Vector-borne infections: risk based and cost effective surveillance systems

Recent outbreaks of vector-borne diseases (VBD) highlight the need for effective surveillance systems for (early) detection of VBDs. Active surveillance, i.e. searching for infected individuals, is expensive for emerging vector-borne diseases, because of required repeated sampling. Furthermore, the introduction of an emerging disease will occur focal and at low initial prevalence. Focusing active surveillance using risk factors of disease may increase the sensitivity and improve the cost-effectiveness of the system. We propose a dynamic system for risk-based surveillance of VBD based on these three pillars: 1) estimating risk of introduction, 2) risk of spread (modeling R0) and 3) analysing routinely collected production and health related data. Together these three constitute an effective tool for targeted surveillance on time windows and areas. Each of the three components provides independent indices for the risk of outbreaks, and together provide a more accurate risk score, taking into account the potential for occurrence (risk of transmission and of introduction) and the probability that an outbreak is going on (syndrome and passive surveillance). This approach may greatly focus the costly active surveillance increasing the output of the surveillance effort. Here we will present the first preliminary results of our efforts to combine risk of introduction, R0 modelling and signals from production and health related data. We will show the methodology to combine these three different sources of information.