Research suggests there are social perceptions of threat toward refugees... Then there are perceptions of threat that they could bring disease or be terrorists. Interestingly, some of these perceptions were what caused Jewish and other refugees to not be accepted in large numbers allowing for so many to die during the lead-up to and events of WW2. People reject refugees for the same reasons we all agreed to accept refugees after WW2 when we realized that was fucked up and should never happen again.