Epidemiology of American trypanosomiasis (Chagas disease).

Trypanosoma cruzi, the cause of American trypanosomiasis, or Chagas disease, is a protozoan parasite that is enzootic and endemic in much of the Americas, where it infects a wide variety of wild and domestic mammals as well as many species of triatomine vectors, in addition to humans. Historically, vector-borne transmission of T. cruzi has been the most important mechanism through which humans have become infected with the parasite, but transmission by blood transfusion and congenital transmission also have been important. In many of the endemic countries transmission of T. cruzi has improved markedly in recent years as vector control and donor screening programs have been implemented on a widespread basis. In the United States autochthonous transmission of T. cruzi appears to be extremely rare. Five persons are known to have become infected with T. cruzi through organ transplants here, and prior to the implementation of blood donor screening in 2007 five instances of transmission by transfusion had been reported. Current estimates put the total number of T. cruzi-infected persons living in the United States at 300,000, essentially all of whom are immigrants from the endemic countries. The obstacles that stand in the way of the total elimination of T. cruzi transmission throughout the endemic range are economic and political, and no major technological advances are needed to accomplish this goal.