Digby posted this very alarming reminder of the history of immigration at the US-Mexican border.
Upon entering the USA, Mexican laborers were once routinely deloused with DDT and Zyklon-B (yes, that's right, the powerful German insecticide good for killing lice and humans), required to be strip-searched (men and women), and given gasoline baths.
I've always been puzzled by the American obsession with cleanliness, and by the widely held conviction that everyone beyond our borders is dirty. We are a very dirty people ourselves.
She concludes her post with this insight:
Humans often tend to kick those members of society who are of a lower ethnic or racial caste or are on a lower socio-economic scale because they feel impotent to do anything to those who are the real cause of their angst and insecurity. (And it's a special feature of right wing populism.) Our unique American spin on this is that the immigrant melting pot has also made this particular impulse a rite-of-passage for more established immigrants to prove their American bona fides. (And we always have blacks to throw to the jackals if the rubes get really restless.)