Everything from tape worms to TB is coming across the border. Their hosts end up working in restaurants and food related businesses, e.g., chicken processing plants, 7/11 stores. Better boil your Slurpees for 15 minutes before you eat them.
You are absolutely right!
It makes me angry to think how they get away with this, and our ancestors who had to come in through Ellis Island were put through a rigorous and often embarrassing health exam. They would not be admitted if they had pink eye!
I had a childhood friend who, in hr twenties, went to Italy to visit her father's family. While there, she fell in love with a wonderful young man. Her father, a cabinet-maker, approved of the young man, and had a job for him and a house all set up for the young couple. He was turned back by US Immigration 3 times in 10 years for having TB antibodies in his blood, although he was perfectly healthy. This girl was heartbroken and never married.
Today, he could just hop on a plane and come in through Kennedy Airport, or fly to Mexico and drive across the border.