Jacopo Cerri , Sandro Bertolino

The Asian tiger mosquito (Aedes albopictus) is becoming widespread in Europe, where it can transmit some major arboviruses, including Chikungunya and Dengue. While surveillance initiatives are being implemented and harmonized between states, the spread of A.albopictus is outrunning them and cost-effective surveillance tools are needed.
In this study, we tested whether on-line searches on Google can be adopted to monitor the abundance of A.albopictus. By using data from a long-term monitoring program in the Emilia-Romagna region (Italy), we tested whether the monthly level of infestation was causally related to the monthly GoogleTrends index for the species.
The logarithm of the level of infestation from A.albopictus had a very strong causal effect over the total volume of Google searches about the species. Our statistical model was highly predictive for the GoogleTrends index, suggesting that this cheap on-line metric can be adopted as a proxy for the real level of infestation from A.albopictus.
While GoogleTrends has been adopted to identify and monitor epidemics, including vector-borne diseases, no study tested whether it can reflect the numerical abundance of vector species. To the best of our knowledge, our study, among the few validating GoogleTrends with surveillance data, was the first one opening this possibility. Therefore, we believe that the analysis of on-line search volumes might become an important complement to existing surveillance initiatives for invasive vector species worldwide.