African Trypanosomiasis (African Sleeping Sickness; Human African Trypanosomiasis; HAT) By Chelsea Marie, PhD, University of Virginia; William A Petri, Jr, MD, PhD, University of Virginia School of Medicine Reviewed / Revised Dec 2022 View Patient Education Pathophysiology Symptoms and Signs Diagnosis Treatment Prevention Key Points More Information Topic Resources Trypanosoma brucei gambiense Human African trypanosomiasis is infection with protozoa of the species Trypanosoma brucei, transmitted by the bite of a tsetse fly.