Chagas disease is not always symptomatic. The disease is the result of infection with the Trypanosoma cruzi parasite and affects people who live or have lived in Latin America. Most people (up to 70%) infected with the parasite have the infection throughout their whole lives and never develop symptoms. In some people, however, the parasitic infection causes heart disease and digestive tract disorders. It is not known why certain patients develop symptoms while others do not.