How can the increased spread of infectious diseases in tropical countries be explained?

How can the increased spread of infectious diseases in tropical countries be explained? What natural factors contribute to this?

The warm and humid climate of tropical countries is ideal for the development of microorganisms that cause infectious diseases. The developing countries of the world are located in these regions of the globe. The population of these countries consumes poor-quality water, due to their lack of education, they do not observe the rules of personal hygiene. The peculiarities of the life of some African peoples, for example, does not imply the use of water for washing the body. Overcrowded cities, lack of sewerage and waste disposal only contribute to the multiplication of pathogens. Medical services leave much to be desired, often people do not receive any medical assistance.