Mosquito Host Choice and the Epidemiology of Malaria

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Abstract
Several recent studies have demonstrated that blood-sucking mosquitoes may preferentially choose hosts infected with malarial parasites. I developed and analyzed a simple model for the dynamics of malarial transmission that incorporates such nonrandom feeding behavior by the mosquito. The dynamic variables of interest are the infected proportions of the human host and mosquito vector populations. I considered three types of nonrandom host choice; consistent preference for the infected host at all levels of host infection; increasing preference for infected hosts as the infection level of the host increases; and a switching behavior in which the mosquito switches preference from uninfected to infected hosts as the level of host infection increases. The results were compared with previous results from models with random host choice. Both the random-choice and consistent-preference models predict either a stable uninfected state or a stable persistence of the infection. For these models, increasing consistent host preference makes it easier to maintain a stable infection, relative to the random-choice model. However, increasing the strength of consistent host preference can either increase or decrease the equilibrium level of infection in the host population. The increasing-preference and switching-behavior model can produce model behavior in which there are two stable equilibria: one at the uninfected state; the other at a high level of host infection. In this case, the outcome of the malaria dynamics depends on the intial levels of infection in the most and vector populations. These results show that nonrandom host choice can have important quantitative and qualitative effects on the epidemiology of malarial transmission, suggesting that further study of such mosquito feeding behavior is warranted.