African trypanosomiasis is an insect-borne parasitic infection of humans and other animals caused by the protozoan species Trypanosoma brucei, which is transmitted by the bite of an infected tsetse fly. Human African trypanosomiasis (HAT) is also known as sleeping sickness. Humans are infected by two subspecies of T. brucei: T. brucei gambiense is primarily transmitted between humans and causes over 92% of cases, while T. brucei rhodesiense is zoonotic, with animals such as cattle serving as reservoirs.