Vector consumption and contact process saturation in sylvatic transmission of T. cruzi
Abstract
Recent research in the transmission of the protozoan parasite Trypanosoma cruzi,
some strains of which cause Chagas’ disease, suggests that consumption of vectors
by sylvatic hosts such as raccoons may play a role in maintaining the transmission
cycle in the wild. As both hosts and vectors have been observed to invade new ecological
niches, it is important to consider the effect vector consumption may have
on vector density. For this reason a per individual contact rate is employed which
rises roughly linearly for low vector densities and saturates for high densities. The
model under study thus superimposes a predator-prey structure on a host-vector
infection cycle (with first one, and then multiple, hosts). Outbreak behavior follows
classical threshold behavior through the reproductive number R0, which allows
evaluation of the importance of this transmission avenue relative to the traditional
route. For sufficiently sharp contact rate saturation, two locally stable vector densities
may exist.