The African trypanosomes are parasites of humans and domestic animals causing the disease African trypanosomiasis Trypanosomiasis, Animals, Trypanosomiasis, Man) or sleeping sickness. T. brucei gambiense infection occurs in Central and West Africa and is slowly progressive, and generalized. Initially the trypanosomes are present extracellularly in the subcutaneous tissue at the site of the bite of the tsetse fly and give rise to a papular and later ulcerating lesion, often called a chancre, which persists for about 2 weeks. In the second stage trypanosomes enter the bloodstream and multiply there. In the third stage there is fever and lymphoid hyperplasialeading to enlargement of the spleen and especially of the cervical lymph nodes, which contain trypanosomes useful for diagnosis by puncture and smear. The fourth stage is central nervous invasion associated with intermittent fever. Trypanosomes in the neuropil and the cerebrospinal fluid...