**1. Introduction**

Neglected tropical diseases (NTDs) can be caused by viruses, bacteria, parasites, fungi, and toxins. They occur mainly in tropical areas of 149 countries on the planet, mainly concentrated in Africa and Latin America, and are called "neglected" because at the political, health, and research levels, what is necessary has not been done to eliminate them, and, furthermore, the money allocated to serving them is practically nil. According to the World Health Organization (WHO), there are 20 NTDs and one-sixth of the world's population suffers from at least one of these diseases [1, 2]. The majority of the affected population live in poor socioeconomic conditions, with low income, low educational level, and precarious housing where, in addition to the

beliefs, attitudes and behaviors of these people cause social exclusion. NTDs predominate in tropical and humid climates, mainly in rural areas, conflict zones, and regions of difficult access. However, urban areas can also be affected. The presence of these diseases has been increasing due to factors such as climate change [3–5]. The absence of timely and accurate diagnoses, quality medical care, medicines, vaccines, and access to drinking water and sanitation services are the factors that increase the presence of NTDs and can only be faced with leadership and political effort economic as a whole since they do not top the list of priorities in public health policies. The development in the research of new and better medicines and diagnostic methods by the industry is very scarce. In addition, reliable statistical data makes it difficult for these diseases to be known by society [6–9].

These diseases are of increasing concern, as the geographic range of tropical diseases is expanding due to climate change, urbanization, changing agricultural practices, deforestation, and biodiversity loss [10]. Infectious diseases can be unpredictable with the potential risk of global outbreaks. However, the way we characterize pathogens has changed dramatically. Although increasingly sophisticated diagnostic tools have improved the ability to detect the presence of the pathogens that cause these diseases, this ability comprises only a small part of the set of tools necessary to generate an accurate etiological diagnosis to manage these health threats. For this, the ecoepidemiology of diseases must be taken into account, with an approach to the interdependence of individuals and their connection with the levels of individual, social, molecular, and environmental organization that participate in the causal processes of diseases [11, 12]. Over the years, molecular methods have evolved and improved, from conventional endpoint polymerase chain reaction (PCR) to real-time quantitative PCR (qPCR), DNA microarrays, digital droplet PCR (ddPCR), loopmediated isothermal amplification (LAMP), and metagenomic approaches based on high-throughput next-generation DNA sequencing (HT-NGS). Such technological achievements have contributed to expanding the set of analytical tools used to solve various research objectives, including disease diagnosis. The next-generation sequencing (NGS) has generated a trigger in the discovery and characterization of pathogens, leaving behind old culture methods and techniques and making it possible to detect non-culturable pathogens that were previously difficult to diagnose. On the other hand, due to its sensitivity and quantitative characteristics, digital polymerase chain reaction (dPCR) is a potential candidate to become an attractive new method among molecular technologies for parasite detection and quantitative analysis, favoring a better understanding of the transmission dynamics of the pathogens that cause these diseases [13–18].
