As the world has wrestled with the immense challenges posed by COVID-19, HIV/AIDS, tuberculosis, and malaria, another group of diseases continues to exact a devastating toll largely out of view. Neglected Tropical Diseases (NTDs) affect more than 1 billion people, while an estimated 1.5 billion people require interventions, both preventive and curative. These diseases cause chronic disability, disfigurement, and death, yet receive only a fraction of the global health attention and funding they deserve. NTDs are not confined to any one region but span continents and impact some of the most marginalised and vulnerable populations globally. Their persistent neglect represents a systemic failure in international health priorities, despite the availability of effective prevention and treatment methods.
NTDs are not ignored by happenstance. Their marginalisation in global health policy reflects decades of systemic neglect rooted in colonial-era public health priorities and post-colonial donor strategies that favoured diseases with immediate mortality impact or economic threat. During the 20th century, diseases like malaria and tuberculosis dominated funding due to their acute lethality and threat to colonial and emerging economies. Conversely, NTDs, often chronic, disabling conditions affecting the poorest communities, were relegated to the sidelines.
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Donor fatigue and limited commercial interest further compounded the issue. Pharmaceutical companies have historically overlooked NTDs due to low profitability in affected regions, leaving these diseases dependent on underfunded government programmes and fragmented NGO efforts. The result has been a sustained cycle of invisibility, where these diseases persist silently amidst global health crises commanding headlines.
More Than Just a Regional Problem
While Africa carries a significant portion of the global NTD burden, these diseases also afflict large populations in Asia, Latin America, and parts of the Middle East. India, for example, reports nearly 100,000 new cases of leprosy annually, accounting for nearly half of all new cases worldwide. Brazil and other Latin American countries continue to face endemic Chagas disease, with an estimated 1.5 million people infected, while Southeast Asia grapples with dengue fever, lymphatic filariasis, and soil-transmitted helminths.
NTDs thrive in environments characterised by poor sanitation, inadequate healthcare access, and extreme poverty, conditions found in urban slums, rural villages, and conflict zones across the globe. Climate change and rapid urbanisation are expanding the geographical reach of these diseases, introducing new challenges in countries previously unaffected or with low endemicity.
Why NTDs Lack Urgency
The nature of NTDs contributes to their neglect. Unlike diseases that cause rapid death, NTDs often manifest as chronic, progressive conditions that cause disability, social stigma, and economic hardship over years or decades. Diseases such as lymphatic filariasis cause disfiguring elephantiasis, while trachoma can lead to blindness if untreated.
Transmission vectors vary, from parasitic worms transmitted by contaminated water or soil to insect vectors like mosquitoes, sandflies, and triatomine bugs. Many NTDs can be prevented or controlled through relatively simple interventions, such as improved water and sanitation, vector control, and mass drug administration (MDA). However, lack of infrastructure, insufficient funding, and weak health systems impede widespread implementation.
The Market’s Failure to Deliver
The pharmaceutical industry’s lack of investment in NTD research and development remains a major barrier. Less than 0.6% of global health R&D expenditure is allocated to NTDs. This stark underinvestment results in limited new treatment options and slows progress toward eradication goals.
To bridge this gap, public-private partnerships have emerged. The Drugs for Neglected Diseases initiative (DNDi) has led efforts to develop affordable treatments, including fexinidazole for sleeping sickness. Additionally, the WHO’s roadmap promotes innovation and access. Yet these efforts require greater scale and sustained funding to keep pace with the disease burden.
The Hidden Price of Inaction
The economic consequences of NTDs are profound and multifaceted. Beyond the direct costs of healthcare, NTDs undermine educational attainment, labour productivity, and economic development. Children infected with soil-transmitted helminths frequently suffer from malnutrition and cognitive delays, affecting schooling outcomes and future earnings.
According to the World Economic Forum, every dollar invested in the control and elimination of Neglected Tropical Diseases (NTDs) could yield between $27 and $42 in economic benefits. Another estimate suggests that addressing NTDs could restore approximately $600 billion in lost economic productivity by 2030, underscoring a missed opportunity to lift communities out of poverty. Persistent disability and stigma associated with these diseases also perpetuate social exclusion, further entrenching cycles of vulnerability.
Climate Change and Urbanisation
The epidemiology of NTDs is shifting due to environmental and demographic changes. Climate change alters vector habitats and transmission patterns, increasing risks in temperate zones previously unaffected by tropical diseases. For instance, warmer temperatures have expanded the range of Aedes mosquitoes, intensifying dengue outbreaks worldwide.
Simultaneously, rapid urbanisation, often accompanied by inadequate sanitation infrastructure, creates fertile grounds for diseases transmitted via contaminated water or poor hygiene. These evolving dynamics necessitate adaptive public health strategies combining surveillance, vector control, and community engagement.
Global Achievements and Challenges
International efforts to combat NTDs have gained momentum over the past decade. The WHO NTD Roadmap 2021–2030 sets ambitious targets for disease control and elimination, building on the 2012 London Declaration signed by governments, pharmaceutical companies, and NGOs.
Public-private partnerships play a pivotal role in advancing innovative solutions for Neglected Tropical Diseases (NTDs). Product development collaborations such as the Drugs for Neglected Diseases initiative (DNDi) and PATH have been instrumental in creating new diagnostic tools for diseases like lymphatic filariasis and onchocerciasis. These partnerships will remain critical in discovering and deploying novel treatments and strategies in the ongoing fight against NTDs.
Mass drug administration campaigns now reach over 1 billion people annually, contributing to significant reductions in disease prevalence. For example, Guinea worm disease is nearing eradication, and trachoma cases have decreased by 91% since 2002.
However, COVID-19 disrupted many NTD programmes, causing delays in treatment and surveillance. Funding shortfalls remain significant, with estimates suggesting a gap of over $1 billion annually to meet elimination goals. Political will and sustained investment are crucial to prevent reversals and accelerate progress.
Why NTDs Must Be Prioritised
NTDs disproportionately affect the poorest and most vulnerable, violating the principles of health equity and social justice. Prioritising NTD control aligns with the Sustainable Development Goals, particularly those targeting poverty reduction, health, education, and clean water and sanitation.
Moreover, addressing NTDs yields wide-reaching benefits for global health security by strengthening health systems, improving surveillance capacity, and fostering community resilience. Failure to invest in NTDs risks perpetuating cycles of poverty and ill health that undermine broader development efforts.
Breaking the Cycle of Neglect
Neglected tropical diseases represent a glaring failure in global health priorities, an invisible crisis that demands urgent attention. Their continued neglect reflects systemic inequities in funding, innovation, and political commitment. Yet, these diseases are preventable and controllable with existing tools and strategies.
The world must commit to sustained investment, innovation, and integrated action to bring NTDs out of the shadows. Doing so is not only a moral imperative but also a practical necessity for building healthier, more equitable societies worldwide.
