So it is bigoted to think that if a country has a high rate of aids, a person from that nation may have it. We have interesting definitions of bigot these days. And it is easy enough to try to brand a person as a bigot if that person voices any concerns about those people.
You didn't speak of a "country" which is simply a political construct, but of "racial groups," a very different thing.
And no, you can't "ASS-U-ME" any such thing. I can see it being a CONCERN, but that's the girl's parents' problem.
I am confident you needn't feel such fear over some "racial group" threatening your precious bodily fluids.