The correct answer is Trypanosoma. ● The sleeping sickness is caused by microscopic parasites of the species Trypanosoma brucei. ● It is transmitted by the tsetse fly (Glossina species), which is found only in sub-Saharan Africa. ● Trypanosoma, any member of a genus (Trypanosoma) of parasitic zooflagellate protozoans belonging to the order Kinetoplastida. ● The adult trypanosomes are mainly blood parasites of vertebrates, especially fishes, birds, and mammals. ● Most species require an intermediate host (often an insect or a leech) to complete their life cycle. ● The other species of trypanosomes induce economically important disease s of livestock nagana, surra, mal de caderas, and dourine.