Wow, when you open the can of worms you pick a BIG can, don'tcha!! There were so many lawsuits regarding exposure to HIV that its hard to know where to begin. At the beginning of the HIV "scare," all sorts of questions arose about who, how, where and when one could become infected. Everyone was worried about getting it, treating it or being around it. People wanted to sue because they were possibly exposed to the virus and others because they couldn't get treatment because they had the virus. Now, of course, its a criminal issue as well.
I wasn't trying to open a can. I was just trying to cite an example of suing for probable, future damages (as opposed to actual, current ones). IIRC some of those HIV suits were successful, unless you know an appellate court ruled otherwise. (Obviously, in any such case, the degree of probability would be an issue in trial.)