Chagas Heart Disease

Chagas disease (CD) or American trypanosomiasis is a complex zoonosis produced by the infection with the intracellular protozoan parasite Trypanosoma cruzi. Although the disease was first described in 1909 by the Brazilian physician Carlos Chagas, this disease affects human beings since antiquity as it was demonstrated by paleoparasitology studies which proved the presence of DNA in mummies dating back to 9000 years old (Aufderheide et al., 2004; Guhl et al., 1999). The parasite T. cruzi is a hemoflagellate protozoan belonging to the Mastigophora class, Kinetoplastida order, Trypanosomatidae family, genus Trypanosoma, the group Stercoraria. It was named in honor of Oswaldo Cruz, who was the mentor of Carlos Chagas. T. cruzi has a complex life cycle involving two hosts, an invertebrate, especially an insect vector and some vertebrates, including man and domestic and wild reservoirs (Tyler & Engman, 2001). The presence of CD in humans is purely accidental, as when the man came into contact with natural foci and caused ecological imbalances causing the adaptation of vectors to human dwellings and new food sources. Thus three overlapping cycles were established: the wild cycle, the peridomestic cycle and the domestic cycle (Coura, 2007). The parasite occurs in a variety of hosts and infects 150 species from 24 families of domestic (e.g., dogs, cats and guinea pigs) and wild animals (e.g., rodents, marsupials, and armadillos) (Rassi, et al., 2010). The vectors involved in the transmission of CD are insects of the Phylum Arthropoda, Class Insecta, Order Hemiptera, Family Reduviidae, belonging to the subfamily Triatominae. There have been reported approximately 130 species of wild and domiciliary triatomines although only a handful is the competent vector for T. cruzi (Schofield, 1981). The domestic species mainly colonize rural homes and peri-urban areas and these species are responsible for most human cases of Chagas disease in endemic areas. Sylvatic species are inhabitants of strict wild habitats such as cracks of rocks, bird nests or burrows of mammals and caves, among others. Rhodnius prolixus is the main domestic vector in the northern countries of South America and Central America, Triatoma dimidiata in Central America and Triatoma infestans in countries of the southern of South America (Guhl, 2007), these species are well adapted to human habitation. T. cruzi presents four different morphological and biological forms: epimastigote, a replicative form located in the mid gut of the insect vector, it is the predominant form in the axenic culture; metacyclic trypomastigote develops in the posterior intestine and rectum of the insect vector and is the infective form; amastigote replicative stage, is located in the