<unk>  (NTDs) are a diverse group of tropical infections that are common in low-income populations in developing regions of Africa, Asia, and the Americas. They are caused by a variety of pathogens, such as viruses, bacteria, protozoa and parasitic worms (helminths). These diseases are contrasted with the "big three" infectious diseases (HIV/AIDS, tuberculosis, and malaria), which generally receive greater treatment and research funding. In sub-Saharan Africa, the effect of<unk>  as a group is comparable to that of malaria and tuberculosis. NTD co-infection can also make HIV/AIDS and tuberculosis more deadly. In some cases, the treatments are relatively inexpensive. For example, the treatment for schistosomiasis is US$0.20 per child per year. Nevertheless, in 2010 it was estimated that control of<unk>  diseases would require funding of between US$2 billion and $3 billion over the subsequent five to seven years. Some pharmaceutical companies have committed to donating all the drug therapies required, and mass drug administration (for example, mass deworming) has been successfully accomplished in several countries. However, preventive measures are often more accessible in the developed world, but not universally available in poorer areas. Within developed countries,<unk>  affect the very poorest in society. In the United States, there are up to 1.46 million families, including 2.8 million children, living on less than two dollars a day. In developed countries, the burdens of<unk>  are often overshadowed by other public health issues. However, many of the same issues put populations at risk in developed as developing nations. For example, other problems can stem from poverty which expose individuals to the vectors of these disease, such as lack of adequate housing. Twenty<unk>  are prioritized by the World Health Organization (WHO), though other organizations define NTDs differently. Chromoblastomycosis and other deep mycoses, scabies and other ectoparasites and snakebite envenomation were added to the list in 2017. These diseases are common in 149 countries, affecting more than 1.4 billion people (including more than 500 million children) and costing developing economies billions of dollars every year. They resulted in 142,000 deaths in 2013—down from 204,000 deaths in 1990. Of these 20, two were targeted for eradication (dracunculiasis (guinea-worm disease) by 2015 and yaws by 2020), and four for elimination (blinding trachoma, human African trypanosomiasis, leprosy, and lymphatic filariasis) by 2020.
Neglected tropical diseases
Vaccine-preventable diseases
Waterborne diseases
Climate change and infectious diseases
Native American disease and epidemics
Infectious diseases 
Tropical disease
Drug pollution