Discussion

Models assessing the acute phase of Trypanosoma cruzi infection, where parasitemia may be observed, are widely utilised, yet it is the chronic phase of infection that causes the debilitating effects of Chagas Disease (CD). Progression of disease from the indeterminate phase into the chronic phase of infection does not always occur and its cause is not well understood. The development of models allowing for the study of the indeterminate or chronic phases of infection may therefore prove useful in improving our understanding of CD progression. Our studies investigating the effects of genetic diversity on T. cruzi mono-infections in a mouse model found differences between the 10R26 and C8 clone 1 isolates, in both consequences of immune suppression and reinfection. Disease progressions observed within these models appear to mimic the indeterminate phase of infection where clinical symptoms and host morbidity are absent but the parasite is present within host organs. For the two isolates, decreased overall body condition and increased host morbidity were induced by immune suppression and/or reinfection, suggestive of either disease progression into a ?chronic phase? of infection or reactivation of disease with an absence in detectable parasitemia. These findings are clinically relevant to increasing our understanding of of the factors affecting the disease progression and exacerbation of CD.