Why are infectious diseases more common in the tropics?

As a result of increased human mobility and climate-driven vector movement, several tropical diseases began to spread into temperate climates. Poverty, a lack of clean water, and a lack of medical treatment all influenced the impact of a wide variety of tropical diseases. Exploration of tropical rainforests by humans, deforestation, rising immigration, and greater international air travel and other tourism to tropical regions have resulted in an increase in the occurrence of such diseases in non-tropical countries. Asia currently has the highest number of NTDs, followed by the huge emerging market economies of India, Indonesia and China. Pathogens of various varieties can be found in developing countries; poverty and hunger exacerbate the severity of prevalent diseases; and pathogen transmission is facilitated by poor infrastructure (e.g., water supply, sewage system and hospital hygiene). 

Dengue fever, yellow fever, rotavirus, AIDS, Ebola and Lassa fever are examples of viral tropical infections. Cholera, E. coli, TB, and Hansen's disease are examples of bacterial tropical illnesses (leprosy). Tropical infections can also be spread by parasitic single-celled protozoa and worms. Even without vaccines, neglected tropical diseases (NTDs) are highly avoidable. Guinea-worm disease, schistosomiasis, soil-transmitted helminthiasis, and trachoma can all be avoided with clean water, hygienic food handling, and basic hygiene. Draining wetlands to minimise insect and other vector populations or adding natural predators to control vector numbers. Insecticides and/or insect repellents are applied to strategic surfaces such clothing, skin, buildings, insect homes and bed nets. Because certain tropical mosquito species feed primarily at night, using a mosquito net over a bed (also known as a "bed net") helps prevent overnight transmission.

Tropical diseases and vectors are spreading to greater altitudes in mountainous regions, as well as to higher latitudes that were previously unaffected, such as the Southern United States, the Mediterranean region, and so on, thanks to climate change and the greenhouse effect.. Global warming has allowed Chytridiomycosis, a tropical disease, to flourish in Costa Rica's Monteverde cloud forest, causing amphibian populations of the Monteverde Harlequin frog to plummet. Global warming increased the heights of orographic cloud production in this area, resulting in cloud cover that aided the growth of the implicated disease.