There are two types of African trypanosomiasis (also called sleeping sickness); each is named for the region of Africa in which they are found. The disease is caused by a parasite named Trypanosoma brucei rhodesiense (tri-PAN-o-SO-ma BREW-see-eye rho-DEE-see-ense), carried by the tsetse fly. Worldwide, approximately 40,000 new cases of both East and West African trypanosomiasis are reported to the World Health Organization each year. However, the majority of cases are not reported due to a lack of infrastructure and it is likely that there are more than 100,000 new cases annually. Since 1967, twenty-one cases of East African trypanosomiasis have been reported within the United States, all among individuals who had traveled to Africa.