I see your point, as well you can't stop living because of bacteria... they are everywhere. Everytime you take a shower you are being showered in PA... it's everywhere. Would I never meet someone with CF? Not true.. I have in the past. Would I meet someone who I knew had B. Capacia? No chance in hell. Problem being is that with something that a bunch of people are showing up to, not everyone knows what they have, and you have no idea what they have. There is an element of mystery to it... too much for me. The only other thing I could see happening which isn't likely is if some bacteria hitched a ride home on a parent to a child with CF.. possible not likely but something to consider.
I worked on cars for years getting tons of cuts and probably a lot of infections from it never stopped me. I'd still do it but I moved to the city and don't have the space anymore. I never let anything stop me from living life, as it sounds like do you.
