I have just altered my travel plans for 2017 to include Berlin where I am going to search out and hug every obvious immigrant I can find. I don't pray, but my fervent hopes and wishes will be with Ms. Merkel and like minded people. 
I would not call Trump LePen Wilders Farrage et al a "disease"  but they are surely a symptom of how fear of a few, a very few, mentally ill people can be used to turn us against our fellow human beings based on nothing more than the accident of their birthplace. I woud simply ask those condemming "Muslim immigrants" to remember the Oklahoma City Bomber, the Montreal massacre shooter, and take your pick of the most recent  hundred or so mass murderers in North America. What percentage were "Muslim"  vs "Christian" vs "aetheist" or  "native born" vs "immigrant"?  
Unbiased reflection shows it is not "immigrants" or any labelled group that is the problem. It is our tendency to label and scapegoat others that is the root of  this current "disease"..