Yes, it is contagious....If you are mugging down with your significant other, you can pass it on for sure.
Same as when you are sexually active with a yeast infection you can pass it on to your partner....men can get yeast infections in their weenis and pass it back to you even after you have cleared yours up with meds.
Just treat it and get rid of it so you don't have to deal with the issues.
Also, if you have a yeast infection in your mouth or vagina, that means you have an overgrowth in your gut.....you really should get on a probiotic to prevent this from happening and keep all those microbes in your tummy in check.
Another way to think of it is....yeast infection is just another thing that your overwhelmed immune system will try to fight. It will keep you immmune response in hyper drive and cause inflammation which you, as a cfer, already have. And, think about it, if your body is unsuccessfully fighting yeast, what it needs to be fighting (pseudo and other cf bugs) are going by the wayside.
Also, many cfers, because they do not treat yeast, begin culturing it in their lungs and once this happens, everytime you are on antibiotics, you have to be on oral antifungals....it can get out of hand really quickly.