Modeling the Potential Role of Engineered Symbiotic Bacteria in Malaria Control

Abstract

Recent experimental study suggests that the engineered symbiotic bacteria Serratia AS1 may provide a novel, effective and sustainable biocontrol of malaria. These recombinant bacteria have been shown to be able to rapidly disseminate throughout mosquito populations and to efficiently inhibit development of malaria parasites in mosquitoes in controlled laboratory experiments. In this paper, we develop a climate-based malaria model which involves both vertical and horizontal transmissions of the engineered Serratia AS1 bacteria in mosquito population. We show that the dynamics of the model system is totally determined by the vector reproduction ratio $R_\mathrm{v}$, and the basic reproduction ratio $R_0$. If $R_\mathrm{v}\le 1$, then the mosquito-free state is globally attractive. If $R_\mathrm{v}>1$ and $R_0\le 1$, then the disease-free periodic solution is globally attractive. If $R_\mathrm{v}>1$ and $R_0>1$, then the positive periodic solution is globally attractive. Numerically, we verify the obtained analytic result and evaluate the effects of releasing the engineered Serratia AS1 bacteria in field by conducting a case study for Douala, Cameroon. We find that ideally, by using Serratia AS1 alone, it takes at least 25 years to eliminate malaria from Douala. This implies that continued long-term investment is needed in the fight against malaria and confirms the necessity of integrating multiple control measures.