Five or six years ago I was staying in a very nice hotel on Park Avenue. I came back to my room in the middle of the morning to pick up something I had forgotten, and there was an army of uniformed workers with steam machines running around. They had apparently already “done” my room. So I asked one who looked like the foreman (not a hotel employee) what was going on, and he said they were using the steam to eliminate bed bugs in the hotel. As I quietly freaked out, he told me that the guests brought them in in their luggage, mostly, he said, from India and the Middle East, but also the Far East. Turned out he was the owner of this business who making big, big bucks steaming hotels for bedbugs, and was thrilled that use of the chemicals that kill them have been curtailed by the enviros, although the steam isn’t as effective. I did not sleep very well in that hotel, although I didn’t see any bugs, and when I got home I borrowed one of those Shark steam cleaners and blasted my suitcase three times and had all my clothes dry cleaned. Stuff I couldn’t have dry cleaned I just threw away. It was a ghastly experience. So to answer your question, it isn’t just immigration, although that is a part of it.
I used to work in a trucker motel that was a hotbed of prostitution. We used chemicals in the laundry that would eat through your skin.