President Donald Trump keeps getting kicked around in court when challenges are brought against his ban on travel from seven predominantly Muslim nations. Trump says he wants to halt the flow of people who might be planning attacks. What we cannot forget is that the kind of attack he has in mind is not confined to bombs and shootings. Trump is terrified that immigrants bring diseases with them. If racism fails, public health will likely afford Trump the rationale he seeks for making it difficult for those he does not like to enter our country.