Chagas disease is a tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. T. cruzi is commonly transmitted to humans and other mammals by an insect vector, the blood-sucking assassin bugs of the subfamily Triatominae. The disease may also be spread through blood transfusion and organ transplantation, ingestion of food contaminated with parasites, and from a mother to her fetus.The symptoms vary over the course of the infection. In the early, acute stage, symptoms are mild and usually produce no more than local swelling at the site of infection. As the disease progresses, over the course of many years, serious chronic symptoms can appear, such as heart disease and malformation of the intestines. If untreated, the chronic disease is often fatal. Current drug treatments are generally unsatisfactory; available medications are highly toxic and often ineffective, particularly those used to treat the chronic stage of the disease.Chagas disease occurs exclusively in the Americas. It is estimated that as many as 8 to 11 million people in Mexico, Central America, and South America have Chagas disease, most of whom do not know they are infected. Large-scale population movements from rural to urban areas of Latin America and to other regions of the world have increased the geographic distribution of Chagas disease.For product information, please refer to Trypanosoma cruzi.