Abstract | Trypanosoma cruzi, the parasite that causes Chagas' disease, is endemic throughout the Americas (except Canada) in a sylvatic cycle involving hosts such as raccoons and woodrats. In Texas, two transmission cycles overlap, with distinct hosts, vectors, and distinct strains of the parasite. One strain, known to cause Chagas' disease in humans, extends into Mexico; the other, which extends east to Georgia, may be less virulent but is adapted to vertical transmission and provides cross-immunity against other strains. A multi-patch model measures the capacity of the latter strain to resist, through cross-immunity, "invasion" by the first strain. |