African trypanosomiasis

African trypanosomiasis is an insect-borne parasitic infection of humans and other animals caused by the species Trypanosoma brucei, which is transmitted by the bite of an infected tsetse fly. 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. Human African trypanosomiasis (HAT) is also known as African sleeping sickness or simply sleeping sickness.

During the first stage of the disease, T. brucei parasites replicate in the blood and lymph, causing fever, headache, itchiness, and joint pains about one to three weeks after the bite. Weeks to months later, the parasite crosses the blood-brain barrier and the second stage begins with neurological symptoms including confusion, poor coordination, numbness, and trouble sleeping. Diagnosis involves detecting the parasite in a blood smear or lymph node fluid. A lumbar puncture is often needed to tell the difference between first- and second-stage disease. T. brucei gambiense causes chronic infection that can take months to years to develop symptoms, while T. brucei rhodesiense infection causes symptoms within weeks to months.