Depends on the sort of prostitution, the high end 'escort' girl doesn't need protection, chances are she made her own choice to sell sex, whatever, I don't care about the morals of the issue.
The problem I have, working as a police officer in an inner city area with its own red light district is with what the law calls common prostitution. Girls walking the streets soliciting. Every one of the girls that gets locked up, charged and put in to drug intervention programs is a hopeless drug addict. They're the walking dead, skin and bones, stink, look about ten years older than they are and you can see the scars and bruises from the rapes and beatings. Do they care about how degraded or vulnerable they are? They couldn't give a fuck, all they care about is getting the next crack hit (the crack heads are even more messed up then the smack heads, but they normally take both drugs).
Even the briefest conversation with these girls shows that they're not dumb either, they acknowledge how messed up their lives are they're just beyond caring. That's a level of addiction that I find hard to comprehend.
The saddest thing is to look back through their custody pictures and see pictures of them as normal teenagers having been arrested for shop lifting or drunk and disorderly and watch the decline as they slip into drug addiction.
Most of the stories I've heard start with girls drinking, then smoking weed, getting into speed and pills, then a bit of coke, then it's the big jump to crack or heroin. They get into prostitution gradually, giving a dealer a blow job for a rock, maybe fucking one of his mates because they can't afford what they need. Once the addictions full blown it's not such a big departure to start walking the streets, just working for drugs, £10 for a hand job, £20 for a blow job, both go straight to the dealer, get high then get straight back out on the streets again. Apart from the rapes and arrests that's how it goes until they either overdose or disappear.
It's just horrible, prostitution may be a crime but the girls are the victims, problem is they're beyond caring. Conversely, the male smack heads normally turn to shop lifting or burglary, I've never dealt with a male prostitute.
As for STI the girls say they only really do hand/blow jobs and rarely have full sex and they always use condoms. However, I know that there are girls out there with HIV that are still working. The punters who we lock up with these girls tend to be middle-aged, married and (in Birmingham at least) Asian. I've no idea why they pay to go with these girls as they're like the walking dead, I think they must get off on the exploitive, nastiness of it. If these scum bags didn't get off on exploiting a drug addicts misery then they wouldn't be out selling sex, however, no matter how ravaged, dirty, stinking and miserable the girl is there's always some lowlife who'll pay her for sex.
That's the problem, men getting off on exploiting fucked up vulnerable women. I don't know how that can be changed and that's depressing.