The infection by Trypanosoma cruzi, the aethiological agent of Chagas' disease, is
a serious public health problem in most of the Latin American countries. In Brazil, it is
estimated that around five million people are infected by T. cruzi and 25 million live in
areas of risk. In the South region of Brazil, the State of Rio Grande do Sul is the most
important endemic area of human Chagas' disease. The infection rate by T. cruzi in
different municipalities in the southern region of the state varies from 17.6% to 19.6%.
Characterization of several T. cruzi strains isolated from the wild and domestic
transmission cycles in Rio Grande do Sul shows that these parasite populations are highly
polymorphic, as demonstrated by isoenzyme and random amplified polymorphic DNA
analysis.
