(4) tse-tse fly Explanation: Human African tiypanosomia.sis, sleeping sickness, African lethargy, or Congo trypanosomiasis is a parasitic disease of people and animals, caused by protozoa of the species Trypanosoma. brucei and transmitted by the tsetse fly. It results in swelling of the brain. The disease is endemic in some regions of subSaharan Africa, covering areas in about 37 countries containing more than 60 million people. An estimated 50,000 to 70,000 people are currently infected, the number having declined somewhat in recent years.