I have been told that we’re not supposed to talk about Hitler and the Nazis because it evokes unpleasant comparisons to the modern authoritarian movement that’s getting ready to assume power in the United States. Indeed, we’re supposed to try to “make deals” with them so it wouldn’t be prudent to say anything that might make them mad. At least that’s what I hear… Nonetheless, I don’t see how we can talk about this without mentioning the Nazis so I will: President-elect Donald J. Trump is likely to justify his plans to seal off the border with Mexico by citing a public health emergency from immigrants bringing disease into the United States. Now he just has to find one. Mr. Trump last invoked public health restrictions, known as Title 42, in the early days of the pandemic in 2020, when the coronavirus was tearing across the globe. As he prepares to enter office again, Mr. Trump has no such public health disaster to point to. Still, his advisers have spent recent months trying to find the right disease to build their case, according to four people familiar with the discussions. They have looked at tuberculosis and other respiratory diseases as options and have asked allies inside the Border Patrol for examples of illnesses that are being detected among migrants. They also have considered trying to rationalize Title 42 by arguing broadly that migrants at the border come from various countries and may carry unfamiliar disease — an assertion that echoes a racist…