Curing By Infecting: Two-Strain Competition During The Acute Phase Of Chagas

SHIRLENE VEGA; GUSTAVO J. SIBONA; C. A. CONDAT

Santiago de Chile

Simposio; 11th International Symposium on Mathematical and Computational Biology; 2011

BIOMAT Consortium

Simultaneous occurrence of infections with two different T. cruzi lineages in the same individual has been reported in the literature. We have thus extended our model for the parasite – antibodies interaction during the acute phase of Chagas’ disease by considering the competition between two parasite strains and one antibody species. Our main result is the nonexistence of a simultaneous equilibrium between the immune system and both parasite strains. This suggests there is an indirect competition between the parasite populations in order to survive the immune system attack. The model yields six possible outcomes that can be grouped into three main cases: healing, chronic disease and host death. The second case is subdivided into two, depending on which strain survives, and the third case is subdivided into four, considering the different ways the populations may grow without control. Our results agree with the reported clinical observations: the coexistence of two T. cruzi strains has not been found in any hemocultural tests in infected organisms, even in those geographical locations where different strains circulate. Application of our model to experimental data shows how a first infection can provide immunity against subsequent infections. Moreover, it suggests that a similar but less infective strain could be used for vaccination.