GLOBAL BURDEN OF DISEASE
The major tropical infections of humans include malaria and other protozoan infections (e.g., amebiasis, human African trypanosomiasis, Chagas disease, and leishmaniasis), helminth infections (e.g., dracunculiasis, lymphatic filariasis, onchocerciasis, schistosomiasis, and soil- transmitted helminthiases), emerging arboviral (e.g., dengue and Japanese encephalitis), and hemorrhagic fever virus infections (e.g., Ebola and Marburg viruses), and specific bacterial infections (e.g., Buruli ulcer, leprosy, melioidosis, and trachoma).
As shown in Table 17.1, the tropical diseases represent some of the most common infections of humankind, with the three major soil-transmitted helminthiases (ascariasis, hookworm, and trichuriasis) exhibiting the greatest prevalence, followed by malaria, schistosomiasis, and lymphatic filariasis. Up to one-eighth of the world's population is infected with a tropical disease. The people at greatest risk for acquiring tropical diseases are the estimated 2.7 billion people who live on less than $2 per day. For the most part, the tropical diseases are diseases of poverty and are found almost exclusively in low- and middle-income countries of sub-Saharan Africa, Asia, and Latin America. In these regions, it is common for a single individual to be simultaneously afflicted with several tropical diseases. For instance, it would not be unusual for a school-aged child in Vietnam to be polyparasitized with all three major soil-transmitted helminths, while a pregnant woman in sub-Saharan Africa might be simultaneously infected with malaria, schistosomiasis, and hookworm.
The tropical diseases have a significant impact on the health and well-being of the world's poorest people living in the developing world.