Introductory Chapter: Neglected Tropical Diseases – A Pending Issue

Abstract

Neglected Tropical Diseases (NTDs) are the result of changing patterns in health that have created gaps in the attention of specific problems in specific populations. As a result, today, over 1 billion inhabitants are at risk of being affected by these diseases in many parts of the world. This chapter highlights the importance of addressing Neglected Tropical Diseases and to prioritize its solutions in the long term. Although challenging, this is an issue that cannot be postponed in the global agenda and needs to be properly addressed with the implementation of comprehensive interventions for the ultimate benefit of those who are most vulnerable.

1. Introduction

Defined as the study of complex change in patterns of health and disease and on the interactions between these patterns and their demographic, economic and sociologic determinants, and consequences [1], epidemiologic transition has changed population health in the last century. This global phenomenon is characterized by two major components: (1) changes in population’s age distribution from younger to older and (2) changes in patterns of morbidity and mortality [2], being the shifting from infectious to noncommunicable diseases as the leading causes of mortality and disease burden, its most evident effect. As a result, new challenges arise, and priorities must be reshuffled to provide quality and effective health interventions.

Despite of today’s spectacular advances in public health, benefits have not reached all geographic regions at the same pace, creating mixed scenarios in which a double disease burden, one from new challenges typical from developing countries arise and other in which old unsolved problems remain [3]. These pockets of lagging conditions are ideal for the persistence of a group of diseases that remain major unsolved health problems. Those are the neglected tropical diseases (NTDs).

2. Neglected tropical diseases today

Neglected tropical diseases (NTDs) are a diverse group of diseases that occur in tropical and sub-tropical regions and are intimately linked to poverty and other social conditions [4]. Globally, one out of six inhabitants are at risk [5]; nonetheless, this frequency is not homogeneously distributed but focused instead on specific geographic regions such as sub-Saharan Africa, Asia, and Latin America.

The most recent list of NTDs includes Buruli ulcer, Chagas disease, dengue and chikungunya, dracunculiasis, echinococcosis, foodborne trematodiases, human African trypanosomiasis, leishmaniasis, leprosy, lymphatic filariasis, mycetoma, chromoblastomycosis and other deep mycoses, onchocerciasis, rabies, scabies and other ectoparasitoses, schistosomiasis, soil-transmitted helminthiases, snakebite envenoming, taeniasis and cysticercosis, trachoma, and yaws [6].

As for their impact in population’s health, NTDs not only account for mortality or morbidity but also are a cause of disabilities and other effects such as the impairment of the cognitive development of children which ultimately affect permanently the quality of life in those affected individuals. Finally, while considering both direct and indirect costs, they can easily be catastrophic for individuals and families.

3. The challenge and new tools for addressing neglected tropical diseases

Neglected tropical diseases (NTDs) are difficult to address due to multiple factors. As for their nature, they are a diverse group of bacterial, viral, fungal, and noncommunicable diseases with environmental components in their natural history that make difficult the design of stand-alone interventions. Very few of them have specific vaccines, or treatments that are widely available or easily deployable, and most require follow-up of the cases to achieve complete recovery.

Ideally, multiple and coordinated interventions are required over time to achieve the desired impact. Most interventions can be classified into three types: (1) preventive chemotherapy by mass drug administration, (2) innovative and intensified disease management, and (3) vector ecology and management. Many NTDs require all three types of interventions in a comprehensive approach for extended periods. This is expensive, as it represents the overall cost of billions of dollars every year; nonetheless, this approach has proven to be cost-effective [7].

Today, no country by itself can address NTDs as an isolated entity, as it requires sufficient resources and investments that not all countries can afford. Most of the research infrastructure and networks are not located in affected regions, and the countries with access to them (usually developed countries) not necessarily have NTDs at the top of their priorities; therefore, multilateralism and cooperation are also required.

Finally, understanding the social context is essential while addressing NTDs. Factors such as high poverty rate, large immigrant population, geographic proximity to endemic areas [8], and social unrest are common in many of the regions where NTDs are highly prevalent and need to be taken into consideration while planning and implementing interventions.

The World Health Organization endorsed by the 73rd World Health Assembly, the initiative Ending the neglect to attain the Sustainable Development Goals. Roadmap for neglected tropical diseases 2021–2030 [6], thus setting the starting point to a new priority in which all State members define their specific plans to address NTDs in the coming years.

In the meantime, science is one of the best allies for tackling NTDs. Once an NTD, malaria, is still today the main killer in the world. Until 2021, Malaria vaccine had been an elusive dream [9], but only 2 years later, the mass allocation of doses for the most affected countries in Africa is a reality that will deliver positive impacts in the coming years [10]. This step has taken over 40 years of research and considerable investment but has marked the trajectory that needs to be followed if we want to succeed in this pending issue.

4. Conclusions

Epidemiologic transition is a reality and a process that will continue to develop as societies evolve. The main task health systems will face in the future is to manage this transition in an orderly fashion for avoiding gaps and inequities that facilitate NTDs and simultaneously providing benefits to most of the population. This is no minor task as it requires planification, coordination, and most importantly long-term and persistent commitment, one that has been present only on a few occasions in public health history. More than a pending issue, NTDs existence in the 21st century is a general failure of our societies which needs to be properly addressed and solved.