Causative agent. American trypanosomiasis, or Chagas disease, is a protozoan zoonotic disease caused by the haemoflagellate Trypanosoma cruzi, (See previous figure) and is transmitted to humans either by blood-sucking triatomine vectors, blood transfusion or congenital transmission. This parasite infects over 150 species from 24 families of domestic and wild mammals, as well as humans. In the vertebrate host, T. cruzi infects many different cells, but in the human host, the disease is conspicuously limited to the myocardium and to gut nerve fibers (WHO, 2004a). Myocardial damage, as it develops during various phases of the Chagas’ Disease, is illustrated in the previous figure while the Chagas eye is illustrated in the adjacent figure.

Distribution . Chagas disease is present in 18 countries (see figure) on the American continent in two different ecological zones: the Southern Cone region, where the main vector lives inside human homes and in peri-domiciliary areas; and Central America and Mexico where the main vector species lives both inside dwellings and in uninhabited areas. Country-wide cross-sectional surveys in the 1980s found an overall prevalence of 17 million cases, with 4.8–5.4 million people exhibiting clinical symptoms, an annual incidence of 700,000-800,000 new cases and 45,000 deaths due to the cardiac form of the disease. Other studies indicate an infection prevalence of 13 million, with 3.0–3.3 million symptomatic cases and an annual incidence of 200,000 cases in 15 countries, with estimates of death around 50,000 people (WHO, 20004b; CDC, 2004)

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