic disorders, and several natural products with the desired bioactivity have been isolated and tested in pre-clinical settings. The yin and yang of soil-transmitted helminth infections reflect both the urgency for effective vaccines and the potential for new immunoregulatory molecules from parasite products.

Recombinant Paraprobiotics as a New Paradigm for Treating Gastrointestinal Nematode Parasites of Humans

Gastrointestinal nematodes (GINs) of humans, e.g., hookworms, negatively impact childhood growth, cognition, nutrition, educational attainment, income, productivity, and pregnancy. Hundreds of millions of people are targeted with mass drug administration (MDA) of donated benzimidazole anthelmintics.

Gastrointestinal nematodes (GINs) of humans, e.g., hookworms, negatively impact childhood growth, cognition, nutrition, educational attainment, income, productivity, and pregnancy. Hundreds of millions of people are targeted with mass drug administration (MDA) of donated benzimidazole anthelmintics. However, benzimidazole efficacy against GINs is suboptimal, and reduced/low efficacy has been seen. Developing an anthelmintic for human MDA is daunting: it must be safe, effective, inexpensive, stable without a cold chain, and massively scalable. Bacillus thuringiensis crystal protein 5B (Cry5B) has anthelmintic properties that could fill this void. Here, we developed an active pharmaceutical ingredient (API) containing B. thuringiensis Cry5B compatible with MDA. We expressed Cry5B in asporogenous B. thuringiensis during vegetative phase, forming cytosolic crystals. These bacteria with cytosolic crystals (BaCC) were rendered inviable (inactivated BaCC [IBaCC]) with food-grade essential oils. IBaCC potency was validated in vitro against nematodes. IBaCC was also potent in vivo against human hookworm infections in hamsters. IBaCC production was successfully scaled to 350 liters at a contract manufacturing facility. A simple fit-for-purpose formulation to protect against stomach digestion and powdered IBaCC were successfully made and used against GINs in hamsters and mice. A pilot histopathology study and blood chemistry workup showed that five daily consecutive doses of 200 mg/kg body weight Cry5B IBaCC (the curative single dose is 40 mg/kg) was nontoxic to hamsters and completely safe. IBaCC is a safe, inexpensive, highly effective, easy-to-manufacture, and scalable anthelmintic that is practical for MDA and represents a new paradigm for treating human GINs.

Estimated need for anthelminthic medicines to control soil-transmitted helminthiases in school-aged children, 2020-2030

Background

Soil-transmitted helminthiases (STH) are part of the group of neglected tropical diseases traditionally treated with preventive chemotherapy interventions. In recent years, drug donations have been essential to expanding preventive chemotherapy and achieving progressive control of morbidity from STH. This study aims to evaluate the need for anthelminthic medicines during 2020–2030.

Methods

To estimate the need for anthelminthic medicines, we considered three different scenarios: (1) the control programmes continues to expand coverage and maintains the frequency of drug administration established at baseline; (2) the programmes continues to expand coverage but adapts the frequency of drug administration when the STH prevalence is reduced and (3) the STH programme becomes self-sustainable in some endemic countries.

Results

We estimate that the number of anthelmintic medicines needed to treat school-aged children will increase by 40% by 2025 and by 52% by 2030 if countries do not change the frequency of preventive chemotherapy (scenario 1); that the number of tablets needed will reduce by 32.4% by 2025 and by 49.1% in 2030 if endemic countries reduce the frequency of preventive chemotherapy (scenario 2); and drug donations could be reduced by 54.4% by 2025 and 74.4% by 2030 if some endemic countries could become independent in drug procurement (scenario 3).

Conclusions

The number of anthelmintic medicines needed to achieve elimination of morbidity due to STH in school-aged children will decline during 2020–2030. The decline will be substantial if a number of “upper-middle income” countries in which STH are endemic procure, as expected, anthelminthic medicines independently.

