Modelling the risk of mosquito-borne diseases by System Dynamics: The case of human travel between different geographic regions

This paper describes the development of a System Dynamics model to study the diffusion of diseases transmitted by the mosquito Aedes albopictus, considering the effects of human travel among non homogeneous regions. This mosquito, originating in the tropical and subtropical regions of Southeast Asia, is one of the world's most invasive species, due to two reasons: (i) the global trade in used tyres, which frequently contain small deposits of water where mosquitoes lay eggs, that are therefore transported around the world; (ii) the great adaptability of Aedes albopictus to climate changes, that allows its survival also in temperate zones. Such mosquito is the vector of serious diseases: an outbreak of the tropical disease Chikungunya in Italy in 2007 proved that Europe is definitely at risk for Aedes-borne diseases. Its diffusion can be limited by suitable control policies, whose aim is drastically to reduce the number of larvae and/or adult mosquitos. Therefore, models are useful to study the diffusion of Aedes albopictus, the risk of disease spread in various regions, and the effects of control policies on the development of epidemics.