I know that it's changed for emergency workers. If we have an exposure during a call, at least in Texas, we notify the hospital, and they draw blood and do a complete battery of tests. However, universal precautions are a good idea. I quit teaching CPR in the early nineties because I was told that the only thing the American Heart Association would allow us to say was that "no person is known to have contracted AIDS from properly doing CPR. I asked the instructor how many times he'd done CPR on someone with AIDS. He admitted he'd never done CPR for real. I told him I worked in downtown Austin, Texas, in emergency services, and that working on someone with AIDS wasn't hypothetical to me, it was Tuesday. I then mentioned that many people with AIDS weren't simply suffering from AIDS, but had secondary infections, including tuberculosis and hepatitis. Both of these diseases are easily communicable doing proper CPR.
Most people in the later stages of AIDS, at least if they're in bad enough shape to be in a nursing home are pretty identifiable. It's a horrible disease in the later stages. Kaposi's sarcoma causes huge black spots to appear on the body, they waste away to skin and bone, and generally have picked up so many secondary diseases that they sound like the smoking lounge in an emphysema clinic.
Contact tracing is going to be minimally effective on homosexual men, though, because so much of the sex is anonymous. Often, the sex is through gloryholes in porno movie houses, and the men never see anything except what sticks through the wall. Also, according to several surveys of homosexual men done around 12 years ago, over half of the men with AIDS said they would not tell a potential partner they were infected, because they were afraid of "ruining the moment."
Not to wax religious on this, but I think this is the definition of being in bondage to sin, and indicates the grip homosexuality has on men, even though they claim they "love" other men. Over half of the men surveyed were willing to risk condemning a man they claimed to love to a slow, painful, rotting away death for a half hour or so of pleasure.
Kaposi's sarcoma
Some hetero men aren't any better. I know of three women, one caught herpes, one chlamydia, and one venereal warts from men who didn't tell them they had sexually transmitted diseases. Of course, I probably know a lot more women that this has happened to, these are just the ones who confided in me.
In the situations you describe, those are acute situations, which involve emergency workers, and hospitals...and those places are always allowed to know HIV status...but for some reason, nursing homes were not afforded the same information...because nursing homes are not institutions, that take in acute situations....most people in nursing homes, are there to receive help with their daily living activities, or receive custodial care, rather than medical care, tho residents in nursing homes are allowed IVS and meds and such....
So nursing home workers were always put into a different category from EMT workers, and hospital workers...yet nursing home care workers may into contact with the residents bodily fluids(sorry for being graphic), may have to perform CPR on a resident, may accidentally receive an wound from a combative HIV positive resident...
You are right about symptoms of advanced cases of HIV patients being evident...however, I know for sure, that while I was working in the nursing home, I cared for two men who were HIV positive, and neither was in the advanced stages, so it was not evident...I knew, only because my charge nurse, took me aside, looked me in the eye, said, "your patient has a blood borne pathogen, do you understand", and she did not let me go, until she was sure that I understood exactly what she was saying...that my patient was HIV positive...