Differential drivers of intraspecific and interspecific competition
during malaria-helminth co-infection
Abstract
Various host and parasite factors interact to determine the outcome of
infection. We investigated the effects of initial infectious dose and
co-infection with a red blood cell-limiting helminth on the within-host
dynamics of murine malaria. Using a time-series approach to model the
within-host “epidemiology” of malaria, we found that increasing
initial dose reduced time to peak cell-to-cell parasite propagation, but
also reduced its magnitude, while helminth co-infection delayed peak
malaria propagation, except at the highest malaria doses. Using a
mechanistic model of within-host dynamics, we identified dose-dependence
in parameters describing host responses to malaria infection and
uncovered a plausible explanation of the observed differences during
co-infections: in co-infections, our model predicted a higher background
death rate of RBCs combined with greater influx of new RBCs. Such
interactions are key to understanding variation in disease severity, and
could inform field studies of malaria, where co-infection and low doses
are the norm.