Keywords

1 Introduction

Neglected tropical diseases (NTDs) are a heterogeneous set of 20 diseases and disease groups (Table 16.1) that are transmitted in tropical and subtropical areas where they affect impoverished populations [1]. NTDs thrive in areas where sanitation is poor, and populations have close contact with infectious vectors and infected animals. More than 1 billion people are infected with one or more NTD [1].

Table 16.1 The 20 NTDs, their main causative agent and the WHO target for 2030
Full size table

2 Global Burden and Challenges

NTDs have been chronically overlooked by global policymakers and donor agencies, by the national health agendas of endemic countries and, sometimes, even by affected communities themselves for two main reasons:

  1. 1.

    NTDs cause relatively low numbers of deaths compared with the “three big killers” (malaria, HIV and TB) which, since the 1990s, have attracted the largest share of attention from global policymakers and, consequently, most of the financial investment by donors.

  2. 2.

    Each of the 20 NTDs “individually” causes limited morbidity.

3 Strategic Approach

Under the guidance of the WHO Department of Control of Neglected Tropical Diseases, that was created in 2005 with the aim of reverting this situation, intensive advocacy has been organized to promote that:

  1. 1.

    Despite their relatively low mortality, NTDs cause significant morbidity: they debilitate, deform and blind infected individuals. They disable through both overt (skin and eye lesions, internal organ lesions, limb deformation, impairment and retardation of mental functions) and silent morbidity (energy deficits, anaemia, growth retardation, chronic pain, exercise intolerance), with the potential to stunt the social, educational and professional lives of affected individuals.

  2. 2.

    Collectively, NTDs cause a loss of DALYs that is in the same order of magnitude as the three big killers (Fig. 16.1) [2].

  3. 3.

    Interventions to control NTDs are simpler and of lower cost than those to control the three big killers; in addition, they can be easily integrated among themselves or with existing platforms to further reduce control costs.

Fig. 16.1
A visualization chart of local burden of diseases. It is divided into 3 segments of different sizes and colors. In the largest segment, some of the diseases are stroke, diabetes, headaches, and cirrhosis. In the second largest segment, some of the diseases are H I V, T B and diarrhea. N T D is highlighted. In the smallest segment are road injections, falls, and violence, among others.

Relevance of NTDs in the global burden of diseases; the total weight of NTDs is presented in yellow; the circles present the individual weights of each NTD. (Source: Institute for Health Metrics Evaluation [2]. Used with permission. All rights reserved)

Full size image

This advocacy effort has resulted in a progressive intensification of the control activities that reach over a billion people every year [3].

4 Interventions for Prevention and Control

WHO recommends five core interventions to control NTDs.

Preventive chemotherapy is the regular, large-scale administration of medicines to entire population groups with the aim of reducing transmission or associated morbidity. Individual diagnosis is not necessary: surveys are conducted to assess if the disease is endemic in the area (community diagnosis), and if so, community treatment is organized. This approach is effective and easy to administer using safe, low-cost medicines; the treatment of uninfected individuals is without risk [4]. This approach is recommended for the following NTDs: lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiases, trachoma and yaws.

Innovative and intensified disease management is applicable to diseases which require a more traditional clinical approach entailing proper diagnosis and treatment rather than large-scale distribution of medicines. This “individual” approach (as opposed to the “community” approach of preventive chemotherapy) is justified by two main considerations: (1) the infectious agents that transmit these diseases are able to produce severe and possibly lethal outcomes, and infected individuals should therefore be carefully cared for and completely cured; (2) the treatment of such diseases necessitates long and complex treatment courses, specialized equipment and highly toxic medicines. These considerations mandate an approach involving close, individual, clinical case-management and follow-up of the patient by an experienced physician or nurse [5]. This approach is recommended for the following NTDs: Buruli ulcer, Chagas disease, human African trypanosomiasis, leishmaniasis, leprosy and snakebite envenoming.

Vector control is the reduction or elimination of the vectors that transmit infectious diseases using multiple strategies that entail environmental, chemical and biological control, and reduction of contacts between vectors and humans. This approach is recommended for the following vector-borne NTDs: Chagas disease, dengue, chikungunya, dracunculiasis, human African trypanosomiasis, lymphatic filariasis, onchocerciasis, schistosomiasis and trachoma.

Veterinary public health measures, such as vaccination or treatment of livestock and domestic animals, safe slaughtering and rodent control, are used to target NTDs for which animals play an active role in transmission. This approach is recommended for diseases such as rabies, echinococcosis, foodborne trematodiases, human African trypanosomiasis, leishmaniasis, taeniasis and cysticercosis.

Provision of safe water and sanitation is the improvement of water and sanitation services to levels that improve general hygiene living conditions and impede environmental contamination with human excreta. This approach is applicable to most of the NTDs because it reduces not only NTD-associated morbidity but also that of several other infections.

5 Role of WHO in the Control of NTDs

WHO is the specialized agency of the United Nations responsible for directing and coordinating international public health. Aside from its normative role in developing technical guidance and recommendations, WHO has two additional main tasks: advocacy and technical support to Member States.

NTD advocacy consists in raising the international level of attention and interest for NTDs: documenting the burden of NTDs and the benefits resulting from their control; promoting the inclusion of NTDs into public health agendas at national and international levels; sensitizing potential supporting institutions (bilateral cooperation agencies, public and private foundations and pharmaceutical companies or firms interested in corporate social responsibility); and coordinating all the actors involved in combating NTDs through the establishment of global partnerships and the organization of regular meetings [5].

WHO provides technical support to Member States upon request by national governments. This support concerns the development of national plans of action based on WHO strategies and recommendations but adapted to the country’s prevailing conditions and specificities; the implementation of disease-control activities; and the supervision, monitoring, evaluation and validation of such activities. Technical support is a key role of WHO, which has to be considered as a technical support agency rather than a funding agency. This implies that WHO does not cover the expenses related to implementation of national policies but does assure that implementation meets agreed technical standards. Furthermore, by leveraging its network of partners, WHO can facilitate resource mobilization from third parties willing to support the efforts of national governments [5].