I suspect that most of the very belligerent posters calling for the prosecution of HIV+ people who don't disclose are frightened men who have a lot of sex with strangers without wearing condoms but who don't wish to take responsibility for their own actions and health, therefore are keen to violently blame anyone who might have the virus which they could catch through their own behaviour.

Given that many people who have casual sex don't even ask the name of the other person, it is a bit rich to expect that other person to inform them of their state of health!