Doesn't there being exposed create a likeleyhood that was not there had they not been exposed?
Being exposed to someone with a disease does not mean that "there is a likelihood that it has already spread from him to others in the frum community."
Merely being in the same room with someone is not enough to catch this.
Even shaking his hand would not be enough if he did not have secretions on his hand and the person who shook his hand did not go to his own mouth or nose with his hand afterwards.
Although it is possible that someone could have caught it, I think that its a leap to say that "there is a likelihood that it has already spread from him to others in the frum community."