Chagas disease (ChD) is a zoonotic protozoan infection caused by Trypanosoma cruzi and naturally transmitted by domestic and sylvatic blood-sucking triatomine bugs, known as “kissing bugs.” T. cruzi may be alternatively transmitted to humans congenitally, orally, or via transfusion and organ transplantation. Acute infection from vectorial transmission in endemic areas is mostly asymptomatic with high parasitemia, which generally becomes controlled in immunocompetent hosts after a few months. Without treatment, the infection pro- ceeds to the chronic phase, characterized by low-level parasitemia and poor response to treatment. Although most chronically infected patients do not develop clinical symp- toms (a period of clinical latency called indeterminate form), approximately 30% progress to irreversible cardiac, gastro- intestinal, and/or more rarely, peripheral nervous system disease characterized by the involvement of the autonomic nervous system and neuritis or the central nervous system. Heart disease is characterized by increasing arrhythmias or heart failure; sudden death is a characteristic of chronic ChD occurring in about 40% of patients with or without congestive heart failure. The digestive tract is affected in about 15% to 20% of chronic ChD patients who develop alteration of motility, secretion and absorption in the digestive tract, followed by increased calibre of the organ and increased difficulty in 3 emptying characteristics of megaoesophagus or megacolon. Endemic in Latin America (LA), ChD is considered a neglected tropical disease, where over 65 million people are at risk of exposure and 6 to 7 million people are infected. Thanks to efforts undertaken to control the vector and test the blood supply, the incidence and prevalence have decreased considerably in the past 20 years. Vector-control policies, screening of blood donors, and the screening and treatment of acute and chronic cases varies greatly among LA countries. Although universal screening of blood donors has been fully implemented in Brazil and Argentina, where the residual risk of infection is calculated to be around 1:200 000 units, in other countries, such as Mexico, there is no consensus on appropriate diagnostic methods for blood bank screening,and less than 20% of units were screened for T. cruzi antibodies. A comprehensive ChD surveillance program is not available in all countries. Consequently, there is wide geographic variation in reported infection rates, ranging from 1% to 25% and up to 60% in certain highly endemic Bolivian cities.
Risk of acquiring ChD from routine travel to endemic regions is quite low; risk factors include prolonged stays, rural areas, staying in thatched huts, and lower socioeconomic situations. A series of blood donors in the United States found that having spent 3 months or more in Mexico or Central and/or South America was associated with the highest odds of radioimmunoprecipitation assay–confirmed infection. Imported ChD is increasingly recognized as an emerging problem in the United States and Europe because of the immigration from LA. It is estimated that there are over 80 000 cases in Europe and over 300000 cases in the United States. Transmission of T. cruzi via blood and organ donors is a concern in both endemic and nonendemic countries. ChD in transplant recipients can result from organ or blood donor-derived infection, reactivation of chronic latent infection, or de novo infection posttransplant.
