Chagas Disease: Biology and Transmission of Trypanosoma cruzi

Abstract

In 1909, Carlos Justiniano Chagas first described the clinical manifestations of Chagas disease. The hemoflagellate parasite Trypanosoma cruzi (agent) is characterized by the presence of a flagellum and of a cytostome, glycosomes, reservosomes, and a nucleus in its cytoplasm. The life cycle of T. cruzi begins when a vector defecates on the skin of a host; the feces contain metacyclic trypomastigotes, which infect vertebrate cells. The vectors of this disease are members of the subfamily Triatominae, nocturnal, hematophagous insects capable of locating hosts by heat detection. T. cruzi infection has effects on the biology of the triatomine insect, its behavior, gut function, immune system, and associated microbiota. In the mammalian host, the parasite activates innate immune responses, and host cytokines are key to either control the infection or progress to chronicity. T. cruzi exhibits a wide genetic diversity, and while it has been proved under laboratory conditions to show varying degrees if virulence and organ tropism, no clear association has been found between specific strains and the clinical picture of the disease. This review addresses the history of the discovery of Chagas disease and discusses recent aspects of T. cruzi biology that provide insight into the dynamics of transmission.