The protozoan Trypanosoma cruzi causes Chagas disease, which affects more than 30 million individuals, with approximately 100 million at risk in Latin America. Figure 1 shows the distribution of Chagas disease in the Americas. This disease is prevalent only in Central and South America, particularly in Argentina, Chile, Brazil, and Bolivia. It also occurs in the southern United States, however, where more than 90,000 Latin Americans are believed to be infected. The risk of transmission in the United States is mainly by blood transfusion by this immigrant population.
A. Transmission
Chagas disease is transmitted to children and young adults less than age 20 through the bite of a bug (reduviid, subfamily Triatominae). The bug becomes infected by feeding on infected animals such as the armadillo, opossum, raccoon, and skunks. Domestic dogs and cats also provide an extensive reduviid reservoir for infecting entire families.
The biting bug unfortunately dwells in the roofs and walls of houses. During the night the bug drops onto the sleeping individual and inflicts bites around the eyes. Infection is transferred when the trypanosomes in the animals excrement enters the wounded skin or penetrates the conjunctiva. The protozoa multiplies and then migrates through most organs of the body including the myocardium, pericardium, liver, spleen, and brain. Chagas disease is primarily transmitted through blood trans¬fusions, and unfortunately screening of blood is finan¬cially not possible in the affected countries. The simple accomplishment of screening blood, building better homes, and screening cats and dogs would prevent the majority of infections.