This broad medical field is concerned with the prevention, diagnosis and treatment of diseases that afflict people who live in or visit tropical areas of the world. Tropical diseases include malaria, sleeping sickness, visceral leishmaniasis, amoebiasis, giardia intestinalis, typhoid, leprosy, tuberculosis, HIV/AIDS, yellow fever, schistosomiasis, filariasis, trachoma, onchocerciasis and other parasitic diseases. The field also concerns itself with international health policies, health economics, and epidemiology.