The effect of mass migration on disease transmission: Evidence from the Venezuelan refugee crisis

Since 2014, millions of Venezuelans have fled to neighboring countries. There is only one accessible land crossing along the Brazil–Venezuela border (Pacaraima) and the Brazilian highway system limits migrants to one route through the Amazon for almost 1000 km. Using this event as a quasi-random treatment, we find that refugee migration increased malaria incidence in Pacaraima, but this was limited to individuals of Venezuelan nationality. We find no effect on Brazilians in Pacaraima or in other municipalities along the main refugee migration route. We therefore reject the hypothesis that Venezuelan refugees increased the risk of malaria among native residents.