The tropical diseases such as african sleeping sickness, chaga's disease, and leishmaniasis are caused by

African trypanosomiasis, also known as sleeping sickness, is a parasitic disease of humans and other animals. It is caused by protozoa of the species Trypanosoma brucei. There are two types that infect humans, Trypanosoma brucei gambiense (T.b.g) and Trypanosoma brucei rhodesiense (T.b.r.).

The answer is organisational websites.