It is an infectious disease that is caused by a parasite (Trypanosoma cruzi) that lives within the gut of the triatomine bug (Jurberg, 491).  The primary form of transmission is vector-borne.  As the bug feeds off the human blood, it defecates and the feces (which contain the parasite) get into the bloodstream and infect the person (Jurberg, 491).  However, transmission can occur in other ways, as well.  Blood transfusions, mother to infant transmission, eating contaminated food, and organ transplantation also contribute to infection rates (Rassi et al., 1388-9).