Changing risk of arboviral emergence in Catalonia due to higher probability of autochthonous outbreaks

Background: The lack of previous exposure to arbovirus and the ongoing geographical expansion of viable vector populations has fostered the implementation of preventive strategies in those areas more prone to disease importation. Catalonia receives a wealth of travelers from Southeast Asia, South America and the Caribbean and around 700 cases of imported arbovirosis (2012-2016, totaling dengue, chikungunya, and Zika), have been notified in primary care health centers, traveler advice public health services and main hospitals. With the large asymptomatic proportion of infections well-known for these diseases, the threat for autochthonous outbreaks increases in those areas that, for particular environmental and socio-demographic conditions, might be more susceptible. Operational early-warning systems are lacking in most places where these outbreaks pose a serious health treat.Methods: Here we present the ARBOCAT platform for the prediction of autochthonous outbreaks of ar-boviruses emanating from imported cases, implemented for Catalonia at municipality resolution. Three sub-models provide estimations for importation rates and the basic reproduction number and their outcomes are used to fit a stochastic compartmental model that yields the generation time and the risk of local outbreaks for 948 municipalities. We used also ISIMIP-2b (The Inter-Sectoral Impact Model Intercomparison Project) temperature data to generate future outbreak risk maps for the RCP 2.6 and RCP 8.5 scenarios (where RCP is Representative Concentration Trajectories).Findings: Substantial differences exist between the low and middle-risk scenarios but most Catalonia munici-palities are not at risk for a sustained epidemic. Instead, high R0 are obtained for the maximum risk scenario, with the number of municipalities affected being over 150. In the RCP 8.5 scenario, many of the highest risk areas lie in the most populated cities in the coastal region, particularly in the south near to the Ebre's river.Interpretation: The current outbreak risk is low, both for the mean and minimum temperature scenarios and rises in the high-risk situation. Projections for 2050 are not so optimistic, leading to a significant increase in affected municipalities, over 100, mainly in the coastal area due to the temperature increase followed in RCP 8.5.