More medicines alone cannot ensure the treatment of neglected tropical diseases

Neglected tropical diseases afflict more than 1 billion of the world's poorest people. Pharmaceutical donations of preventive chemotherapy for neglected tropical diseases enable the largest en masse treatment campaigns globally with respect to the number of people targeted for treatment. However, the blanket distribution of medicines at no cost to individuals in need of treatment does not guarantee that those individuals are treated. In this Personal View, we aim to examine the next steps that need to be taken towards ensuring equitable treatment access, including health system integration and the role of endemic countries in ensuring medicines are delivered to patients. We argue that the expansion of medicine donation programmes and the development of new medicines are not the primary solutions to sustaining and expanding the growth of neglected tropical disease programmes. Treatment is often not verified by a medical professional, independent surveyor, or national programme officer. Additionally, access to medicines might not be equitable across at-risk populations, and treatment targets for disease control remain largely unmet within many endemic countries. To enable equitable access and efficient use of existing medicines, research is needed now on how best to integrate the treatment of neglected tropical diseases into local health systems. A comprehensive approach should be used, which combines mass drug administration with on-demand access to treatment. Increased commitment by endemic countries, when possible, around the ownership of treatment campaigns is essential to improve access to medicines for neglected tropical diseases.

Formative research to inform development of a new diagnostic for soil-transmitted helminths: Going beyond the laboratory to ensure access to a needed product

Soil-transmitted helminths (STHs) affect more than 1.5 billion people. The global strategy to control STH infections requires periodic mass drug administration (MDA) based on prevalence among populations at risk determined by diagnostic testing. Widely used copromicroscopy methods to detect infection, however, have low sensitivity as the prevalence and intensity of STH infections decline with repeated MDA. More sensitive diagnostic tools are needed to inform program decision-making. Using an integrated product development process, PATH conducted qualitative and quantitative formative research to inform the design and development of a more sensitive test for STH infections. The research, grounded in a conceptual framework for ensuring access to health products, involved stakeholder analysis, key opinion leader interviews, observational site visits of ongoing STH surveillance programs, and market research including market sizing, costing and willingness-to-pay analyses. Stakeholder analysis identified key groups and proposed strategic engagement of stakeholders during product development. Interviews highlighted features, motivations and concerns that are important for guiding design and implementation of new STH diagnostics. Process mapping outlined current STH surveillance workflows in Kenya and the Philippines. Market sizing in 2016 was estimated around half a million tests for lower STH burden countries, and 1-2 million tests for higher STH burden countries. The cost of commodities per patient for a molecular STH diagnostic may be around $10, 3-4 times higher than copromicroscopy methods, though savings may be possible in time and staffing requirements. The market is highly price sensitive as even at $5 per test, only 27% of respondents thought the test would be used by surveillance programs. A largely subsidized STH control strategy and a semi-functional Kato-Katz test may have created few incentives for manufacturers to innovate in STH diagnostics. Diverse partnerships, as well as balancing needs and expectations for new STH diagnostics are necessary to ensure access to needed products.

Exploring global and country-level barriers to an effective supply of leishmaniasis medicines and diagnostics in eastern Africa: a qualitative study

OBJECTIVES

To understand stakeholders' perceptions of the access barriers to quality-assured diagnostics and medicines for leishmaniasis in the high-burden region of eastern Africa, and to identify key bottlenecks to improve the supply of commodities for neglected tropical diseases.

DESIGN

Desk reviews and qualitative in-depth interview study with purposive sampling.

METHODS

A landscape analysis through literature and desk review was performed. Next, 29 representatives from international organisations, non-governmental agencies, national control programmes from six countries (Ethiopia, Kenya, Somalia, South Sudan, Sudan and Uganda) and manufacturers were interviewed between May and July 2018. Participants were selected purposively and expanded through a snowballing technique.Data analysis was aided by NVivo, applying the framework method as a part of the thematic content analysis approach.

RESULTS

The barriers along the visceral leishmaniasis (VL) supply chain were identified as emerging themes, grouped across supply chain activities and health systems component(s). Stakeholders expressed the perception of progress, but bottlenecks persist. VL medicines, in general, lack multisource production capacity and with small market volume, expansion of suppliers is difficult. Procurement is plagued by forecasting difficulties, complex regulatory policies and procedures, and distribution challenges. Weak communication and coordination across different levels resulted in shortages and loss of trust among different actors. Cross-cutting issues spanned from limited political and resource commitment due to low awareness and limited in-country capacity. However, study respondents were optimistic to pursue several remedies, most importantly to build bridges between supply and demand sides through continued dialogue and collaborations. Diagnostics supply has mostly been overlooked; thus, improved investment in this area is needed.

CONCLUSIONS

Addressing supply barriers in eastern Africa requires consistent, specific efforts at the global and national levels, progressing from current partnerships and agreements. Priority actions include pooled procurement, improved forecast, and increased commitment and resources. Sustainability remains an elusive goal, yet to be integrated into discussions moving forward.