The answer is tsetse fly.
African sleeping sickness is a disease caused by Trypanozoma brucei, a species of protozoa. The protozoic parasite is transmitted by a tsetse fly. When the tsetse fly bites the host, parasites enter the lymphatic system and then bloodstream. The first symptoms are itchiness, fever, headaches, and later the sleeping problems occur. The disease can even include dysfunction in cardiac, endocrine, or excretory systems.