The blood-stage dynamics of mixed Plasmodium malariae-Plasmodium falciparum infections

We present the first mathematical model of the within-host dynamics of a mi xed-species malaria infection in a human: the blood-stage population dynami cs of a dual infection with Plasmodium malariae and Plasmodium falciparum. Our results reproduce several important features of such infections in natu re, including the asymmetry of species asexual-form densities, inter-specif ic suppression through interactions with the human immune system, and seaso nal alternations in species prevalence. Most importantly, our results sugge st that an existing P. malariae infection can reduce the peak parasitemia o f a subsequent P. falciparum superinfection by as much as 50%. This result integrates numerous empirical observations and supports the hypothesis that clinical outcomes of P. falciparum infections may be influenced by the pre sence of a congener. (C) 1999 Academic Press.