Trypanosomiasis.

African (sleeping sickness) and American (Chagas' disease) trypanosomiasis, caused by protozoa of the family Trypanosomatidae, are diseases that are endemic in parts of Africa and Latin America, respectively. Physicians in developed countries may occasionally see cases because of extensive travel and immigration from endemic countries. Although neurological involvement is common in both, its incidence and clinical presentation differ considerably. African trypanosomiasis, caused by subspecies of Trypanosoma brucei (T b rhodesiense, T b gambiense), is transmitted by the tsetse fly and causes meningoencephalitis, in which somnolence is a prominent feature. Parasites may reach the brain parenchyma through the choroid plexus or the Virchow Robin spaces. American trypanosomiasis, caused by Trypanosoma cruzi is transmitted by reduviid bugs. While lesions in the central nervous system are not prominent, except in the reactivated forms which occur in immunodeficient patients, the peripheral nerve, mainly the autonomic nervous system, is frequently involved, leading to the cardiomegaly and the digestive megaviscera. Congenital infections may also occur. In this paper we give an account of the epidemiology, clinical presentation and pathological features of these two protozoal infections based on human and experimental studies of both the central and peripheral nervous system.