Do some research on leprosy. It is nothing like TB or polio, and there is precisely zero chance of a leprosy "epidemic" in the U.S. The handful of cases (currently about a hundred a year) are almost entirely (quite possibly absolutely entirely) in immigrants from countries where it is endemic and their immediate families, and nearly all of them caught it where they came from, after long term close exposure to other infected people -- not here (it takes 4-6 years after infection for symptoms to appear).
I am hardly a liberal when it comes to immigration issues. I think any adult-size person seen crossing our border illegally should be shot on sight, and illegal immigrants who are found already here deported within 24 hours. But if political figures promoting a crackdown on illegal immigration get a reputation as ignorant scaremongers, it will hinder, not help, the cause.
I think you are splitting hairs here and missing the forest....for the trees.