A personal overview of epidemic models for mosquito-borne infections

In this paper, we present a brief, nonexhaustive overview of the features we consider most relevant in models for mosquito-transmitted infections, comparing them with the corresponding features in models for directly-transmitted infections. In particular, we focus on the basic reproduction number R0 and its relations with the exponential growth rate, the probability of an outbreak, and the final size of the epidemic. The concept of a threshold for epidemic spread based on the basic reproduction number (R0 > 1) was first introduced by Ronald Ross for malaria. Later, the study of models for vector-transmitted infections, where the vector naturally follows a seasonal cycle, has led to a definition of R0 when model parameters are time-periodic. Host heterogeneity in attractiveness to mosquitoes leads to the counter-intuitive result that protective behaviors may increase R0; we present the assumptions behind this result, and the factors that can instead help decreasing R0.